A, ~ -~ ~EERMISTD-984 40 7 3 LL

EAE-A/STD- q IY V

COMMENTS ON DOE'S PROPOSED

MINIMUM EFFICIENCY STANDARDS

FOR

RESIDENTIAL CENTRAL AIR

CONDITIONERS AND HEAT PUMPS

November 16, 2000

Comments by John Proctor. P.E..

President Proctor Engineering Group, Ltd. San Rafael, California

Cited by Pacific Gas and Electric Company in their submission on

February 4, 2000.

9 13doe.doc Page 1

EE-RM-STD-98-440 COMMENT 73LL

· ~ 

EE_RM/STD-98-440 :#-13lL 

E. E -IU'II.jSTD - q 1-Y If 0 

COMMENTS ON DOE'S PROPOSED 

MINIMUM EFFICIENCY STANDARDS 

FOR 

RESIDENTIAL CENTRAL AIR 

CONDITIONERS AND HEAT PUMPS 

November 16, 2000 

Comments by John Proctor. P.E.. 

President Proctor Engineering Group. Ltd. San Rafael, California 

Cited by Pacific Gas and Electric Company in their submission on 

FebnJary 4.2000. '" 

9113doe.doc Page 1 

· ~ 

EE_RM/STD-98-440 :#-13lL 

E. E -IU'II.jSTD - q 1-Y If 0 

COMMENTS ON DOE'S PROPOSED 

MINIMUM EFFICIENCY STANDARDS 

FOR 

RESIDENTIAL CENTRAL AIR 

CONDITIONERS AND HEAT PUMPS 

November 16, 2000 

Comments by John Proctor. P.E.. 

President Proctor Engineering Group. Ltd. San Rafael, California 

Cited by Pacific Gas and Electric Company in their submission on 

FebnJary 4.2000. '" 

9113doe.doc Page 1 
EE-RM/STD-98-440 1

To state the obvious,

TXVs improve SEER.

If that alone were their effect, they should be an

option that could be traded off against other methods

of obtaining a specified performance.

But TXVs do far more than that

TXVs or their equivalent

should be required

because they provide substantial in field

benefits that are not reflected in SEER.

The primary advantages of the TXV are that they

perform better than the short tube orifice when the

airflow across the inside coil is low and when the

amount of refrigerant in the unit is different from that

specified by the manufacturer.

911 3doe.doc Page 2

EE-RM-STD-98-440 COMMENT 73LL

EE-RM/STD-98-440-Jf 'l?J..- LlTo state the obvious, 

TXV s improve SEER. 

If that alone were their effect, they should be an 

option that could be traded off against other methods 

of obtaining a specified performance. 

But TXV s do far more than that 

TXV s or their equivalent 

should be required 

because they provide substantial in field 

benefits that are not reflected in SEER. 

The primary advantages of the TXV are that they 

perform better than the short tube orifice when the 

airflow across the inside coil is low and when the 

anlount of refrigerant in the unit is different from that 

specified by the manufacturer. 

q I I )doe .doc Page 2 

EE-RM/STD-98-440-Jf 'l?J..- LlTo state the obvious, 

TXV s improve SEER. 

If that alone were their effect, they should be an 

option that could be traded off against other methods 

of obtaining a specified performance. 

But TXV s do far more than that 

TXV s or their equivalent 

should be required 

because they provide substantial in field 

benefits that are not reflected in SEER. 

The primary advantages of the TXV are that they 

perform better than the short tube orifice when the 

airflow across the inside coil is low and when the 

anlount of refrigerant in the unit is different from that 

specified by the manufacturer. 

q I I )doe .doc Page 2 
EE-RMISTD-98-440-- 13. L

New Field Data

New field data confirms widespread mischarge

and low airflow.

There is new, clear, and overwhelming evidence from

more than 4000 units tested in California in this year

that 62% are mischarged by more than 5%.

This evidence further quantifies the distribution of

the mischarge.

9113doe.doc Page 3

EE-RM-STD-98-440 COMMENT 73LL < .• 

EE-RM/STD-98-44(}"'1Y'J~- L-LNew Field Data 

New field data confirms widespread mischarge 

and low airflow. 

There is new, clear, and overwhelming evidence from 

more than 4000 units tested in California in this year 

that 62% are mischarged by more than 5%. 

This evidence further quantifies the distribution of 

the mischarge. 

91 Udoe.doc Page :< 

< .• 

EE-RM/STD-98-44(}"'1Y'J~- L-LNew Field Data 

New field data confirms widespread mischarge 

and low airflow. 

There is new, clear, and overwhelming evidence from 

more than 4000 units tested in California in this year 

that 62% are mischarged by more than 5%. 

This evidence further quantifies the distribution of 

the mischarge. 

91 Udoe.doc Page :< 
62% of Population Mischarged 40% -

5_-- Correct Charge 35% . -- ____ ___________

*. 30% 35% _ _ _ _ _ _ __ _ _

a 25% _-___ _

a.,

20%

o 15%

Q) 1Undercharge Overcharge m

5% -------- -_-__. ---- g

0.2 0.3 0.5 0.7 0.9 1.1 1.3 1.5 1.8

Refrigerant Charge

(fraction of correct charge) v charge) -..

EE-RM-STD-98-440 COMMENT 73LL

c: 

o 

...... 

(1l 

::J 

a. 

o 

a. 

(1l 

...... 

o 

t-

'too 

...... 

c: 

Q) 

o 

r... 

Q) 

a. 

25% 

20% 

15% 

10% 

5% -

0% -

62% of Population Mischarged 

- Correct Charge ------- ------ --- ------- ------------------

- - ------- - -- ------------------------ --------~ ---------

Undercharge Overcharge 

0.2 0.3 0.5 0.7 0.9 1.1 1.3 

Refrigerant Charge 

(fraction of correct charge) 

1.5 1.8 

\ 

\' 

c: 

o 

...... 

(1l 

::J 

a. 

o 

a. 

(1l 

...... 

o 

t-

'too 

...... 

c: 

Q) 

o 

r... 

Q) 

a. 

62% of Population Mischarged 

- Correct Charge ._------------

30% -. ---~ --- ----------------~---- ------.-~ -_ .. _---

25% 

20% 

15% 

10% 

5% -

0% -

0.2 

Undercharge Overcharge 

0.3 0.5 0.7 0.9 1.1 1.3 1.5 1.8 

Refrigerant Charge 

(fraction of correct charge) 
$ 1

co 009

g ° 90.9

ue 0 0.8

E E 0.7

u E

u o 0.6

0.5 TXV

'" / Short Tube Orifice E uw 0.4

z 14

0

. 0.3

0.2

0.1

0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4

Refrigerant Charge (fraction of manufacturer's recommendation)

EE-RM-STD-98-440 COMMENT 73LL

\ 

~ '~ 

d 

~ 

~ • co 

m , 

~ 

~ a: , 

w 

w 

1.1 

1 

-

~ 0.9 L.. 

n:J 

.c 

u 0.8 

"t:J »Q) 

u"t:J 

t: t: 0.7 

Q) Q) 

'0 E H: E 

w 8 0.6 

"t:J Q) Q) L.. 

~ rt; 0.5 

effi o W 0.4 

Z'O 

c: 

o 0.3 ~ 

o 

n:J 

.:: 

- 02 . 

0.1 

o 

)K-i-XVU --- U --- - ----mu,l 

• Short Tube Orifice -~--------------------~------- ---.~--

0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 

Refrigerant Charge (fraction of manufacturer's recommendation) 

\ 

~ '~ 

d 

~ 

~ • co 

m , 

~ 

~ a: , 

w 

w 

1.1 

1 

-

~ 0.9 L.. 

n:J 

.c 

u 0.8 

"t:J »Q) 

u"t:J 

t: t: 0.7 

Q) Q) 

'0 E H: E 

w 8 0.6 

"t:J Q) Q) L.. 

~ rt; 0.5 

effi o W 0.4 

Z'O 

c: 

o 0.3 ~ 

o 

n:J 

.:: 

- 02 . 

0.1 

o 

0.5 

~------.~--- -------------,------------------. 

0.6 0.7 0.8 0.9 1.0 

)K-i-xv---- U ---- -----,1 

• Short Tube Orifice -~--------------------~------- ---.~--

1.1 1.2 

Refrigerant Charge (fraction of manufacturer's recommendation) 

1.3 1.4 
0.98

oda 0.96

I-

. , 0.92

>. ,, 0.88 9

" E

.a t 0.88

w I 0.86

N| (0.84

Er 0.8

z 0

z C 0.8

0¢ -""- TXV

u 0.78 _ 7--Short Tube Orifice

0.76

0.74

0.72

0.7 - ---

0.5 0.55 0.6 0.65 0.7 0.75 0.8 0.85 0.9 0.95

Air Flow (fraction of 400 cfm per ton)

EE-RM-STD-98-440 COMMENT 73LL

j 

\ 

~ 

t:-

~ \ 

o 

l 

~ 

Q 

t; 

:i -

a: 

w • 

w 

-

0_98 

0.96 

0.94 

g 0.92 +oJ 

L. 

>- ~ 0.9 

g E .~ 't; 0.88 

.~ 0 ffi ~ 0.86 

-0 +oJ 

~ ~ 0.84 

=w raw E .... 0.82 

o 0 

z c 0.8 o 

~ ra 0.78 . .:: 

- 0.76 -

0.74 

0.72 

------.. -----.. ---------------------------------- -----------.--.. ---._---_---_----.----.----:~;;;-;;;;;;;;;;;;;;;;-=ii)Klll-~==-' 

=-;t(- -----~ 

-.----~-----

M( TXV 

• Short Tube Orifice 

0.7 .~----_4------_+------_r------~------+_----~~----~------_+------~----~ 

0.5 0.55 0.6 0.65 0.7 0.75 0.8 0.85 0.9 0.95 1 

Air Flow (fraction of 400 cfm per ton) 

j 

\ 

~ 

t:-

~ \ 

o 

l 

~ 

Q 

t; 

:i -

a: 

w • 

w 

-

0_98 

0.96 

0.94 

g 0.92 +oJ 

L. 

>- ~ 0.9 

g E .~ 't; 0.88 

.~ 0 ffi ~ 0.86 

-0 +oJ 

~ ~ 0.84 

=w raw E .... 0.82 

o 0 

z c 0.8 o 

~ ra 0.78 . .:: 

- 0.76 -

0.74 

0.72 

------.. -----.. ---------------------------------- -----------.--.. ---._---_---_----.----.----:~;;;-;;;;;;;;;;;;;;;;-=ii)Klll-~==-' 

=-;t(- -----~ 

-.----~-----

M( TXV 

• Short Tube Orifice 

0.7 .~----_4------_+------_r------~------+_----~~----~------_+------~----~ 

0.5 0.55 0.6 0.65 0.7 0.75 0.8 0.85 0.9 0.95 1 

Air Flow (fraction of 400 cfm per ton) 
EE-R M/STD-98-440" / 7/--L

Analysis

When the field data is combined with the difference

in performance between TXVs and short tube orifices

the overall effect of requiring TXVs is shown.

There are numerous national studies that repeatedly

show that over half the units in the field are running

at low airflow.

9113doe.doc Page 4

EE-RM-STD-98-440 COMMENT 73LL · . EE-RM/STD-98-440if-13.-~. 

Analysis 

When the field data is combined with the difference 

in performance between TXV s and short tube orifices 

the overall effect of requiring TXV s is shown. 

