Gas Interchangeability Testing Report

Report Prepared for:

Air Conditioning, Heating and Refrigeration Institute(AHRI)

American Gas Association (A.G.A.)Association of Home Appliance Manufactures (AHAM)

November 12, 2009Date of Testing: February 2008 to April 2009

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Program Objective

The objective of this program was to investigate the operation of current designs of gasappliances when tested on four (4) different test gases representing possible gas mixturesthat may be utilized in the United States in coming years. An advisory committeeassembled by GAMA/AHRI and funded through various industry groups did theselection of gas composition. The four tests gases are presented as variations of theirWobbe Index (See the Appendix for a definition of Wobbe Index and its significance toappliance safety).

The test program detailed in this report used 78 new (from stock), current productionproducts and technologies. The program did not review products that are no longerproduced, often referred to as legacy products, but rather focused on products currently inproduction and available to the consumer.

A list of products by sample number only (manufacturers’ names omitted) is contained inthe tables at the end of this report. Since the manufacturers supplied the samples withoutcost to the program, it is believed that anonymity of the test results is appropriate.

The testing was conducted in a manner that represents what would be required for thatproduct to meet the national safety and performance tests that are outlined in the variousANSI standards that govern the design, testing and production of those products. Theappliance industry has 80+ years of evaluating products per the protocols outlined inthese standards and believes that compliance with these test procedures insures theupmost safety to the consumer over the life of the product when installed, maintained andserviced per the manufacturer’s instructions.

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Test Results

Contained at the end of this report is a section labeled “Tables” and those tables containthe consolidated results in a condensed format along with a list of products submitted (bysample number only – manufacturers’ names withheld). The actual data for each sampletested has been provided to the sponsors and is not included herein due to its voluminousnature (approx. 430 pages)

When reviewing the individual data sheets, please be advised that any value of CO(carbon monoxide) recorded as “1050” ppm means that the upper CO range of theinstrument has been exceeded. It was not determined how far above 1050 ppm the actualvalue was, but the 1050 value was used for computational purposes in determining theminimum Air Free CO value that the results could have been, hence there are timeswhere the CO values may be recorded (air free) on the data sheets as 1200, 2000, or moreppm. This is just the result of the mathematics of using 1050 ppm (maximum range ofinstrument) inserted into the air free calculation. Hence, the value is at least the numbershown and may be much higher. Most likely any recorded CO air free value over 1100ppm in the tables (attached) were generated because the measured CO was above 1050ppm1.

Some comments are in order when reviewing the consolidated data sheets (Tables).

The individual sample data is presented with the lowest Wobbe Index gas (E)shown on the top row of data and the highest Wobbe Index gas (D) is shown asthe fifth row of data, with test gas A in the middle or 3d row.

The column labeled “Measured Input” is the measured input after any orifice orpressure change adjustments were made to bring the appliance withinspecifications as explained below.

The column labeled “% of Data Plate Input” is the “Measured Input” columndivided by the Data Plate Input. It is the data in the third row for gas “A” thatshould be within the specifications of tolerance detailed in the appropriatestandard and as explained below in the test procedure write up.

The column labeled “% of Test Gas A Input” reflects the change in input thatoccurred as the various Wobbe Index gas are used. By definition Test Gas “A”will always be 100.0%. In some cases the values do not follow the expectedincrease in input. This may have been human error in recording the results. Butsome of the reason may be that with some appliance designs, on a “hotter” gassuch as gas D, there may have been conditions in which the actual heat on themanifold pipe or orifice increased to a point where the gas within the appliance

1 To make that determination: Multiply the stated value in the table by 12.2% and then divide the resultantvalue by the recorded CO2. This will give the reader the base CO value used for the calculation.

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piping system became “hot”. Such a condition causes a density change in the gasbefore it travels through the flow control orifices, with the result that themeasured gas input is reduced. It is expected that there will always be somedensity change of the gas in the appliance plumbing as the unit runs longer, andfor this reason the appliance standards detail when the input rate is to be recorded.Ranges, water heaters and some boilers are very prone to rate reduction issuesover elapsed time from a cold start. It was also noted that gas pressure regulatorsettings were changing by just changing the gas selection. This may be due tochanges in mass flow through the regulators on products that are near the limitcapacity of the regulator design.

