a3 D

Public Workshop

on

Residential Furnace and Boiler Venting

May 8, 2002

0

EE-RM/STD-01-350 COMMENT 23D
Public Workshop on Residential Furnace and Boiler Venting

Introduction Outline

Background

Purpose

Discussion Items

Next steps

1

EE-RM/STD-01-350 COMMENT 23D
Public Workshop on Residential Furnace and Boiler Venting

Background

Since FY'2001

, DOE has pursued rulemaking activities to determine if

updated standards for covered residential furnaces , boilers and mobile

home fu rnaces are justified.

-June 19, 2001: notice announced public worksh ire and the availability of

the framework document.

-July 17, 2001: "framework workshop " to explain and discuss the

process , analysis, and issues involved in the rulemaking.

-During the framework workshop, several stakeholders expressed

concerns regarding venting implications of increased minimum

standards.

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EE-RM/STD-01-350 COMMENT 23D
Public Workshop on Residential Furnace and Boiler Venting

Venting Concerns

Several comments were raised in response to the framework document

works hop, wh ich expressed concerns about venting in mid-efficiency

appliances.

"Economic venting options should be considered, which

permit higher efficiency levels without concern for flue gas

condensation, as well as appliance condensation."

"...consider the effect of higher efficiencies on

the equipment's venting capability."

"Increasing the AFUE level beyond 80% will create

additional venting and corrosion durability problems,

articularly in northern markets."

"Furnaces having an 81 -82% ICS AFUE level (82-83%

indoor AFUE) were widely available in the 1980's and

L experienced numerous venting and corrosion problems."

Energy Kinetics

National Propane

Gas Association

Carrier

Corporation

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EE-RM/STD-01-350 COMMENT 23D
Public Workshop on Residential Furnace and Boiler Venting

Venting Concerns (Cont'd)

71

"DOE must recognize that safety must always have priority

over efficiency."

"A significant increase in cost will occur for homeowners

who vent their existing furnaces and water heaters into a

himne

"Our information suggests that levels up to 83% are

technically feasible without significant risk of corrosive

condensation that would threaten conventional furnace

and boiler heat exchangers."

Gas Appliance

Manufacturers

Association

American Council

for an EnergyEfficient Economy

Lennox

Industries

"The corrosive effects of the condensate, in many cases accompanied by the

positive pressure of the combustion products to assure venting, creates a situation in

which no proven safe, cost effective, forced air furnaces are manufactured and

istributed in commerce."

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EE-RM/STD-01-350 COMMENT 23D
Public Workshop on Residential Furnace and Boiler Venting

Background (Cont'd)

To address these concerns, it is necessary to understand:

- The flue gas condensation phenomenon (how it begins to affect the furnace

vent system at higher efficiencies).

- What technology options exist to mitigate the condensation problem.

We reviewed current information on present venting guidelines for

installation of furnaces and boilers, including:

- National Fuel Gas Code (NFGC)

- Test data from various organizations

- Computer simulation models

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EE-RM/STD-01-350 COMMENT 23D
Public Workshop on Residential Furnace and Boiler Venting

Background (Cont'd)

We conducted a preliminary analysis of

- the correlation between steady-state efficiency and AFUE

- the impact of increased efficiency on the NFGC tables

We collected information on technology options to limit concerns

about venting.

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EE-RM/STD-01-350 COMMENT 23D
Public Workshop on Residential Furnace and Boiler Venting

Purpose

Discuss and obtain feedback on:

- Data and results reported by DOE

- Efficiency limits for non-condensing furnaces and boilers, based on the

NFGC and current venting installation practice

- Effect of higher steady-state efficiency on NFGC tables

- Technology options

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EE-RM/STD-01-350 COMMENT 23D
Public Workshop on Residential Furnace and Boiler Venting

Discussion Items

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EE-RM/STD-01-350 COMMENT 23D
Public Workshop on Residential Furnace and Boiler Venting

Next Steps

Incorporate comments (due 6/7/02)

Complete pre-ANOPR analyses (7/02-01/03)

Pu blish

- ANOPR (1/03)

- NOPR (2/04)

- Final Rule (9/04)

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EE-RM/STD-01-350 COMMENT 23D
Public Workshop on Residential Furnace and Boiler Venting

Agenda

10

EE-RM/STD-01-350 COMMENT 23D
Public Workshop on Residential Furnace and Boiler Venting

Venting Code Background

® Since the 1950s, codes have provided requirements for the

i nstallation and operation of gas equipment.