There are numerous national studies that repeatedly 

show that over half the units in the field are running 

at low airflow. 

9113doe.doc Page ..) 

· . EE-RM/STD-98-440if-13.-~. 

Analysis 

When the field data is combined with the difference 

in performance between TXV s and short tube orifices 

the overall effect of requiring TXV s is shown. 

There are numerous national studies that repeatedly 

show that over half the units in the field are running 

at low airflow. 

9113doe.doc Page ..) 
EE-RM/STD-98-440 --r 73/

Result

All this evidence combined shows an average field

savings of 11% when TXVs are used on all units

This is equivalent to the difference between SEER 12

and SEER 13.5.

9113doe.doc Page 5

EE-RM-STD-98-440 COMMENT 73LL

EE-RM/STD-98-440·· 11 16-[L 

Result 

All this evidence combined shows an average field 

savings of 11 % when TXV s are used on all units 

This is equivalent to the difference between SEER 12 

and SEER 13.5. 

q 1 13doe .doc Page 5 

EE-RM/STD-98-440·· 11 16-[L 

Result 

All this evidence combined shows an average field 

savings of 11 % when TXV s are used on all units 

This is equivalent to the difference between SEER 12 

and SEER 13.5. 

q 1 13doe .doc Page 5 
EE-RM/STD.98-440 - /_ - C

Equivalency

Any device that ensures performance in the field by

tolerating incorrect charge and low airflow will

achieve the necessary effect. A simple performance

criteria can be written that allows devices other than

TXVs to prove that they have equivalent or better

tolerance to incorrect charge and low airflow.

91 13doe.doc Page 6

EE-RM-STD-98-440 COMMENT 73LL

EE-RM/STD-98-440 -1/ 13 _ L, Lr 

Equivalency 

Any device that ensures performance in the field by 

tolerating incorrect charge and low airflow will 

achieve the necessary effect. A simple performance 

criteria can be written that allows devices other than 

TXV s to prove that they have equivalent or better 

tolerance to incorrect charge and low airflow. 

9113doe.doc Page 6 

EE-RM/STD-98-440 -1/ 13 _ L, Lr 

Equivalency 

Any device that ensures performance in the field by 

tolerating incorrect charge and low airflow will 

achieve the necessary effect. A simple performance 

criteria can be written that allows devices other than 

TXV s to prove that they have equivalent or better 

tolerance to incorrect charge and low airflow. 

<) 113doe.doc Page 6 
EE-RM/STDg98-4 40 - 7-

Potential Specification

The performance specification could be along these

lines:

Each unit must have a device or combination of

devices that produces

1) an EER95 at 90% and 120% of full charge

with no more than a 4% difference from EER95

at full charge and

2) EER95 at 80% of full (certification test) air

flow within 2% of EER95 at certification test

airflow.

If the unit has a TXV, the performance is

assumed to meet these specifications.

911 3doe.doc Page 7

EE-RM-STD-98-440 COMMENT 73LL

· . 

EE-RM/STO .. 98-440-1f·7s./ L/"---

Potential Specification 

The performance specification could be along these 

lines: 

Each unit must have a device or combination of 

devices that produces 

1) an EER95 at 90% and 120% of full charge 

with no more than a 4% difference from EER95 

at full charge and 

2) EER95 at 800/0 of full ( certification test) air 

flow within 2% of EER95 at certification test 

airflow. 

If the unit has a TXV, the performance is 

assumed to meet these specifications. 

91 13doe .doc Page 7 

· . 

EE-RM/STO .. 98-440-1f·7s./ L/"---

Potential Specification 

The performance specification could be along these 

lines: 

Each unit must have a device or combination of 

devices that produces 

1) an EER95 at 90% and 120% of full charge 

with no more than a 4% difference from EER95 

at full charge and 

2) EER95 at 800/0 of full ( certification test) air 

flow within 2% of EER95 at certification test 

airflow. 

If the unit has a TXV, the performance is 

assumed to meet these specifications. 

91 13doe .doc Page 7 
EE-RM/STD-98-440 -'73--

Reliability of TXVs

We know of no evidence that TXVs are less reliable

or subject to tampering any more than other

components of the air conditioner.

TXVs are regularly used in higher efficiency units

and commercial rooftop units.

They are installed and the units serviced daily all

across the United States. The installation and service

technicians in the field today are familiar with and

work on both types of units.

It is certainly feasible for manufacturers to produce

TXVs that are not adjustable.

91 13doe.doc Page 8

EE-RM-STD-98-440 COMMENT 73LL

EE-RM/STD-98-440 "'#73 -- L L 

Reliability of TXV s 

We know of no evidence that TXV s are less reliable 

or subj ect to tampering any more than other 

components of the air conditioner. 

TXV s are regularly used in higher efficiency units 

and commercial rooftop units. 

They are installed and the units serviced daily all 

across the United States. The installation and service 

technicians in the field todav are familiar with and .; 

work on both types of units. 

It is certainly feasible for nlanufacturers to produce 

TXVs that are not adjustable. 

C) 11 ~doe.doc Page 8 

EE-RM/STD-98-440 "'#73 -- L L 

Reliability of TXV s 

We know of no evidence that TXV s are less reliable 

or subj ect to tampering any more than other 

components of the air conditioner. 

TXV s are regularly used in higher efficiency units 

and commercial rooftop units. 

They are installed and the units serviced daily all 

across the United States. The installation and service 

technicians in the field todav are familiar with and .; 

work on both types of units. 

It is certainly feasible for nlanufacturers to produce 

TXVs that are not adjustable. 

C) 11 ~doe.doc Page 8 
EE-RM/STD-98-440-t .,5 -L

Reliability of Current Ratings

The current SEER ratings are unreliable as estimators

of field performance.

When these units operate their true efficiency usually

does not meet the advertised efficiency.

This situation is made much better when TXVs are

used across the board.

For $8 to $11 you have bought an insurance policy

on the efficiency of your unit.

91 1 doe.doc Page 9

EE-RM-STD-98-440 COMMENT 73LL · . EE.RM/STO.98.440 ... :tF~ 13-~ 

Reliability of Current Ratings 

The current SEER ratings are unreliable as estimators 

of field performance. 

When these units operate their true efficiency usually 

does not meet the advertised efficiency. 

This situation is made much better when TXV s are 

used across the board. 

For $8 to $11 you have bought an insurance policy 

on the efficiency of your unit. 

l) 11 :<doc.doc Page 9 

· . EE.RM/STO.98.440 ... :tF~ 13-~ 

Reliability of Current Ratings 

The current SEER ratings are unreliable as estimators 

of field performance. 

When these units operate their true efficiency usually 

does not meet the advertised efficiency. 

This situation is made much better when TXV s are 

used across the board. 

For $8 to $11 you have bought an insurance policy 

on the efficiency of your unit. 

l) 11 :<doc.doc Page 9 
EE-RM/STD-98-440-- 713-

Reliability of TXVs II

On July 24, 2000 Trane Company supported the

mandatory use of thermal expansion valves on all

new central air conditioners and heat pumps.

91 13doe.doc Page 10

EE-RM-STD-98-440 COMMENT 73LL

EE.RM/STD.98-440 .... 1F 13.--L I---

Reliability of TXV s II 

On July 24, 2000 Trane Company supported the 

mandatory use of thermal expansion valves on all 

new central air conditioners and heat pumps. 

911~doe.doc Page 10 

EE.RM/STD.98-440 .... 1F 13.--L I---

Reliability of TXV s II 

On July 24, 2000 Trane Company supported the 

mandatory use of thermal expansion valves on all 

new central air conditioners and heat pumps. 

911~doe.doc Page 10 
EE-RM/STD-98-440/ ?5- 7 LOptions in Achieving Higher Efficiencies

There are numerous ways to obtain higher SEERs

and/or EERs in air conditioners and heat pumps.

These include:

* Increased coil face area

* Increased tube rows

* Increased fin density

® Improved inside fan/motor efficiency (e.g. ECM

motors)

* Improved heat exchanger efficiency (e.g. rifling)

e TXVs

* Compressor efficiency

* Relative compressor size (multi speed or

multiple compressor)

91 I3doe.doc Page 1

EE-RM-STD-98-440 COMMENT 73LL

EE-RM/STD-98-440-<tt 7.?·- LL/ 

Options in Achieving Higher Efficiencies 

There are numerous ways to obtain higher SEERs 

and/or EERs in air conditioners and heat pumps. 

These include: 

., Increased coil face area 

• Increased tube rows 

., Increased fin density 

• Improved inside fan/motor efficiency (e.g. ECM 

motors) 

., Improved heat exchanger efficiency (e.g. rifling) 

"* TXVs 

• Compressor efficiency 

• Relative compressor size (multi speed or 

multiple compressor) 

() 113doe .doc Page 11 

EE-RM/STD-98-440-<tt 7.?·- LL/ 

Options in Achieving Higher Efficiencies 

There are numerous ways to obtain higher SEERs 

and/or EERs in air conditioners and heat pumps. 

These include: 

., Increased coil face area 

• Increased tube rows 

., Increased fin density 

• Improved inside fan/motor efficiency (e.g. ECM 

motors) 

., Improved heat exchanger efficiency (e.g. rifling) 

"* TXVs 

• Compressor efficiency 

• Relative compressor size (multi speed or 

multiple compressor) 

() 113doe .doc Page 11 
EE-RM/STD-98-440 ' 93 L L

DRAFT

OVERVIEW

Description of Technology

A thermostatic expansion valve (TXV) is a refrigerant-metering device used in residential and

commercial air conditioners. The TXV is one of two common metering devices, the other being a

short tube orifice. Compared to the short tube orifice, TXVs are more costly and more effective in

controlling refrigerant flow under varying conditions.

Function of a Metering Device

The area of the inside coil (evaporator) used in phase change from liquid refrigerant to vapor

substantially effects the capacity and efficiency of an air conditioner. The larger portion of the coil

used for phase change, generally the higher the capacity.

The refrigerant-metering device controls the amount of refrigerant liquid flowing into the inside

coil and thus the phase change area. If too much liquid flows into the inside coil not all the

refrigerant changes phase in the coil and some liquid may reach the compressor. This can

damage the compressor. If too little refrigerant flows into the coil the phase change area of the

coil is less than ideal and the refrigerant vapor returning to the compressor is superheated. Some

superheat is considered desirable because it protects the compressor from liquid refrigerant. Too

much superheat however represents wasted evaporator coil area and the superheat energy must

be rejected later in the cycle at the outside coil. The durability of the compressor can be

compromised by too much superheat as well. The compressor is cooled by the refrigerant vapor

returning from the inside coil. High superheat provides less cooling to the compressor.

The idealized system provides exactly 0 degrees of superheat and no liquid to the compressor.

Such a system would protect the compressor without wasting coil area on producing superheat.

The refrigerant metering device must work under a variety of conditions: inside temperature and

humidity, outside temperature, as well as "off-design" operation (incorrect airflow across the

inside coil and incorrect amount of refrigerant in the air conditioner).

Metering Device Description

The short tube orifice is the least costly metering device and the most common. The short tube

orifice has a small hole, which meters the flow of refrigerant based only on the pressure

difference across the hole.

Thermostatic expansion valves are more complex. They consist of a temperature sensor, pressure

diaphragm, and a variable orifice. The TXV dynamically responds to more than the pressure

difference. The TXV is a "constant superheat valve". It meters refrigerant flow to maintain a

nearly constant temperature difference between the saturated refrigerant in the evaporator coil

and the refrigerant leaving the evaporator coil. TXVs are generally set to provide between 10 °F

and 15 °F of superheat.