The word “Fail” is utilized in the test data as a way of stating the unit is not incompliance with the test criteria. This only means that the unit has exceeded thepermissible values for some test parameter (CO, NOx, temperature, time forignition, etc.) as detailed in the appropriate ANSI Z21 standard for that producttype. It should not be taken in a negative context but only in the sense that mostgas appliance testing has to meet a pass/fail criteria and this test program isutilizing these criteria to assist in the decision process.

Of the 79 products tested that worked satisfactorily on Test Gas “A”, 40 unitsencountered some form of non-compliance on the remaining 4 test gases (B, C, D, & E).Or stated another way, within the scope of this limited testing, 39 units successfully metthe established pass/fail criteria on all gas mixtures. Yet, even within those 39 units thatwere under the established CO generation limits, many exhibited increased COgeneration as the Wobbe Index increased.

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Test Protocols – General

The following is to assist the reader in understanding some of the tests that wereperformed on the various test appliances and what some of the notes and comments in thepresented data may be referring to. The discussions in this section are more generic innature and specific deviations (by product type) from this general discussion can befound in each section detailing specific appliances.

The actual tests procedures for conducting the tests noted below are found in theappropriate ANSI standard. For instance, gas furnaces are tested to ANSI Z21.47, boilersare tested per ANSI Z21.13, domestic water heaters to Z21.10.1, etc. See the Appendixfor a complete list of the appropriate standards and their full titles.

The normal test sequence for gas appliances as tested under this program was:

1. Rate the product to match the data plate input (Btu/Hr) in accordance with theprocedures outlined in the appropriate ANSI standard for that appliance typeusing test gas A. In all cases that input had to be within either ±2% or ±5%depending upon product type.

2. Run ignition evaluation under a series of different adverse conditions to prove thereliability of safe ignition of the gas over the expected life of the product

3. Run Burner Operating Characteristics (B.O.C.) to prove the continued safe andsatisfactory operation of the burners under a series of adverse conditions thatproves the reliability of the product for the consumer

4. Evaluation of Carbon Monoxide (CO) emissions from the appliance under a seriesof conditions that proves the safety of the product under conditions of variabilitythat are historically considered to provide safe operation of gas appliance over thelife of the product.

5. Conduct NOx 2 emission testing for products subject to state or regional NOxregulations (furnaces, boilers, water heaters) or where specified, by the ANSIstandard such as for vent free heaters.

6. On some furnaces, additional data was accumulated concerning metal heatexchanger temperatures, but the test procedure utilized does not represent the full,and very in depth, manner of looking at possible heat exchanger fatigue asdetailed in the ANSI Z21.47 standard. The goal of this program was to look attrends rather than absolute values.

A more in depth discussion of the appropriate test procedure is found in discussionsbelow.

Procedures for Placing the Appliance “On Rate”

The appliance rate (input) was measured upon receipt of the appliance to verify that itwas within the specifications detailed in the appropriate ANSI standard. As an example,

2 NOx = Nitrous oxide + Nitrogen dioxide or NOx = NO + NO2

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a furnace must be within ± 2% of the input as stated on the data plate as measured 15minutes after starting the appliance from a cold start (room temperature).

To achieve those tolerances a slight variance of the manifold pressure is permitted (± 0.3”w.c.) from the nominal manifold pressure that is also stated on the data plate. If varyingthe manifold pressure will not meet the ± 2% value, then the “tester” must install neworifices that achieve this requirement. For safety reasons the testers goal is to be between0.0 and + 2% rather than drift into the - 2% value. Basically, this is because the higherthe input during testing, the harder it is to meet the other safety requirements laid out inthe ANSI standard. By striving for the 0 to + 2% value, additional safety is ensured forthe end user over the life of the product.

For this test program, a very defined gas (Test Gas “A”) was used that has a WobbeIndex that is representative of the average Wobbe Index of natural gas in the U.S.

