# a3 D

Public Workshop on 

# Residential Furnace and Boiler Venting

M ay 8, 2002

0Public Workshop on Residential Furnace and Boiler Venting 

### Introduction Outline 

## Background Purpose Discussion Items Next steps

1Public Workshop on Residential Furnace and Boiler Venting 

### Background Since F Y '2001 , DOE has pursued rulemaking activities to determine if update d standard s for covered residential furnaces , boilers and mobile h ome f u 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.

2Public 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 applian c es. "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 N ational Propane G as Associatio n Carrier Corporation

3Public 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." 

### G as Appliance M anufactu rers Association A 

## merican Council f 

## or an Energ

# yEfficient Economy Lenno x 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."
4Public Workshop on Residential Furnace and Boiler Venting 

### Background (Cont'd)
To add ress t h ese 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 installatio n of furnaces and boilers, including: - National Fuel Gas Code (NFGC) - Test data from various organizations - Computer simulation models

5Public Workshop on Residential Furnace and Boiler Venting 

### Background (Cont'd)

We co n ducted a preliminary analysis of - the correlation between steady-state efficiency and AFUE - the impact of increased efficiency on the NFGC tables We collecte d information on technology options to limit concerns abo ut v entin g .

6Public Workshop on Residential Furnace and Boiler Venting 

### Purpose

D iscu s s an d 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

7Public Workshop on Residential Furnace and Boiler Venting 

### Discussion Items

8Public Workshop on Residential Furnace and Boiler Venting Next Steps



### In corp orate comments (due 6/7/02) C o mp lete p re-ANOPR analyses (7/02-01/03) P u b li sh - ANOPR (1/03) - NOPR (2/04) - Final Rule (9/04)

9Public Workshop on Residential Furnace and Boiler Venting 

### Agenda

10Public Workshop on Residential Furnace and Boiler Venting Venting Code Background


### ® S ince th e 1950s, codes have provided requirements for the i n stallation and operation of gas equipment. We looke d 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." ® Ve ntin g is covered in N FG C

- Chapter 7: Venting of Equipment - Chapter 10: Sizing of Category I Venting Tables

11Public Workshop on Residential Furnace and Boiler Venting Venting Code Background 

### NFGC Ve nting Tables have changed over the y ears as technology has dev e lope d . 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

12Public workshop on Residential Furnace and Boiler Venting Venting Code Background 

### ANSI Z2 1. 47 and ANSI Z21.13 define four appliance categories, depending on static p ressure in the vent and temperature rise above dewpoint. CATEGORY I "An appliance that operates with a non-positive vent static p ressure 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 : D uring this workshop we will focus on Category I appliances with emphasis on condensation issues.

13Public 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 • Vali d ation 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

14Public Workshop on Residential Furnace and Boiler Venting Venting Code Background 

### B aselin e conditions, a set of typical operating parameters and ambient conditi on s, 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

15Public Workshop on Residential Furnace and Boiler Venting Venting Code Background 

### T Ventin g ta bles 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.
16Public Workshop on Residential Furnace and Boiler Venting 

### Agenda

17Public 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 AF UE). Both SS E 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.

18Public 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) F rom laboratory measurements. 2) From existing directory information. 3) U sin g a co m puter simulation model (FURNACE).



### th ere a ny other data sourc e 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.

19Public 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

20Public Workshop on Residential Furnace and Boiler Venting 

### Difference Between SSE and AFUE 2) Directory information (Methodology) Apply the for mula* 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 los s 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

21Public Workshop on Residential Furnace and Boiler Venting 

### Difference Between SSE and AFUE 2) Directory information ( Results) SSE-A FUE values calculated from the GAMA directory show a statistical distributi o n 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.
22Public 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 SSEA FUE 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?
23Public 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 fi e ld, a d ditional factors might affect actual SSE-AFUE values:

- Gas heat content 

### - Airflow - Room temperature - Test procedure tolerance ® A re th ere a dd itional factors to take into consideration? ® A re th ere any studies which document the impact of the factors affecting SSE -AFU E ?

24Public Workshop on Residential Furnace and Boiler Venting 

### Agenda

25Public workshop on Residential Furnace and Boiler Venting 

### Additional Venting Issues

=17-- 

### C ommon ventin g (furnace / water heater ) systems might be affected by new sta n d ard l evels. - 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. Possi b le changes in furnace venting requirements:

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



### Are th ere a dd itional ventin g concerns or opportunities that ap p ly c ommo n ventin g syste m s?

26Public Workshop on Residential Furnace and Boiler Venting 

### Additional Venting Issues In ad diti on to non-condensing gas-fired furnaces, other product classes are affecte d by ventin g issues. - Gas-fired boilers Mobile home furnaces Oil-fired furnaces and boilers

27Public workshop on Residential Furnace and Boiler Venting 

### Additional Venting Issues as-fire boilers can reach higher AFUE than non-condensing gas-fired fu rn ace s before venting issues arise.

In d oor 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. 28Public Workshop on Residential Furnace and Boiler Venting 

### Additional Venting Issues Ventin g of mo b ile ho m e furnaces.
M ob ile homes are required to be built in compliance with the D epartment 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. D irect vent appliances, or 2. Installation in enclosures sealed from interior air.



### ® A re th ere s pe cific venting concerns or opportunities that apply to m obile h o m e furn ace s ? ® A re t he re other codes that a p ply to this pro d uct?

29Public Workshop on Residential Furnace and Boiler Venting 

### Additional Venting Issues Ven tin g 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



### A re the re ot h er s pe cific ventin g co n cerns or opportunities that apply to oilfire d furna ces and boilers?

30Public Workshop on Residential Furnace and Boiler Venting 

### Agenda

31Public Workshop on Residential Furnace and Boiler Venting 

### NFGC Tables at Higher SSE As stea dy state efficiency ( SSE) increases , the range of available installati o ns 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. 32Public Workshop on Residential Furnace and Boiler Venting 

### Agenda

33Public Workshop on Residential Furnace and Boiler Venting 

### Technology Options
ffilw_ 

### F or gas fu rnaces, 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%



### Wh at te c hno lo gy o ptions s h o u l d o r s h oul d not be c o nsi de red a n d w hy ? - 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
34