PG&E TXV Impact Review DRAFT Oct. 23, 2000 Page 1-1 Proctor Engineering Group, Ltd.

EE-RM-STD-98-440 COMMENT 73LL

EE-RM/STD-98-440 "* 7E> L L 

DRAFT 

OVERVIEW 

Description of Technology 

A thermostatic expansion valve (TXV) is a refrigerant-metering device used in residential and 

commercial air conditioners. The TXV is one of two common metering devices, the other being a 

short tube orifice. Compared to the short tube orifice, TXVs are more costly and more effective in 

controlling refrigerant flow under varying conditions. 

Function of a Metering Device 

The area of the inside coil (evaporator) used in phase change from liquid refrigerant to vapor 

substantially effects the capacity and efficiency of an air conditioner. The larger portion of the coil 

used for phase change, generally the higher the capacity. 

The refrigerant-metering device controls the amount of refrigerant liquid flowing into the inside 

coil and thus the phase change area. If too much liquid flows into the inside coil not all the 

refrigerant changes phase in the coil and some liquid may reach the compressor. This can 

damage the compressor. If too little refrigerant flows into the coil the phase change area of the 

coil is less than ideal and the refrigerant vapor returning to the compressor is superheated. Some 

superheat is considered desirable because it protects the compressor from liquid refrigerant. Too 

much superheat however represents wasted evaporator coil area and the superheat energy must 

be rejected later in the cycle at the outside coil. The durability of the compressor can be 

compromised by too much superheat as well. The compressor is cooled by the refrigerant vapor 

returning from the inside coil. High superheat provides less cooling to the compressor. 

The idealized system provides exactly 0 degrees of superheat and no liquid to the compressor. 

Such a system would protect the compressor without wasting coil area on producing superheat. 

The refrigerant metering device must work under a variety of conditions: inside temperature and 

humidity, outside temperature, as well as "off-design" operation (incorrect airflow across the 

inside coil and incorrect amount of refrigerant in the air conditioner). 

Metering Device Description 

The short tube orifice is the least costly metering device and the most common. The short tube 

orifice has a small hole, which meters the flow of refrigerant based only on the pressure 

difference across the hole. 

Thermostatic expansion valves are more complex. They consist of a temperature sensor, pressure 

diaphragm, and a variable orifice. The TXV dynamically responds to more than the pressure 

difference. The TXV is a "constant superheat valve". It meters refrigerant flow to maintain a 

nearly constant temperature difference between the saturated refrigerant in the evaporator coil 

and the refrigerant leaving the evaporator coil. TXVs are generally set to provide between 10 OF 

and 15 OF of superheat. 

PG&E TXV Impact Review DRAFT Oct. 23,2000 Page 1-1 Proctor Engineering Group, Ltd. 

EE-RM/STD-98-440 "* 7E> L L 

DRAFT 

OVERVIEW 

Description of Technology 

A thermostatic expansion valve (TXV) is a refrigerant-metering device used in residential and 

commercial air conditioners. The TXV is one of two common metering devices, the other being a 

short tube orifice. Compared to the short tube orifice, TXVs are more costly and more effective in 

controlling refrigerant flow under varying conditions. 

Function of a Metering Device 

The area of the inside coil (evaporator) used in phase change from liquid refrigerant to vapor 

substantially effects the capacity and efficiency of an air conditioner. The larger portion of the coil 

used for phase change, generally the higher the capacity. 

The refrigerant-metering device controls the amount of refrigerant liquid flowing into the inside 

coil and thus the phase change area. If too much liquid flows into the inside coil not all the 

refrigerant changes phase in the coil and some liquid may reach the compressor. This can 

damage the compressor. If too little refrigerant flows into the coil the phase change area of the 

coil is less than ideal and the refrigerant vapor returning to the compressor is superheated. Some 

superheat is considered desirable because it protects the compressor from liquid refrigerant. Too 

much superheat however represents wasted evaporator coil area and the superheat energy must 

be rejected later in the cycle at the outside coil. The durability of the compressor can be 

compromised by too much superheat as well. The compressor is cooled by the refrigerant vapor 

returning from the inside coil. High superheat provides less cooling to the compressor. 

The idealized system provides exactly 0 degrees of superheat and no liquid to the compressor. 

Such a system would protect the compressor without wasting coil area on producing superheat. 

The refrigerant metering device must work under a variety of conditions: inside temperature and 

humidity, outside temperature, as well as "off-design" operation (incorrect airflow across the 

inside coil and incorrect amount of refrigerant in the air conditioner). 

Metering Device Description 

The short tube orifice is the least costly metering device and the most common. The short tube 

orifice has a small hole, which meters the flow of refrigerant based only on the pressure 

difference across the hole. 

Thermostatic expansion valves are more complex. They consist of a temperature sensor, pressure 

diaphragm, and a variable orifice. The TXV dynamically responds to more than the pressure 

difference. The TXV is a "constant superheat valve". It meters refrigerant flow to maintain a 

nearly constant temperature difference between the saturated refrigerant in the evaporator coil 

and the refrigerant leaving the evaporator coil. TXVs are generally set to provide between 10 OF 

and 15 OF of superheat. 

PG&E TXV Impact Review DRAFT Oct. 23,2000 Page 1-1 Proctor Engineering Group, Ltd. 
EE-RMISTD-98-440 /'73 -

Overview

A short tube orifice provides a varying amount of superheat from 0 °F to over 30 °F.

Performance Influences of the Metering Device

The performance of the air conditioner is influenced by the interaction of the metering device

with the following parameters:

* Differing outdoor temperatures

· Differing indoor conditions of humidity and temperature

* Differing air flows across the inside coil

* Differing amounts of refrigerant in the air conditioner

The primary advantages of the TXV are that they perform better than the short tube orifice when

the airflow across the inside coil is low and when the amount of refrigerant in the unit is different

from that specified by the manufacturer. The effects of these parameters for a short tube orifice

and for a TXV are shown in Figures 1 and 2.

0.98

0.96

_ 0.94

( 0 92

, i 0.9

'

t 0.88

U' 0.86

E N 0.84

E 0.82

Z = 0.8 ·- TXV

X 0 78 -=-Short Tube Orifice

0.76

0.74

0.72

0.7

0.5 0.55 0.6 0.65 0.7 0.75 0.8 0.85 0.9 0.95 1

Air Flow (fraction of 400 cfm per ton)

Figure 1. Air Conditioner Efficiency vs. Evaporator Coil Air Flow

(derived generic relationship from multiple units at a variety of indoor and outdoor conditions -

see Appendix A)

PG&E TXV Impact Review DRAFT Oct. 23, 2000 Page 1-2 Proctor Engineering Group, Ltd.

EE-RM-STD-98-440 COMMENT 73LL

EE-RM/STO-9S-44o-1113 --- 1-v 

OvenJiew 

A short tube orifice provides a varying amount of superheat from 0 OF to over 30 OF. 

Performance Influences of the Metering Device 

The performance of the air conditioner is influenced by the interaction of the metering device 

with the following parameters: 

• Differing outdoor temperatures 

• Differing indoor conditions of humidity and temperature 

• Differing air flows across the inside coil 

• Differing amounts of refrigerant in the air conditioner 

The primary advantages of the TXV are that they perform better than the short tube orifice when 

the airflow across the inside coil is low and when the amount of refrigerant in the unit is different 

from that specified by the manufacturer. The effects of these parameters for a short tube orifice 

and for a TXV are shown in Figures 1 and 2. 

'2 

0.98 

0.96 

0.94· 

.£ 0.92· 

Q; ()' Q. 0.9 

c E .~ 't 0.88 .- 0 ffi ~ 0.86 

~«i N c:: 0.84· 

:=UJ 

~ ~ 0.82 o 0 

z § 0.8· 

~ ~ 0.78· 

0.76 

0.74 

072 

I---TXV l 

i-Short Tube Orifice I -----------------

0.7 .~----~-----+------~----+-----~----~------+-----~-----+----~ 

0.5 0.55 0.6 0.65 0.7 0.75 0.8 0.85 0.9 0.95 

Air Flow (fraction of 400 cfm per ton) 

Figure 1. Air Conditioner Efficiency vs. Evaporator Coil Air Flow 

(derived generic relationship from multiple units at a variety of indoor and outdoor conditions -

see Appendix A) 

PG&E TXV Impact Review DRAFT Oct. 23, 2000 Page 1-2 Proctor Engineering Group, Ltd. 

EE-RM/STO-9S-44o-1113 --- 1-v 

OvenJiew 

A short tube orifice provides a varying amount of superheat from 0 OF to over 30 OF. 

Performance Influences of the Metering Device 

The performance of the air conditioner is influenced by the interaction of the metering device 

with the following parameters: 

• Differing outdoor temperatures 

• Differing indoor conditions of humidity and temperature 

• Differing air flows across the inside coil 

• Differing amounts of refrigerant in the air conditioner 

The primary advantages of the TXV are that they perform better than the short tube orifice when 

the airflow across the inside coil is low and when the amount of refrigerant in the unit is different 

from that specified by the manufacturer. The effects of these parameters for a short tube orifice 

and for a TXV are shown in Figures 1 and 2. 

'2 

0.98 

0.96 

0.94· 

.£ 0.92· 

Q; ()' Q. 0.9 

c E .~ 't 0.88 .- 0 ffi ~ 0.86 

~«i N c:: 0.84· 

:=UJ 

~ ~ 0.82 o 0 

z § 0.8· 

~ ~ 0.78· 

0.76 

0.74 

072 

I---TXV l 

i-Short Tube Orifice I -----------------

0.7 .~----~-----+------~----+-----~----~------+-----~-----+----~ 

0.5 0.55 0.6 0.65 0.7 0.75 0.8 0.85 0.9 0.95 

Air Flow (fraction of 400 cfm per ton) 

Figure 1. Air Conditioner Efficiency vs. Evaporator Coil Air Flow 

(derived generic relationship from multiple units at a variety of indoor and outdoor conditions -

see Appendix A) 

PG&E TXV Impact Review DRAFT Oct. 23, 2000 Page 1-2 Proctor Engineering Group, Ltd. 
EE-RM/STD-98-440--1 L7 -

Overview

1.1

~0.9 x 

o 0.8

E ^*Short Tube Orifice

5 E 0.4

0.3

E0.2

0.1

0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 13 1.4

Refrigerant Charge (fraction of manufacturer's recommendation)

Figure 2. Air Conditioner Efficiency vs. Refrigerant Charge

(derived generic relationship from multiple units at a variety of conditions - see Appendix A)

Secondary Performance Influence of the Metering Device

The ability of the installing or servicing technician to determine whether the refrigerant level is

correct is influenced by the metering device.

The primary recommendation of most manufacturers is to check refrigerant charge on fixed

metering devices by measuring superheat and comparing that against a target value. The target

superheat varies with outdoor temperature (condenser air entering temperature) and the indoor

wet bulb temperature (evaporator air entering wet bulb). When the outdoor conditions are hot

and the indoor conditions are cool and dry, the target superheat is indeterminate. This means

that short tube orifice air conditioners cannot be easily checked for overcharge under common

conditions in the sunbelt states.

On the other hand, the primary recommendation of most manufacturers is to check refrigerant

level on TXVs by measuring subcooling and comparing it against a target value. There are few

limitations to the conditions under which this comparison can be made.