We looked at the National Fuel Gas Code - NFGC

F A-5 /ANSI-Z223.1)

"NFGC is a consensus standard and is intended to promote public

safety by providing requirements for the safe utilization of gas."

® Venting is covered in N FGC

- Chapter 7: Venting of Equipment

- Chapter 10: Sizing of Category I Venting Tables

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EE-RM/STD-01-350 COMMENT 23D
Public Workshop on Residential Furnace and Boiler Venting

Venting Code Background

NFGC Venting Tables have changed over the years as technology

has developed.

National ANSI Z21.47 ANSI Z21.13

Appliance Energy defines adopts

Conservation Act Venting Categories Venting Categories

(NAECA) for Furnaces for Boilers

Tables developed

for natural draft

appliances with

vertical vents and

masonry chimneys

1950 1960 1970 1980 1990

NFGC adopts

tables

for fan-assisted

appliances

2000

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EE-RM/STD-01-350 COMMENT 23D
Public workshop on Residential Furnace and Boiler Venting

Venting Code Background

ANSI Z21.47 and ANSI Z21.13 define four appliance categories, depending

on static pressure in the vent and temperature rise above dewpoint.

CATEGORY I "An appliance that

operates with a non-positive vent

static pressure and with a vent gas

temperature that avoids excessive

condensate production in the vent".

CATEGORY II

Negative

CATEGORY III

CATEGORY IV

Static Pressure Positive

T

High

Temperature Rise

Above Dewpoint

Note : During this workshop we will focus on Category I appliances with

emphasis on condensation issues.

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EE-RM/STD-01-350 COMMENT 23D
Public Workshop on Residential Furnace and Boiler Venting

Venting Code Background

The Vent-11 computer program was developed and used to generate the

NFGC venting tables.

• History of VENT-II

- originally developed in 1983 by Battelle

- updated (1985-1990) to include new technologies and higher-efficiency furnaces

• Validation of VENT-II performed by

- Battelle - single appliance vent systems

- AGA Labs - common vent systems

Validation of VENT-II for venting systems used with Category I appliances

- Type B double-wall vents

- Standard masonry chimneys

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EE-RM/STD-01-350 COMMENT 23D
Public Workshop on Residential Furnace and Boiler Venting

Venting Code Background

Baseline conditions, a set of typical operating parameters and ambient

conditions, were established for Category I furnaces.

Developed After

Consultations and

Review by the Industry

Included a Steady-State

Efficiency Limit of 83%

Venting Tables

Generated

Venting Tables

Adopted into NFGC

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EE-RM/STD-01-350 COMMENT 23D
Public Workshop on Residential Furnace and Boiler Venting

Venting Code Background

T

Venting tables are used in every step of the venting system installation.

Some manufacturer's

installation manuals

include venting tables.

The installer is required

to follow codes and

manufacturers instructions

for furnaces and boilers.

Typically , the building inspector

does not approve the venting Some gas utilities

system unless it meets the do not turn on the gas

applicable venting code. unless the venting system

meets the applicable

venting code.

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EE-RM/STD-01-350 COMMENT 23D
Public Workshop on Residential Furnace and Boiler Venting

Agenda

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EE-RM/STD-01-350 COMMENT 23D
Public Workshop on Residential Furnace and Boiler Venting

Difference Between SSE and AFUE

The difference between Steady State Efficiency (SSE) and Annual Fuel

Utilization Efficiency (AFUE) represents the link between the National Fuel

Gas Code (based on SSE) and the current Federal Standard (based on

AFUE).

Both SSE and AFUE are calculated using the DOE test procedure for residential

furnaces (Appendix N, Subpart B, 10 CFR 430):

- SSE: The difference between 100% and the percentage of heat lost through the

flue (both sensible and latent heat for non-condensing furnaces). Electric energy is

not included.

AFUE: "The ratio of annual output energy to annual input energy which includes

any non-heating-season pilot input loss and does not include electric energy."

We will now focus on gas-fired non-condensing furnaces, which represent the vast

majority of the market. Additional product classes will he descussed in section 5.

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EE-RM/STD-01-350 COMMENT 23D
Public Workshop on Residential Furnace and Boiler Venting

Difference Between SSE and AFUE

There are three ways to calculate the difference between SSE and AFUE

( S - E).

1) From laboratory measurements.

2) From existing directory information.

3) Using a computer simulation model (FURNACE).

there any other data source or way to compute SSE-AFUE?