Because of this difference there is a potential for more air conditioners and heat pumps to be

charged properly when a TXV is installed.

Market Characteristics

Residential air conditioning is expanding into coastal and moderate climate areas. In addition air

conditioners are now the rule rather than the exception in new construction. The US Department

of Commerce reports that 84% of new single family homes completed in 1999 were equipped

with central air conditioning (U. S. DOE, 1999).

PG&E TXV Impact Review DRAFT Oct. 23, 2000 Page 1-3 Proctor Engineering Group, Ltd.

EE-RM-STD-98-440 COMMENT 73LL

Overuiew 

1.1 

~ 0.9 

~ "' 0.8 "g 

>,111 

g -g 0.7 . III III .;:; E 

iEE06' w 0 . 

<> "g III III .. 

~ 1U 0.5 . 

"'It: Ew 

OW 0.4 z-o 

c 

~ 0.3 

<> 

~ 0.2 

0.1 

o 

0.5 0.6 0.7 0.8 0.9 1.0 

EE-RM/STD-98-440-11 7?/ L--~ 

--

~TXV -----1 -ShortTube~ 

!--------1 --.---.1 

1.1 1.2 1.3 1.4 

Refrigerant Charge (fraction of manufacturer's recommendation) 

Figure 2, Air Conditioner Efficiency vs. Refrigerant Charge 

(derived generic relationship from multiple units at a variety of conditions - see Appendix A) 

Secondary Performance Influence of the Metering Device 

The ability of the installing or servicing technician to determine whether the refrigerant level is 

correct is influenced by the metering device. 

The primary recommendation of most manufacturers is to check refrigerant charge on fixed 

metering devices by measuring superheat and comparing that against a target value. The target 

superheat varies with outdoor temperature (condenser air entering temperature) and the indoor 

wet bulb temperature (evaporator air entering wet bulb). When the outdoor conditions are hot 

and the indoor conditions are cool and dry, the target superheat is indeterminate. This means 

that short tube orifice air conditioners cannot be easily checked for overcharge under common 

conditions in the sunbelt states. 

On the other hand, the primary recommendation of most manufacturers is to check refrigerant 

level on TXVs by measuring subcooling and comparing it against a target value. There are few 

limitations to the conditions under which this comparison can be made. 

Because of this difference there is a potential for more air conditioners and heat pumps to be 

charged properly when a TXV is installed. 

Market Characteristics 

Residential air conditioning is expanding into coastal and moderate climate areas. In addition air 

conditioners are now the rule rather than the exception in new construction. The US Department 

of Commerce reports that 84% of new single family homes completed in 1999 were equipped 

with central air conditioning (U. S. DOE, 1999). 

PG&E TXV Impact Review DRAFT Oct. 23, 2000 Page 1-3 Proctor Engineering Group, Ltd. 

Overuiew 

1.1 

~ 0.9 

~ "' 0.8 "g 

>,111 

g -g 0.7 . III III .;:; E 

iEE06' w 0 . 

<> "g III III .. 

~ 1U 0.5 . 

"'It: Ew 

OW 0.4 z-o 

c 

~ 0.3 

<> 

~ 0.2 

0.1 

o 

0.5 0.6 0.7 0.8 0.9 1.0 

EE-RM/STD-98-440-11 7?/ L--~ 

--

~TXV -----1 -ShortTube~ 

!--------1 --.---.1 

1.1 1.2 1.3 1.4 

Refrigerant Charge (fraction of manufacturer's recommendation) 

Figure 2, Air Conditioner Efficiency vs. Refrigerant Charge 

(derived generic relationship from multiple units at a variety of conditions - see Appendix A) 

Secondary Performance Influence of the Metering Device 

The ability of the installing or servicing technician to determine whether the refrigerant level is 

correct is influenced by the metering device. 

The primary recommendation of most manufacturers is to check refrigerant charge on fixed 

metering devices by measuring superheat and comparing that against a target value. The target 

superheat varies with outdoor temperature (condenser air entering temperature) and the indoor 

wet bulb temperature (evaporator air entering wet bulb). When the outdoor conditions are hot 

and the indoor conditions are cool and dry, the target superheat is indeterminate. This means 

that short tube orifice air conditioners cannot be easily checked for overcharge under common 

conditions in the sunbelt states. 

On the other hand, the primary recommendation of most manufacturers is to check refrigerant 

level on TXVs by measuring subcooling and comparing it against a target value. There are few 

limitations to the conditions under which this comparison can be made. 

Because of this difference there is a potential for more air conditioners and heat pumps to be 

charged properly when a TXV is installed. 

Market Characteristics 

Residential air conditioning is expanding into coastal and moderate climate areas. In addition air 

conditioners are now the rule rather than the exception in new construction. The US Department 

of Commerce reports that 84% of new single family homes completed in 1999 were equipped 

with central air conditioning (U. S. DOE, 1999). 

PG&E TXV Impact Review DRAFT Oct. 23, 2000 Page 1-3 Proctor Engineering Group, Ltd. 
EE-RM/STD-98-440 -;l 7

Overview

Only about 20% of new air conditioners use TXV metering devices and these are predominantly

used on replacement units as opposed to new construction (Personal Communication, Alco

Controls, 2000). The exceptions to this are the higher efficiency units with SEER 13 and above,

which generally use TXV metering (Manufacturers' Product Performance Data). These figures are

in substantial agreement with DOE's reverse engineered equipment data.

TXVs are rare in residential sized package units and lower efficiency heat pumps. They can be

used in these applications and are quite common on commercial rooftop package units.

The overall market penetration of TXVs in existing residences in California is approximately 13%

based on a database of 4,232 homes serviced in the year 2000 (CheckMe!® Database 2000).

Residential air conditioners generally operate at off design conditions (Neme et al. 1999). That is,

most units operate with low airflow across the inside coil, an incorrect amount of refrigerant, or

both.

Various studies (ibid.) show a near normal distribution of airflows with a standard deviation of

80 cfm per ton. Data on existing construction show a mean airflow between 270 and 350 cfm per

ton.

The CheckMe! database has information on the distribution of refrigerant charge. These data

(Figure 3) show 62% of the units mischarged. This figure is exactly the same as the average of

earlier studies summarized in Neme et al.

62% of Population Mischarged 4 0 % .................... . ...... . ....... .... ........ l ...... ... ... . ..... . .... ..

Correct Charge

35%

- 30%

o 25%

20%_ I -- _ i15%

°S U ndercharge Overcharge

15% _l l ,___ O r g

0%

0.2 0.3 0.5 0.7 0.9 1.1 1.3 1.5 1.8

Refrigerant Charge

(fraction of correct charge)

Figure 3. Refrigerant Charge Distribution

(from CheckMe! Database)

Cost

The retail cost of TXVs is between $45 and $50 from parts supply houses (Personnel

Communications, 2000). Residential service/installation companies surveyed quoted $100 for a

TXV installed. According to one TXV manufacturer (ibid.) the differential price to an air

conditioner manufacturer would be between $8 and $11.

PG&E TXV Impact Review DRAFT Oct. 23, 2000 Page 1-4 Proctor Engineering Group, Ltd.

EE-RM-STD-98-440 COMMENT 73LL

EE-RM/STO-9S-440""1r1?:>, L~ 

Overview 

Only about 20% of new air conditioners use TXV metering devices and these are predominantly 

used on replacement units as opposed to new construction (Personal Communication, Alco 

Controls, 2000), The exceptions to this are the higher efficiency units with SEER 13 and above, 

which generally use TXV metering (Manufacturers' Product Performance Data), These figures are 

in substantial agreement with DOE's reverse engineered equipment data, 

TXVs are rare in residential sized package units and lower efficiency heat pumps, They can be 

used in these applications and are quite common on commercial rooftop package units, 

The overall market penetration of TXVs in existing residences in California is approximately 13% 

based on a database of 4,232 homes serviced in the year 2000 (CheckMe!® Database 2000), 

Residential air conditioners generally operate at off design conditions (Neme et aL 1999), That is, 

most units operate with low airflow across the inside coil, an incorrect amount of refrigerant, or 

both, 

Various studies (ibid,) show a near normal distribution of airflows with a standard deviation of 

80 cfm per ton, Data on existing construction show a mean airflow between 270 and 350 cfm per 

ton. 

The CheckMe! database has information on the distribution of refrigerant charge, These data 

(Figure 3) show 62 % of the units mischarged, This figure is exactly the same as the average of 

earlier studies summarized in Neme et aL 

62% of Population Mischarged 40% ------------- --- ----------------------- ------------------- "- -1 

35% --------------------- --Correct Charge 

c: 

,2 30% -1--------------- --------------! n; 

:; 

g. 25%- c.. 

~ 20% -------------1 

I-

-o 

"E 

15% ------------------

Q) 

(.) 

iii 

c.. 10% 

5%-1--------

0_2 0_3 0,5 0.7 0.9 

_IHI _____________ i 

:li!l: ' l!tt Overcharge 

-I,,",,· --.---------; 

-- '~ __ I 

i ;- I' 

f I , 

1.1 1.3 1.5 1.8 

Refrigerant Charge 

(fraction of correct charge) 

Figure 3. Refrigerant Charge Distribution 

(from CheckMe! Database) 

Cost 

The retail cost of TXVs is between $45 and $50 from parts supply houses (Personnel 

Communications, 2000). Residential service/installation companies surveyed quoted $100 for a 

TXV installed. According to one TXV manufacturer (ibid.) the differential price to an air 

conditioner manufacturer would be between $8 and $11. 

PG&E TXV Impact Review DRAFT Oct. 23,2000 Page 1-4 Proctor Engineering Group, Ltd, 

EE-RM/STO-9S-440""1r1?:>, L~ 

Overview 

Only about 20% of new air conditioners use TXV metering devices and these are predominantly 

used on replacement units as opposed to new construction (Personal Communication, Alco 

Controls, 2000), The exceptions to this are the higher efficiency units with SEER 13 and above, 

which generally use TXV metering (Manufacturers' Product Performance Data), These figures are 

in substantial agreement with DOE's reverse engineered equipment data, 

TXVs are rare in residential sized package units and lower efficiency heat pumps, They can be 

used in these applications and are quite common on commercial rooftop package units, 

The overall market penetration of TXVs in existing residences in California is approximately 13% 

based on a database of 4,232 homes serviced in the year 2000 (CheckMe!® Database 2000), 

Residential air conditioners generally operate at off design conditions (Neme et aL 1999), That is, 

most units operate with low airflow across the inside coil, an incorrect amount of refrigerant, or 

both, 

Various studies (ibid,) show a near normal distribution of airflows with a standard deviation of 

80 cfm per ton, Data on existing construction show a mean airflow between 270 and 350 cfm per 

ton. 

The CheckMe! database has information on the distribution of refrigerant charge, These data 

(Figure 3) show 62 % of the units mischarged, This figure is exactly the same as the average of 

earlier studies summarized in Neme et aL 

62% of Population Mischarged 40% ------------- --- ----------------------- ------------------- "- -1 

35% --------------------- --Correct Charge 

c: 

,2 30% -1--------------- --------------! n; 

:; 

g. 25%- c.. 

~ 20% -------------1 

I-

-o 

"E 

15% ------------------

Q) 

(.) 

iii 

c.. 10% 

5%-1--------

0_2 0_3 0,5 0.7 0.9 

_IHI _____________ i 

:li!l: ' l!tt Overcharge 

-I,,",,· --.---------; 

-- '~ __ I 

i ;- I' 

f I , 

1.1 1.3 1.5 1.8 

Refrigerant Charge 

(fraction of correct charge) 

Figure 3. Refrigerant Charge Distribution 

(from CheckMe! Database) 

Cost 

The retail cost of TXVs is between $45 and $50 from parts supply houses (Personnel 

Communications, 2000). Residential service/installation companies surveyed quoted $100 for a 

TXV installed. According to one TXV manufacturer (ibid.) the differential price to an air 

conditioner manufacturer would be between $8 and $11. 

PG&E TXV Impact Review DRAFT Oct. 23,2000 Page 1-4 Proctor Engineering Group, Ltd, 
EE-RM/STD-98-440- -. L

OvervZiew

Benefit Methodology

The benefit of TXVs on the average SEER of units was determined by examining the published

performance data for identical matched indoor and outdoor units with orifice and with TXV

metering devices.

The benefits of TXVs in the performance of air conditioners in off design conditions were

estimated in a three-step process. First, laboratory test data for TXV and short tube orifice

equipped air conditioners were analyzed and generalized performance maps were developed.

Second, existing field data on "off-design" conditions were analyzed and distributions of airflow

and amount of charge were determined. Third, the distributions were applied to the performance

maps and the resultant differences over the whole population were estimated.

Benefits

Replacement of short tube orifices with TXVs would have a number of energy and peak electrical

consumption benefits. Using data from laboratory tests reported in the bibliography as well as

the distribution of incorrect charge and airflow from the reports and CheckMe! database,

replacement of short tube orifices will have the following effects:

· Reduced energy consumption of approximately 4.7% as reflected in an improved SEER1.

· An additional reduced energy consumption of approximately 11% or more due to the TXVs

tolerance of incorrect refrigerant charge and low airflow.

· An average peak load reduction of 5.7% or more due to the TXVs tolerance to low airflow

and undercharge.

o A simplified charge checking methodology that is applicable over a wider range of

conditions.

Note that this improvement will be integrated into the reported SEER and is not additive to

SEER.

PG&E TXV Impact Review DRAFT Oct. 23, 2000 Page 1-5 Proctor Engineering Group, Ltd.

EE-RM-STD-98-440 COMMENT 73LL

EE-RM/STD-98-440 .. 1( 1~·- tLOverview 

Benefit Methodology 

The benefit of TXVs on the average SEER of units was determined by examining the published 

performance data for identical matched indoor and outdoor units with orifice and with TXV 

metering devices. 

The benefits of TXVs in the performance of air conditioners in off design conditions were 

estimated in a three-step process. First, laboratory test data for TXV and short tube orifice 

equipped air conditioners were analyzed and generalized performance maps were developed. 

Second, existing field data on "off-design" conditions were analyzed and distributions of airflow 

and amount of charge were determined. Third, the distributions were applied to the performance 

maps and the resultant differences over the whole population were estimated. 

Benefits 

Replacement of short tube orifices with TXVs would have a number of energy and peak electrical 

consumption benefits. Using data from laboratory tests reported in the bibliography as well as 

the distribution of incorrect charge and airflow from the reports and CheckMe! database, 

replacement of short tube orifices will have the following effects: 

• Reduced energy consumption of approximately 4.7% as reflected in an improved SEERl. 

• An additional reduced energy consumption of approximately 11 % or more due to the TXVs 

tolerance of incorrect refrigerant charge and low airflow. 

• An average peak load reduction of 5.7% or more due to the TXVs tolerance to low airflow 

and undercharge. 

• A simplified charge checking methodology that is applicable over a wider range of 

conditions. 

1 Note that this improvement will be integrated into the reported SEER and is not additive to 

SEER. 

PG&E TXV Impact Review DRAFT Oct. 23,2000 Page 1-5 Proctor Engineering Group, Ltd. 

EE-RM/STD-98-440 .. 1( 1~·- tLOverview 

Benefit Methodology 

The benefit of TXVs on the average SEER of units was determined by examining the published 

performance data for identical matched indoor and outdoor units with orifice and with TXV 

metering devices. 

The benefits of TXVs in the performance of air conditioners in off design conditions were 

estimated in a three-step process. First, laboratory test data for TXV and short tube orifice 

equipped air conditioners were analyzed and generalized performance maps were developed. 

Second, existing field data on "off-design" conditions were analyzed and distributions of airflow 

and amount of charge were determined. Third, the distributions were applied to the performance 

maps and the resultant differences over the whole population were estimated. 

Benefits 

Replacement of short tube orifices with TXVs would have a number of energy and peak electrical 

consumption benefits. Using data from laboratory tests reported in the bibliography as well as 

the distribution of incorrect charge and airflow from the reports and CheckMe! database, 

replacement of short tube orifices will have the following effects: 

• Reduced energy consumption of approximately 4.7% as reflected in an improved SEERl. 

• An additional reduced energy consumption of approximately 11 % or more due to the TXVs 

tolerance of incorrect refrigerant charge and low airflow. 

• An average peak load reduction of 5.7% or more due to the TXVs tolerance to low airflow 

and undercharge. 

• A simplified charge checking methodology that is applicable over a wider range of 

conditions. 

1 Note that this improvement will be integrated into the reported SEER and is not additive to 

SEER. 

PG&E TXV Impact Review DRAFT Oct. 23,2000 Page 1-5 Proctor Engineering Group, Ltd. 
DRAFT EE-RM/STD-98-440-' 7 - L L

CONCLUSIONS

Proctor Engineering Group concludes that building residential air conditioners with thermostatic

expansion valves as opposed the more common short tube orifice will save energy and reduce

the diversified electrical power load on peak. These effects are largely due to the improved

tolerance to common field problems of incorrect refrigerant charge and low airflow across the

evaporator coil.

The cost of building units to this specification will depend on whether it is done at the factory

(shipped already attached to the evaporator coil) or installed by the contractor in the field. The

low side differential cost is $15 at the factory. The high side differential cost is $100 in the field.

PG&E TXV Impact Review DRAFT Oct. 23, 2000 Page 2-1 Proctor Engineering Group, Ltd.

EE-RM-STD-98-440 COMMENT 73LL

DRAFT EE-RM/STD-98-440-:# 13 -' L L 

CONCLUSIONS 

Proctor Engineering Group concludes that building residential air conditioners with thermostatic 

expansion valves as opposed the more common short tube orifice will save energy and reduce 

the diversified electrical power load on peak. These effects are largely due to the improved 

tolerance to common field problems of incorrect refrigerant charge and low airflow across the 

evaporator coil. 

The cost of building units to this specification will depend on whether it is done at the factory 

(shipped already attached to the evaporator coil) or installed by the contractor in the field. The 

low side differential cost is $15 at the factory. The high side differential cost is $100 in the field. 

PG&E TXV Impact Review DRAFT Oct. 23, 2000 Page 2-1 Proctor Engineering Group, Ltd. 

DRAFT EE-RM/STD-98-440-:# 13 -' L L 

CONCLUSIONS 

Proctor Engineering Group concludes that building residential air conditioners with thermostatic 

expansion valves as opposed the more common short tube orifice will save energy and reduce 

the diversified electrical power load on peak. These effects are largely due to the improved 

tolerance to common field problems of incorrect refrigerant charge and low airflow across the 

evaporator coil. 

The cost of building units to this specification will depend on whether it is done at the factory 

(shipped already attached to the evaporator coil) or installed by the contractor in the field. The 

low side differential cost is $15 at the factory. The high side differential cost is $100 in the field. 

PG&E TXV Impact Review DRAFT Oct. 23, 2000 Page 2-1 Proctor Engineering Group, Ltd. 
DRAFT EE-RM/STD-98-440f- ['"

BIBLIOGRAPHY

ALCO Controls Division, Emerson Electric Company, St. Louis, Missouri, "Refrigeration and Air

Conditioning Flow Control", Catalogue 28, p. 298 - 310, "Fundamentals of Thermo® Expansion

Valves".

ARI Directory of Certified Unitary Equipment Standards 210/240/270. Published by AirConditioning Refrigeration Institute (ARI) twice each year.

Bain, Joel A., Dennis L. O'Neal, Michael A. Davis, Angel G. Rodriquez, "The Effect of Hardware

Configuration on the Performance of Residential Air Conditioning Systems At High Outdoor

Ambient Temperatures", EPRI Final Report, November 1995, prepared by Energy Systems

Laboratory, Texas A&M University.

CheckMe!® Database, Electronic recorded data for 4,232 California homes serviced in the year

2000, Proctor Engineering Group

Energy Design Update, "Inadequate Air Flow Torpedoes Air Conditioner and Heat Pump

Performance", June 1998, p. 11-12.

Farzad, Mohsen, "Modeling The Effects of Refrigerant Charging on Air Conditioner Performance

Characteristics For Three Expansion Devices", pH Thesis, Mechanical Engineering, Texas A& M

University, August 1990.

Farzad, Mohsen and Dennis L. O'Neal, "An Evaluation of Improper Charge on the Performance

of a Split System Air Conditioner with Capillary Tube Expansion", ESL/CON/88-1, July 1988,

Texas A&M University.

Farzad, M. and D. L. O'Neal, "Influence of the Expansion Device on Air-Conditioner System

Performance Under a Range of Charging Conditions" ASHRAE Paper 3622, ASHRAE

Transactions, January 1993, p. 3 - 13.

Manufacturers Product Performance Data from -

o Air Pro/Coleman (Evcon Industries)

* Amana Corporation

* Carrier Corporation

o Lennox Industries

* Rudd (Rheem Corporation)

* Tempstar/Heil (International Comfort Products Corporation)

* The Trane Company, Unitary Products Group

* York Corporation

PG&E TXV Impact Review DRAFT Oct. 23, 2000 Page 3-1 Proctor Engineering Group, Ltd.

EE-RM-STD-98-440 COMMENT 73LL

DRAFT 

BIBLIOGRAPHY 

ALCO Controls Division, Emerson Electric Company, St. Louis, Missouri, "Refrigeration and Air 

Conditioning Flow Control", Catalogue 28, p. 298 - 310, "Fundamentals of Thermo® Expansion 

Valves". 

ARI Directory of Certified Unitary Equipment Standards 210/240/270. Published by AirConditioning Refrigeration Institute (ARI) twice each year. 

Bain, Joel A., Dennis L. O'Neal, Michael A. Davis, Angel G. Rodriquez, "The Effect of Hardware 

Configuration on the Performance of Residential Air Conditioning Systems At High Outdoor 

Ambient Temperatures", EPRI Final Report, November 1995, prepared by Energy Systems 

Laboratory, Texas A&M University. 

CheckMe!® Database, Electronic recorded data for 4,232 California homes serviced in the year 

2000, Proctor Engineering Group 

Energy Design Update, "Inadequate Air Flow Torpedoes Air Conditioner and Heat Pump 

Performance", June 1998, p. 11-12. 

Farzad, Mohsen, "Modeling The Effects of Refrigerant Charging on Air Conditioner Performance 

Characteristics For Three Expansion Devices", pH Thesis, Mechanical Engineering, Texas A& M 

University, August 1990. 

Farzad, Mohsen and Dennis L. O'Neal, "An Evaluation of Improper Charge on the Performance 

of a Split System Air Conditioner with Capillary Tube Expansion", ESL/CON/88-1, July 1988, 

Texas A&M University. 