N ote that AFUE is readily available (i.e. directories of certified appliances), while

SSE is usually not reported.

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EE-RM/STD-01-350 COMMENT 23D
Public Workshop on Residential Furnace and Boiler Venting

Difference Between SSE and AFUE

1) Laboratory measurements

A number of reported laboratory measurements for non-condensing gas-fired

furnaces indicate that:

- SSE-AF U E values range between about 0% and 2.4%

- The average value of this difference is 0.95%

N=24

3

• Do these values reflect

commonly accepted values

of SSE-AFUE?

• Are there other sources to

expand the sample

presented on this chart?

<0.5 0.5-1 1-1.5 1.5-2 2-2.5

SSE-AFUE (%)

Sources: ITS, ADL, ASHRAE

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EE-RM/STD-01-350 COMMENT 23D
Public Workshop on Residential Furnace and Boiler Venting

Difference Between SSE and AFUE

2) Directory information (Methodology)

Apply the formula* SSE-AFUE = (100x QouT' QIN)+ (Jacket Lossesx 1.7) - AFUE

* Derived from the formula for output

capacity in the DOE test procedure

- Input capacity (Q,N), output capacity (QouT) and AFUE values are listed in the directory

- Jacket loss values were obtained from laboratory measurements

Default jacket loss value,

according to DOE test

procedure, is 1%

*Sources: ITS, ADL, ASHRAE, GAMA.

Non-condensing gas-fired furnaces only.

0.0% 0.3% 0.6% 0.9%

Jacket Loss

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EE-RM/STD-01-350 COMMENT 23D
Public Workshop on Residential Furnace and Boiler Venting

Difference Between SSE and AFUE

2) Directory information (Results)

SSE-AFUE values calculated from the GAMA directory show a statistical

distribution with an average of 0.8%.

50% 1

40% H

0

10% H

0%

0 Calculated (GAMA Directory)

Laboratory Measurements

The results are in agreement

with laboratory measurements

(method #1)

<0.5 0.5-1 1-1.5 1.5-2 2-2.5 >2.5

SSE-AFUE (%)

these values reflect commonly accepted values of SSE-AFUE?

Note: A similar analysis has been performed on the CEC directory and results are similar.

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EE-RM/STD-01-350 COMMENT 23D
Public Workshop on Residentia! r urnace and Boiler Venting

Difference Between SSE and AFUE

3) Computer model (FURNACE)

Results indicate that furnaces with tubular heat exchangers have higher SSEAFUE values and that SSE-AFUE decreases at higher AFUE.

3

2.5 -

77.1

Effect of HX Area on (SSE-AFUE)

(Constant Aspect Ratio HX)

78 78.8 79.5 80.7

2

0.5 -

0

3

2.5

1

- 0.5

0

Source: F. Jacob, J. Crisafulli, etc, "Assessment

of Technology for Improving the Efficiency

of Residential Gas Furnaces and Boiler, Vol.!,

GRI-94/0175.2, Sep. 1994

1.5

76 7 78 79 2 80.2 81 6

AFUE, %

Do these values reflect commonly accepted values of SSE-AFUE?

Do this results for tubular FIX adequately represent SSE-AFUE based on

most current furnace technologies?

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EE-RM/STD-01-350 COMMENT 23D
Public Workshop on Residential Furnace and Boiler Venting

Difference Between SSE and AFUE

There are several reasons for the range of cdiculated SSE-AFUE values,

includi :

- Variability among the same product series

- Tubular vs. clam shell heat exchanger

- Round-down of AFUE ratings

I n the field, additional factors might affect actual SSE-AFUE values:

- Gas heat content

- Airflow

- Room temperature

- Test procedure tolerance

® Are there add itional factors to take into consideration?

® Are there any studies which document the impact of the factors

affecting SSE-AFU E?

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EE-RM/STD-01-350 COMMENT 23D
Public Workshop on Residential Furnace and Boiler Venting

Agenda

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EE-RM/STD-01-350 COMMENT 23D
Public workshop on Residential Furnace and Boiler Venting

Additional Venting Issues

=17--

Common ventin g (furnace / water heater) systems might be affected by new

standard levels.

- Impact of new water heater efficiency standard level (effective January 2004):

- It might or might not result in a higher Recovery Efficiency (RE).

- A higher RE could raise additional venting concerns.

Possible changes in furnace venting requirements:

- "Orphaned" water heaters would need to be re-vented.