Farzad, M. and D. L. O'Neal, "Influence of the Expansion Device on Air-Conditioner System 

Performance Under a Range of Charging Conditions" ASHRAE Paper 3622, ASH RAE 

Transactions, January 1993, p. 3 -13. 

Manufacturers Product Performance Data from -

• Air Pro/Coleman (Evcon Industries) 

• Amana Corporation 

• Carrier Corporation 

• Lennox Industries 

• Rudd (Rheem Corporation) 

• Tempstar /Heil (International Comfort Products Corporation) 

• The Trane Company, Unitary Products Group 

• York Corporation 

PG&E TXV Impact Review DRAFT Oct. 23, 2000 Page 3-1 Proctor Engineering Group, Ltd. 

DRAFT 

BIBLIOGRAPHY 

ALCO Controls Division, Emerson Electric Company, St. Louis, Missouri, "Refrigeration and Air 

Conditioning Flow Control", Catalogue 28, p. 298 - 310, "Fundamentals of Thermo® Expansion 

Valves". 

ARI Directory of Certified Unitary Equipment Standards 210/240/270. Published by AirConditioning Refrigeration Institute (ARI) twice each year. 

Bain, Joel A., Dennis L. O'Neal, Michael A. Davis, Angel G. Rodriquez, "The Effect of Hardware 

Configuration on the Performance of Residential Air Conditioning Systems At High Outdoor 

Ambient Temperatures", EPRI Final Report, November 1995, prepared by Energy Systems 

Laboratory, Texas A&M University. 

CheckMe!® Database, Electronic recorded data for 4,232 California homes serviced in the year 

2000, Proctor Engineering Group 

Energy Design Update, "Inadequate Air Flow Torpedoes Air Conditioner and Heat Pump 

Performance", June 1998, p. 11-12. 

Farzad, Mohsen, "Modeling The Effects of Refrigerant Charging on Air Conditioner Performance 

Characteristics For Three Expansion Devices", pH Thesis, Mechanical Engineering, Texas A& M 

University, August 1990. 

Farzad, Mohsen and Dennis L. O'Neal, "An Evaluation of Improper Charge on the Performance 

of a Split System Air Conditioner with Capillary Tube Expansion", ESL/CON/88-1, July 1988, 

Texas A&M University. 

Farzad, M. and D. L. O'Neal, "Influence of the Expansion Device on Air-Conditioner System 

Performance Under a Range of Charging Conditions" ASHRAE Paper 3622, ASH RAE 

Transactions, January 1993, p. 3 -13. 

Manufacturers Product Performance Data from -

• Air Pro/Coleman (Evcon Industries) 

• Amana Corporation 

• Carrier Corporation 

• Lennox Industries 

• Rudd (Rheem Corporation) 

• Tempstar /Heil (International Comfort Products Corporation) 

• The Trane Company, Unitary Products Group 

• York Corporation 

PG&E TXV Impact Review DRAFT Oct. 23, 2000 Page 3-1 Proctor Engineering Group, Ltd. 
EE-RM/STD-98-440--: 1'9 LK.

Bibliography

Neal, C. Leon, P. E., "Field Adjusted SEER [SEERFA] - Residential Buildings: Technologies,

Design, and Performance Analysis", Proceedings of 1998 ACEEE Summer Study on Energy

Efficiency in Buildings, Vol. 1, p. 1.197 - 1.209.

Neme, Chris, John Proctor, and Steve Nadel, "National Energy Savings Potential From

Addressing Residential HVAC Installation Problems", February 1999, Prepared as a part of the U.

S. Environmental Protection Agency's Energy Star Program.

Palami, Manivannan, Dr. Dennis O'Neal, and Dr. Jeff Haberl, "The Effect of Reduced Evaporator

Air Flow on the Performance of a Residential Central Air Conditioner", Proceedings of the Eighth

Annual Symposium on Improving Building Systems in Hot and Humid Climates, Texas A&M

University, May 13 - 14, 1992, p. 20 - 26.

Parker, Danny S., John R. Sherwin, Richard A. Ranstad, and Don B. Shirey III, "Impact of

Evaporator Coil Airflow in Residential Air-Conditioning Systems", ASHRAE BN-97-2-1,

ASHRAE Transactions 1997, v. 103, pt. 2.

Patenaude, Andre, "Refrigeration Fluid Flow Controls and System Troubleshooting Guide",

ALCO Controls Division, Emerson Electric Company, December 1990.

Personal Communications

* Sporlan Valve Company

* Alco Controls, Buzz Schaeffer, May 30, 2000

* Alco Controls, Buzz Schaeffer, May 31, 2000

Proctor, J. P., "Field Measurement of New Residential Air Conditioners in Phoenix, Arizona",

ASHRAE BN-97-2-2, also ASHRAE Transactions 1997, vol. 103, Pt. 2, p. 406 - 415.

Proctor, J. and P. Albright, "Sizing Air Conditioners: If Bigger Is Not Better, What Is?", Home

Energy Magazine, Sept./Oct. 1996, p. 13 - 18.

Proctor, John, Tom Downey, Curtis Boecker, Zinoviy Katsnelson, George Peterson, and Dennis

O'Neal., "Investigation of Peak Load Impacts of High SEER Residential HVAC Units - Assembly,

Testing, and investigation of a Reduced Peak Load Air Conditioner", Pacific Gas and Electric

Company, Research and Development Department June, 1996

Rodriquez, Angel Gerardo, "Effect of Refrigerant Charge, Duct Leakage, and Evaporator Air

Flow on the High Temperature Performance of Air Conditioners and Heat Pumps", M S Thesis,

Mechanical Engineering Department, Texas A&M University, August 1995.

Rodriquez, Angel G., Dennis L. O'Neal, Joel A. Bain, and Michael A. Davis, "The Effect of

Refrigerant Charge, Duct Leakage, and Evaporator Air Flow on the High Temperature

Performance of Air Conditioners and Heat Pumps", May 1995, Draft Final Report, [Submitted to

EPRI]

Sporlan Valve Company, 206 Lange Drive, Washington, Missouri 63090, (a) Educational Bulletin

10-9 Thermostatic Expansion Valves - Theory of Operation, Application and Selection, October

1995, (b) Educational Bulletin 10-11 Thermostatic Expansion Valves - Installation, Field Service

and Assembly, September 1996.

PG&E TXV Impact Review DRAFT Oct. 23, 2000 Page 3-2 Proctor Engineering Group, Ltd.

EE-RM-STD-98-440 COMMENT 73LL

EE-RM/STD-98-440 --J): 10.- LL/ 

Bibliography 

Neal, C. Leon, P. E., "Field Adjusted SEER [SEERFA] - Residential Buildings: Technologies, 

Design, and Performance Analysis", Proceedings of 1998 ACEEE Summer Study on Energy 

Efficiency in Buildings, Vol. 1, p. 1.197 -1.209. 

Neme, Chris, John Proctor, and Steve Nadel, "National Energy Savings Potential From 

Addressing Residential HVAC Installation Problems", February 1999, Prepared as a part of the U. 

S. Environmental Protection Agency's Energy Star Program. 

Palami, Manivannan, Dr. Dennis O'Neal, and Dr. Jeff Haberl, "The Effect of Reduced Evaporator 

Air Flow on the Performance of a Residential Central Air Conditioner", Proceedings of the Eighth 

Annual Symposium on Improving Building Systems in Hot and Humid Climates, Texas A&M 

University, May 13 -14, 1992, p. 20 - 26. 

Parker, Danny S., John R. Sherwin, Richard A. Ranstad, and Don B. Shirey IIt "Impact of 

Evaporator Coil Airflow in Residential Air-Conditioning Systems", ASHRAE BN-97-2-1, 

ASHRAE Transactions 1997, v. 103, pt. 2. 

Patenaude, Andre, "Refrigeration Fluid Flow Controls and System Troubleshooting Guide", 

ALCO Controls Division, Emerson Electric Company, December 1990. 

Personal Communications 

• Sporlan Valve Company 

• Ako Controls, Buzz Schaeffer, May 30, 2000 

• Ako Controls, Buzz Schaeffer, May 31, 2000 

Proctor, J. P., "Field Measurement of New Residential Air Conditioners in Phoenix, Arizona", 

ASHRAE BN-97-2-2, also ASHRAE Transactions 1997, vol. 103, Pt. 2, p. 406 - 415. 

Proctor, J. and P. Albright, "Sizing Air Conditioners: If Bigger Is Not Better, What Is?", Home 

Energy Magazine, Sept./Oct. 1996, p. 13 -18. 

Proctor, John, Tom Downey, Curtis Boecker, Zinoviy Katsnelson, George Peterson, and Dennis 

O'Neal., "Investigation of Peak Load Impacts of High SEER Residential HV AC Units - Assembly, 

Testing, and investigation of a Reduced Peak Load Air Conditioner", Pacific Gas and Electric 

Company, Research and Development Department June, 1996 

Rodriquez, Angel Gerardo, "Effect of Refrigerant Charge, Duct Leakage, and Evaporator Air 

Flow on the High Temperature Performance of Air Conditioners and Heat Pumps", M S Thesis, 

Mechanical Engineering Department, Texas A&M University, August 1995. 

Rodriquez, Angel G., Dennis L. O'Neal, Joel A. Bain, and Michael A. Davis, "The Effect of 

Refrigerant Charge, Duct Leakage, and Evaporator Air Flow on the High Temperature 

Performance of Air Conditioners and Heat Pumps", May 1995, Draft Final Report, [Submitted to 

EPRI] 

Sporlan Valve Company, 206 Lange Drive, Washington, Missouri 63090, (a) Educational Bulletin 

10-9 Thermostatic Expansion Valves - Theory of Operation, Application and Selection, October 

1995, (b) Educational Bulletin 10-11 Thermostatic Expansion Valves - Installation, Field Service 

and Assembly, September 1996. 

PG&E TXV Impact Review DRAFT Oct. 23, 2000 Page 3-2 Proctor Engineering Group, Ltd. 

EE-RM/STD-98-440 --J): 10.- LL/ 

Bibliography 

Neal, C. Leon, P. E., "Field Adjusted SEER [SEERFA] - Residential Buildings: Technologies, 

Design, and Performance Analysis", Proceedings of 1998 ACEEE Summer Study on Energy 

Efficiency in Buildings, Vol. 1, p. 1.197 -1.209. 

Neme, Chris, John Proctor, and Steve Nadel, "National Energy Savings Potential From 

Addressing Residential HVAC Installation Problems", February 1999, Prepared as a part of the U. 

S. Environmental Protection Agency's Energy Star Program. 

Palami, Manivannan, Dr. Dennis O'Neal, and Dr. Jeff Haberl, "The Effect of Reduced Evaporator 

Air Flow on the Performance of a Residential Central Air Conditioner", Proceedings of the Eighth 

Annual Symposium on Improving Building Systems in Hot and Humid Climates, Texas A&M 

University, May 13 -14, 1992, p. 20 - 26. 

Parker, Danny S., John R. Sherwin, Richard A. Ranstad, and Don B. Shirey IIt "Impact of 

Evaporator Coil Airflow in Residential Air-Conditioning Systems", ASHRAE BN-97-2-1, 

ASHRAE Transactions 1997, v. 103, pt. 2. 

Patenaude, Andre, "Refrigeration Fluid Flow Controls and System Troubleshooting Guide", 

ALCO Controls Division, Emerson Electric Company, December 1990. 

Personal Communications 

• Sporlan Valve Company 

• Ako Controls, Buzz Schaeffer, May 30, 2000 

• Ako Controls, Buzz Schaeffer, May 31, 2000 

Proctor, J. P., "Field Measurement of New Residential Air Conditioners in Phoenix, Arizona", 

ASHRAE BN-97-2-2, also ASHRAE Transactions 1997, vol. 103, Pt. 2, p. 406 - 415. 

Proctor, J. and P. Albright, "Sizing Air Conditioners: If Bigger Is Not Better, What Is?", Home 

Energy Magazine, Sept./Oct. 1996, p. 13 -18. 

Proctor, John, Tom Downey, Curtis Boecker, Zinoviy Katsnelson, George Peterson, and Dennis 

O'Neal., "Investigation of Peak Load Impacts of High SEER Residential HV AC Units - Assembly, 

Testing, and investigation of a Reduced Peak Load Air Conditioner", Pacific Gas and Electric 

Company, Research and Development Department June, 1996 

Rodriquez, Angel Gerardo, "Effect of Refrigerant Charge, Duct Leakage, and Evaporator Air 

Flow on the High Temperature Performance of Air Conditioners and Heat Pumps", M S Thesis, 

Mechanical Engineering Department, Texas A&M University, August 1995. 

Rodriquez, Angel G., Dennis L. O'Neal, Joel A. Bain, and Michael A. Davis, "The Effect of 

Refrigerant Charge, Duct Leakage, and Evaporator Air Flow on the High Temperature 

Performance of Air Conditioners and Heat Pumps", May 1995, Draft Final Report, [Submitted to 

EPRI] 

Sporlan Valve Company, 206 Lange Drive, Washington, Missouri 63090, (a) Educational Bulletin 

10-9 Thermostatic Expansion Valves - Theory of Operation, Application and Selection, October 

1995, (b) Educational Bulletin 10-11 Thermostatic Expansion Valves - Installation, Field Service 

and Assembly, September 1996. 

PG&E TXV Impact Review DRAFT Oct. 23, 2000 Page 3-2 Proctor Engineering Group, Ltd. 
EE-RM/STD-98.4404 1'5- Lb

Bibliography

U. S. Department of Energy, Technical Support Document: Energy Efficiency Standards For

Consumer Products: Residential Central Air Conditioners and Heat Pumps, November 1999, p. 2

- 3.

U. S. Government, Federal Register, Vol. 64, No. 226, Wednesday, November 24, 1999, Proposed

Rules Department of Energy, Office of Energy Efficiency and Renewable Energy, 10CFR Part 430

[Docket No. EE-RM/STD-98-440], pp. 66306 - 66340.

www.ari.org/ pr/2000/080700ships.html, "Hot Shipments For Air Conditioning Manufacturers",

Ed Dooley, Air-Conditioning & Refrigeration Institute, Koldfax, August 2000.

PG&E TXV Impact Review DRAFT Oct. 23, 2000 Page 3-3 Proctor Engineering Group, Ltd.

EE-RM-STD-98-440 COMMENT 73LL

Bibliography 

u. S. Department of Energy, Technical Support Document: Energy Efficiency Standards For 

Consumer Products: Residential Central Air Conditioners and Heat Pumps, November 1999, p. 2 

- 3. 

u. S. Government, Federal Register, Vol. 64, No. 226, Wednesday, November 24, 1999, Proposed 

Rules Department of Energy, Office of Energy Efficiency and Renewable Energy, 10CFR Part 430 

[Docket No. EE-RMjSTD-98-440], pp. 66306 - 66340. 

www.ari.org/pr/2000/080700ships.html. "Hot Shipments For Air Conditioning Manufacturers", 

Ed Dooley, Air-Conditioning & Refrigeration Institute, Koldfax, August 2000. 

PG&E TXV Impact Review DRAFT Oct. 23, 2000 Page 3-3 Proctor Engineering Group, Ltd. 

Bibliography 

u. S. Department of Energy, Technical Support Document: Energy Efficiency Standards For 

Consumer Products: Residential Central Air Conditioners and Heat Pumps, November 1999, p. 2 

- 3. 

u. S. Government, Federal Register, Vol. 64, No. 226, Wednesday, November 24, 1999, Proposed 

Rules Department of Energy, Office of Energy Efficiency and Renewable Energy, 10CFR Part 430 

[Docket No. EE-RMjSTD-98-440], pp. 66306 - 66340. 

www.ari.org/pr/2000/080700ships.html. "Hot Shipments For Air Conditioning Manufacturers", 

Ed Dooley, Air-Conditioning & Refrigeration Institute, Koldfax, August 2000. 

PG&E TXV Impact Review DRAFT Oct. 23, 2000 Page 3-3 Proctor Engineering Group, Ltd. 
DLRAFT US-^ L^ ~DRAFT 1 EE-RM/STD-98-440 _3o LL

GLOSSARY OF TERMS

PG&E TXV Impact Review DRAFT Oct. 23, 2000 Page 4-1 Proctor Engineering Group, Ltd.

EE-RM-STD-98-440 COMMENT 73LL

DRAFT 

GLOSSARY OF TERMS 

PG&E TXV Impact Review DRAFT Oct. 23, 2000 Page 4-1 Proctor Engineering Group, Ltd. 

DRAFT 

GLOSSARY OF TERMS 

PG&E TXV Impact Review DRAFT Oct. 23, 2000 Page 4-1 Proctor Engineering Group, Ltd. 
DRAFT

EE-RM/STD.98.44 0 LL

APPENDIX A. METHODOLOGY

Effect on SEER

The benefit of TXVs on the average SEER of units was determined by examining the published

performance data for identical matched indoor and outdoor units with orifice and with TXV

metering devices.

Effect at field conditions

The benefits of TXVs in the performance of air conditioners in off design conditions were

estimated in a three-step process. First, laboratory test data for TXV and short tube orifice

equipped air conditioners were analyzed and generalized performance maps were developed.

Second, existing field data on "off-design" conditions were analyzed and distributions of airflow

and amount of charge were determined. Third, the distributions were applied to the performance

maps and the resultant differences over the whole population were estimated.

Laboratory Test Data for Both Metering Devices

There are a limited number of data sets for air conditioners run at incorrect charge, low airflow,

and a variety of test conditions. Available data includes Bain et al. 1995, Proctor et al. 1996, and

Rodriquez et al. May 1995. In all cases the largest compilation of data was used to produce the

performance equations used in the analysis. In all cases the EER was normalized to the EER at

correct charge, normal airflow (taken as 400 cfm per ton wet coil), and the specified indoor /

outdoor conditions.

Charge Effect on TXV Units The effect of charge on normalized EER was found to be only mildly

effected by airflow and outdoor temperatures. The following least squares fit to the data includes

27 observations and all three regression coefficients are significant at the 95% level.

EERnorml = 2.289767 - 1.294853 * perchg +1.356132 * LN(perchg)

where:

EERnorml is the ratio of the EER and the maximum EER at those outdoor and air flow

conditions

perchg is the ratio of the installed charge to the correct charge

Charge Effect on Short Tube Orifice Units The effect of charge on normalized EER was found to

be only mildly effected by airflow and outdoor temperatures. The following least squares fit to

the data includes 21 observations and all three regression coefficients are significant at the 95%

level.

EERnorml =5.082403 - 4.100056 * perchg + 4.619659 * LN(perchg)

PG&E TXV Impact Review DRAFT Oct. 23, 2000 Page A-' Proctor Engineering Group, Ltd.

EE-RM-STD-98-440 COMMENT 73LL

DRAFT 

APPENDIX A. METHODOLOGY 

Effect on SEER 

The benefit of TXVs on the average SEER of units was determined by examining the published 

performance data for identical matched indoor and outdoor units with orifice and with TXV 

metering devices. 

Effect at field conditions 

The benefits of TXVs in the performance of air conditioners in off design conditions were 

estimated in a three-step process. First, laboratory test data for TXV and short tube orifice 

equipped air conditioners were analyzed and generalized performance maps were developed. 

Second, existing field data on "off-design" conditions were analyzed and distributions of airflow 

and amount of charge were determined. Third, the distributions were applied to the performance 

maps and the resultant differences over the whole population were estimated. 

Laboratory Test Data for Both Metering Devices 

There are a limited number of data sets for air conditioners run at incorrect charge, low airflow, 

and a variety of test conditions. Available data includes Bain et al. 1995, Proctor et al. 1996, and 

Rodriquez et al. May 1995. In all cases the largest compilation of data was used to produce the 

performance equations used in the analysis. In all cases the EER was normalized to the EER at 

correct charge, normal airflow (taken as 400 dm per ton wet coil), and the specified indoor / 

outdoor conditions. 

Charge Effect on TXV Units The effect of charge on normalized EER was found to be only mildly 

effected by airflow and outdoor temperatures. The following least squares fit to the data includes 

27 observations and all three regression coefficients are significant at the 95% level. 

EERnorm1 = 2.289767 -1.294853 * perchg +1.356132 * LN(perchg) 

where: 

EERnorml is the ratio of the EER and the maximum EER at those outdoor and air flow 

conditions 

perchg is the ratio of the installed charge to the correct charge 

Charge Effect on Short Tube Orifice Units The effect of charge on normalized EER was found to 

be only mildly effected by airflow and outdoor temperatures. The following least squares fit to 

the data includes 21 observations and all three regression coefficients are significant at the 95% 

level. 

EERnorml =5.082403 - 4.100056 * perchg + 4.619659 * LN(perchg) 

PG&E TXV Impact Review DRAFT Oct. 23, 2000 Page A-I Proctor Engineering Group, Ltd. 

DRAFT 

APPENDIX A. METHODOLOGY 

Effect on SEER 

The benefit of TXVs on the average SEER of units was determined by examining the published 

performance data for identical matched indoor and outdoor units with orifice and with TXV 

metering devices. 

Effect at field conditions 

The benefits of TXVs in the performance of air conditioners in off design conditions were 

estimated in a three-step process. First, laboratory test data for TXV and short tube orifice 

equipped air conditioners were analyzed and generalized performance maps were developed. 

Second, existing field data on "off-design" conditions were analyzed and distributions of airflow 

and amount of charge were determined. Third, the distributions were applied to the performance 

maps and the resultant differences over the whole population were estimated. 

Laboratory Test Data for Both Metering Devices 

There are a limited number of data sets for air conditioners run at incorrect charge, low airflow, 

and a variety of test conditions. Available data includes Bain et al. 1995, Proctor et al. 1996, and 

Rodriquez et al. May 1995. In all cases the largest compilation of data was used to produce the 

performance equations used in the analysis. In all cases the EER was normalized to the EER at 

correct charge, normal airflow (taken as 400 dm per ton wet coil), and the specified indoor / 

outdoor conditions. 

Charge Effect on TXV Units The effect of charge on normalized EER was found to be only mildly 

effected by airflow and outdoor temperatures. The following least squares fit to the data includes 

27 observations and all three regression coefficients are significant at the 95% level. 

EERnorm1 = 2.289767 -1.294853 * perchg +1.356132 * LN(perchg) 

where: 

EERnorml is the ratio of the EER and the maximum EER at those outdoor and air flow 

conditions 

perchg is the ratio of the installed charge to the correct charge 

Charge Effect on Short Tube Orifice Units The effect of charge on normalized EER was found to 

be only mildly effected by airflow and outdoor temperatures. The following least squares fit to 

the data includes 21 observations and all three regression coefficients are significant at the 95% 

level. 