Are there additional ventin g concerns or opportunities that ap ply

common venting systems?

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EE-RM/STD-01-350 COMMENT 23D
Public Workshop on Residential Furnace and Boiler Venting

Additional Venting Issues

In addition to non-condensing gas-fired furnaces, other product classes are

affected by venting issues.

- Gas-fired boilers

Mobile home furnaces

Oil-fired furnaces and boilers

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EE-RM/STD-01-350 COMMENT 23D
Public workshop on Residential Furnace and Boiler Venting

Additional Venting Issues

as-fire boilers can reach higher AFUE than non-condensing gas-fired

fu rnaces before venting issues arise.

Indoor installation rating

Low return water temperature in the test procedure

Reduced CO concerns

Lower SSE-AFUE than furnaces

- Are there additional factors that

need to be taken into account?

- Are there any boiler simulation

models available?

-1.5 -1 -0.5 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

SSE -AFUE (%)

SSE-AFUE calculated using the GAMA directory.

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EE-RM/STD-01-350 COMMENT 23D
Public Workshop on Residential Furnace and Boiler Venting

Additional Venting Issues

Venting of mobile home furnaces.

Mobile homes are required to be built in compliance with the

Department of Housing and Urban Development 's Manufactured Home

Construction and Safety Standards (MHCSS).

MHCSS requires the complete separation of combustion air and interior air, by

1. Direct vent appliances, or

2. Installation in enclosures sealed from interior air.

® Are there s pecific venting concerns or opportunities that apply to mobile

home furnaces?

® Are there other codes that a pply to this product?

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EE-RM/STD-01-350 COMMENT 23D
Public Workshop on Residential Furnace and Boiler Venting

Additional Venting Issues

Venting oil-fired furnaces and boilers.

- Lower hydrogen content of the fuel

- it-fired appliances use different venting codes including:

- NFPA 31 - Standard for Installation of Oil-Burning Equipment

- NFPA 211 - Standard for Chimneys, Fireplaces, Vents, and

Solid Fuel-Burning Appliances

Are there other specific venting con cerns or opportunities that apply to oilfired furnaces and boilers?

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EE-RM/STD-01-350 COMMENT 23D
Public Workshop on Residential Furnace and Boiler Venting

Agenda

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EE-RM/STD-01-350 COMMENT 23D
Public Workshop on Residential Furnace and Boiler Venting

NFGC Tables at Higher SSE

As steady state efficiency (SSE) increases , the range of available

installations is decreased.

Assume 75 kBtu/hr furnace and 4" Diameter Vent.

Reproduction of Table 10.1: Capacity of Type B Double Wall Gas Vents Directly Connected to a Single Appliance

Vent Lateral

Height Length Min.

Cap.

5

10

10'

15'

20'

5'

10'

15

20

30'

Max.

Cap.

118

113

m 41 I 104

14

29

o 38

z 46

55

11

27

V 35

42

50

69

149

143

133

124

116

183

177

168

158

149

131

Min.

Cap.

35

52

65

30

44

63

78

95

Max.

Cap.

Min.

Cap.

Max.

Cap.

107

102

96

139

134

125

118

109

NA

NA

NA

93

122

NA

NA

NA

NA

NA

NA

NA

167

162

NA

NA

NA

NA

Disclaimer : These tables are provided for discussion purposes only and are not an update of existing NFGC tables.

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EE-RM/STD-01-350 COMMENT 23D
Public Workshop on Residential Furnace and Boiler Venting

Agenda

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EE-RM/STD-01-350 COMMENT 23D
Public Workshop on Residential Furnace and Boiler Venting

Technology Options

ffilw_

For gas furnaces, possible technology options exist in three different

areas to limit concerns about venting.

Decrease

SSE-AFU E difference

Active controls to

allow louver tolerances

' Options that allow the vent

system to handle

SSE's higher than 83%

What technology options

should or s hould not be

considered and why?

- Clam-shell heat exchanger

- Burner box or damper

- Better insulation

- Detection Systems

- Water-activated switches

- CO Detector

-Change appliance operation pattern

- Modulation

- Heat exchanger area control

- Increase excess air

- Remove water from the flue

- Expansion-compression device

- Desiccant

- Enthalpy-desiccant wheel

- Treat the vent

- Vent coating

- Vent pre-heat

- New materials

- Improved vent connector

Require vent code

modification

- Use condensing technology

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EE-RM/STD-01-350 COMMENT 23D