EERnorml =5.082403 - 4.100056 * perchg + 4.619659 * LN(perchg) 

PG&E TXV Impact Review DRAFT Oct. 23, 2000 Page A-I Proctor Engineering Group, Ltd. 
EE-RM/STD-98-440.- v /a L - L&-

Methodology

where:

EERnorml is the ratio of the EER and the maximum EER at those outdoor and air flow

conditions

perchg is the ratio of the installed charge to the correct charge

Airflow Effect on TXV Units The effect of airflow on normalized EER was found to be only

mildly effected by charge and outdoor temperatures. The following equation has been tentatively

adopted by ASHRAE 152P committee as describing the effect of low airflow on normalized EER

for TXV units.

EERnorm2 = 1.6198 - 0.6198*flowratio + 0.647*LN(flowratio)

where:

EERnorm2 is the ratio of the EER and the maximum EER at those outdoor and charge

conditions

flowratio is the ratio of the actual airflow to 400 cfm per ton

Airflow Effect on Short Tube Orifice Units The effect of airflow on normalized EER was found to

be only mildly effected by charge and outdoor temperatures. The following equation has been

tentatively adopted by ASHRAE 152P committee as describing the effect of low airflow on

normalized EER on these units.

EERnorm2 = 0.65 + 0.35 * flowratio

where:

EERnorm2 is the ratio of the EER and the maximum EER at those outdoor and charge

conditions

flowratio is the ratio of the actual airflow to 400 cfm per ton

Field Data on Charge and Airflow

Charge Distribution The most extensive data on charge are in the CheckMe!® database. This

database is generated from data called into the Proctor Engineering Group offices from

technicians working on units in the field. The CheckMe technicians have the following:

· A day of one-on-two field training including measurements for superheat,

subcooling, and approach.

* Accurate and calibrated tools including a digital electronic refrigerant scale, a two

channel digital thermometer, and refrigerant gauges.

* Immediate access to technical expertise via a toll free number.

· Immediate checks of the readings and their potential accuracy using a computerized

expert system.

* Immediate results of charge tests via the computerized expert system.

PG&E TXV Impact Review DRAFT Oct. 23, 2000 Page A-2 Proctor Engineering Group, Ltd.

EE-RM-STD-98-440 COMMENT 73LL

EE-RM/STD-98-440 .. it 1,5·- L~ 

Methodology 

where: 

EERnorm1 is the ratio of the EER and the maximum EER at those outdoor and air flow 

conditions 

perchg is the ratio of the installed charge to the correct charge 

Airflow Effect on TXV Units The effect of airflow on normalized EER was found to be only 

mildly effected by charge and outdoor temperatures. The following equation has been tentatively 

adopted by ASHRAE 152P committee as describing the effect of low airflow on normalized EER 

for TXV units. 

EERnorm2 = 1.6198 - 0.6198*flowratio + 0.647*LN(flowratio) 

where: 

EERnorm2 is the ratio of the EER and the maximum EER at those outdoor and charge 

conditions 

flowratio is the ratio of the actual airflow to 400 dm per ton 

Airflow Effect on Short Tube Orifice Units The effect of airflow on normalized EER was found to 

be only mildly effected by charge and outdoor temperatures. The following equation has been 

tentatively adopted by ASHRAE 152P committee as describing the effect of low airflow on 

normalized EER on these units. 

EERnorm2 = 0.65 + 0.35 * flowratio 

where: 

EERnorm2 is the ratio of the EER and the maximum EER at those outdoor and charge 

conditions 

flowratio is the ratio of the actual airflow to 400 dm per ton 

Field Data on Charge and Airflow 

Charge Distribution The most extensive data on charge are in the CheckMe!® database. This 

database is generated from data called into the Proctor Engineering Group offices from 

technicians working on units in the field. The CheckMe technicians have the following: 

• A day of one-on-two field training including measurements for superheat, 

subcooling, and approach. 

• Accurate and calibrated tools including a digital electronic refrigerant scale, a two 

channel digital thermometer, and refrigerant gauges. 

• Immediate access to technical expertise via a toll free number. 

• Immediate checks of the readings and their potential accuracy using a computerized 

expert system. 

• Immediate results of charge tests via the computerized expert system. 

PG&E TXV Impact Review DRAFT Oct. 23, 2000 Page A-2 Proctor Engineering Group, Ltd. 

EE-RM/STD-98-440 .. it 1,5·- L~ 

Methodology 

where: 

EERnorm1 is the ratio of the EER and the maximum EER at those outdoor and air flow 

conditions 

perchg is the ratio of the installed charge to the correct charge 

Airflow Effect on TXV Units The effect of airflow on normalized EER was found to be only 

mildly effected by charge and outdoor temperatures. The following equation has been tentatively 

adopted by ASHRAE 152P committee as describing the effect of low airflow on normalized EER 

for TXV units. 

EERnorm2 = 1.6198 - 0.6198*flowratio + 0.647*LN(flowratio) 

where: 

EERnorm2 is the ratio of the EER and the maximum EER at those outdoor and charge 

conditions 

flowratio is the ratio of the actual airflow to 400 dm per ton 

Airflow Effect on Short Tube Orifice Units The effect of airflow on normalized EER was found to 

be only mildly effected by charge and outdoor temperatures. The following equation has been 

tentatively adopted by ASHRAE 152P committee as describing the effect of low airflow on 

normalized EER on these units. 

EERnorm2 = 0.65 + 0.35 * flowratio 

where: 

EERnorm2 is the ratio of the EER and the maximum EER at those outdoor and charge 

conditions 

flowratio is the ratio of the actual airflow to 400 dm per ton 

Field Data on Charge and Airflow 

Charge Distribution The most extensive data on charge are in the CheckMe!® database. This 

database is generated from data called into the Proctor Engineering Group offices from 

technicians working on units in the field. The CheckMe technicians have the following: 

• A day of one-on-two field training including measurements for superheat, 

subcooling, and approach. 

• Accurate and calibrated tools including a digital electronic refrigerant scale, a two 

channel digital thermometer, and refrigerant gauges. 

• Immediate access to technical expertise via a toll free number. 

• Immediate checks of the readings and their potential accuracy using a computerized 

expert system. 

• Immediate results of charge tests via the computerized expert system. 

PG&E TXV Impact Review DRAFT Oct. 23, 2000 Page A-2 Proctor Engineering Group, Ltd. 
EE-RM/STD-98-440 4I ' U-.

Methodology

The initial tests are recorded, and when charge corrections are completed, the amount of

refrigerant weighted in (or out) is reported along with the post repair test results.

The database contains thousands of tests. These data were analyzed for both initial tests and postrepair tests. The initial tests for non-TXV units showed 30% undercharge, 32% overcharge, and

38% correct charge based on actual superheat within 5°F of the target superheat for the

conditions 2. Post-repair tests were used to determine the amount of mischarge for each unit that

was off charge by more than 5%. This produced the distribution of refrigerant charge shown in

Figure 3. The initial test data and the post-repair data show the same percentage of correct charge

as the average in the Neme (Neme et al. 1999) nationwide analysis. This dataset is the most

comprehensive data set available to determine the distribution of refrigerant charge.

Airflow Distribution There is less comprehensive data on the distribution of airflow on

residential air conditioners and heat pumps. The Neme study summarizes fourteen studies that

have some information about airflow across the inside coil. Proctor Engineering was able to

analyze data from six studies to determine the standard deviation of the airflows. The standard

deviations ranged between 16 and 22%. Data from seven studies (some new construction, some

existing construction) showed a range of airflows across the coil averaging between 352 and 270

cfm per ton. For existing construction the data points were 270, 300, and 350 cfm per ton (wet

coil). This analysis is based on a normal distribution with a standard deviation of 80 cfm per ton

and a mean flow of 300 cfm per ton.

2 Units where the test conditions produced a target superheat of less than 5°F were excluded from

the analysis.

PG&E TXV Impact Review DRAFT Oct. 23, 2000 Page A-3 Proctor Engineering Group, Ltd.

EE-RM-STD-98-440 COMMENT 73LL

.... EE-RM/STD-98-440 -tt 13 /' L1--

Methodology 

The initial tests are recorded, and when charge corrections are completed, the amount of 

refrigerant weighted in (or out) is reported along with the post repair test results. 

The database contains thousands of tests. These data were analyzed for both initial tests and postrepair tests. The initial tests for non-TXV units showed 30% undercharge, 32% overcharge, and 

38% correct charge based on actual superheat within 5°F of the target superheat for the 

conditions2 Post-repair tests were used to determine the amount of mischarge for each unit that 

was off charge by more than 5%. This produced the distribution of refrigerant charge shown in 

Figure 3. The initial test data and the post-repair data show the same percentage of correct charge 

as the average in the Neme (Neme et al. 1999) nationwide analysis. This dataset is the most 

comprehensive data set available to determine the distribution of refrigerant charge. 

Airflow Distribution There is less comprehensive data on the distribution of airflow on 

residential air conditioners and heat pumps. The Neme study summarizes fourteen studies that 

have some information about airflow across the inside coil. Proctor Engineering was able to 

analyze data from six studies to determine the standard deviation of the airflows. The standard 

deviations ranged between 16 and 22%. Data from seven studies (some new construction, some 

existing construction) showed a range of airflows across the coil averaging between 352 and 270 

cfm per ton. For existing construction the data points were 270, 300, and 350 cfm per ton (wet 

coil). This analysis is based on a normal distribution with a standard deviation of 80 cfm per ton 

and a mean flow of 300 cfm per ton. 

2 Units where the test conditions produced a target superheat of less than 5°F were excluded from 

the analysis. 

PG&E TXV lmpact Review DRAFT Oct. 23, 2000 Page A-3 Proctor Engineering Group, Ltd. 

.... EE-RM/STD-98-440 -tt 13 /' L1--

Methodology 

The initial tests are recorded, and when charge corrections are completed, the amount of 

refrigerant weighted in (or out) is reported along with the post repair test results. 

The database contains thousands of tests. These data were analyzed for both initial tests and postrepair tests. The initial tests for non-TXV units showed 30% undercharge, 32% overcharge, and 

38% correct charge based on actual superheat within 5°F of the target superheat for the 

conditions2 Post-repair tests were used to determine the amount of mischarge for each unit that 

was off charge by more than 5%. This produced the distribution of refrigerant charge shown in 

Figure 3. The initial test data and the post-repair data show the same percentage of correct charge 

as the average in the Neme (Neme et al. 1999) nationwide analysis. This dataset is the most 

comprehensive data set available to determine the distribution of refrigerant charge. 

Airflow Distribution There is less comprehensive data on the distribution of airflow on 

residential air conditioners and heat pumps. The Neme study summarizes fourteen studies that 

have some information about airflow across the inside coil. Proctor Engineering was able to 

analyze data from six studies to determine the standard deviation of the airflows. The standard 

deviations ranged between 16 and 22%. Data from seven studies (some new construction, some 

existing construction) showed a range of airflows across the coil averaging between 352 and 270 

cfm per ton. For existing construction the data points were 270, 300, and 350 cfm per ton (wet 

coil). This analysis is based on a normal distribution with a standard deviation of 80 cfm per ton 

and a mean flow of 300 cfm per ton. 

2 Units where the test conditions produced a target superheat of less than 5°F were excluded from 

the analysis. 

PG&E TXV lmpact Review DRAFT Oct. 23, 2000 Page A-3 Proctor Engineering Group, Ltd.