Of some historical interest, it should also be noted that this gas also mimics the traditionaltest gas available in Cleveland, Ohio, and in the Appendix is a sample analysis withtypical constituents of Cleveland pipeline gas. The significance of this location is that inthe late 1920’s, Cleveland was the location where the gas utilities of the United States setup and funded the primary American Gas Association (A.G.A.) Testing Laboratory forgas appliance testing. Until the mid 1990’s this facility traditionally performed the vastmajority of the household and light duty commercial gas appliance testing/listingprograms.

Along with Test Gas “A” (Wobbe= 1345), four additional gases were used for testinginput, ignition, BOC and combustions; the remaining four gases are designatedalphabetically:

B Gas Wobbe = 1405 or 4.4% higher than Gas AC Gas Wobbe = 1209 or 4.09% lower than Gas AD Gas Wobbe = 1430 or 6.32% higher than Gas AE Gas Wobbe = 1230 or 8.55% lower than Gas A

Each gas has its own distinct composition and Wobbe Index.. Please review the table inthe Appendix for gas composition, heating value and Wobbe Indexes.

As the other test gases (B through E) are tested, no adjustment of rate or manifoldpressure was made.

Testing for Flue Product Emissions

The major testing issue/concept that relates to safety of gas appliances concerns thecarbon monoxide emissions in the flue gases. Most of the ANSI standards require acarbon monoxide amount lower than 400 ppm (0.04%) Air-Free CO emissions with theexception of cooking products which permit 800 ppm (0.08%)Air-Free and unventedheating products which only permit 200 ppm (0.02%) Air-Free. (For a discussion of “AirFree” measurement procedures and their significance see the Appendix)

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The CO and CO2 emissions were measured using Siemens Ultramat model 23 Non-Dispersive Infra Red (NDIR) gas analyzers which were calibrated daily using NISTtraceable calibration gases. The carbon dioxide (CO2) and carbon monoxide (CO)effluent from the appliances were pumped from the appliance, through a conditioningsystem (to remove water vapor) and then into the analyzers. In the case of gas ranges, asiphon bottle technique was used for some top burner designs as a means of “averaging”the value of the effluent.

NOx emission testing, when the protocol called for it, was measured using either aThermal Electron Corp. 10A or 42C chemiluminescent analyzer and was calibrated dailyusing EPA protocol gases containing known quantities of NO and NOx.

Emission compounds such as NOx and CO will be presented as ppm (parts per million)as these are the types of values the instruments read in and the values most often seen inpublications. The ANSI standards most often give the allowable values as %. To convertfrom ppm to % simply shift the decimal point 4 digits to the left. Hence, 400 ppmbecomes 0.04%.

Test Apparatus

All appliances were set up and connected to one of three test stations designedspecifically for this test program. The stations had six gases piped directly to solenoidvalves used for switching from five specific gas mixes: A, B, C, D, E and “local citygas”. The term “local city gas” refers to the local gas supply provided by Dominion EastOhio Gas Company. The temporary use of local city gas is done to reduce theconsumption of test gases during initial start up and warm up procedures along withextended run time situations.

Because the test gas mixtures had up to 8 components they were expensive to haveblended and analyzed. Therefore, the use of this test apparatus allowed for conservationof the “expensive” gases by not using it for heating up the appliance for extended testruns as called for under some conditions of test in the ANSI procedures. By using shortgas lines from the test cart to the appliance being tested and preset pressure regulators toquickly switch from normal pressure to reduced and then increased inlet pressureconditions, conservation of the expensive test gases was successful. Sufficient time wasalways allowed when switching from “city gas” to the test gas to make sure the appliancewas in fact operating on the test gas and not some blend of test gas and city gas. In somecases there were marked differences in flame appearance and noise levels as the gascompositions changed. Hence, it became easy to tell when the fuel mixtures werechanging in the gas lines to the appliance.

The input rate was computed using calibrated gas meters specially ordered for thisprogram that had 7 test point accuracy curves provided. All calculations were computedfor STP (Standard Temperature and Pressure) conditions by measuring the actualbarometric pressure in the laboratory and the actual temperature of the gas in the gas

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meter along with the gas pressure in the gas meter. At the completion of the testprogram, the gas meters were again sent out for calibration/verification and found to havenot drifted in their accuracy from when the program began. Hence, the accuracy of thereadings of gas input from the beginning of the test program to the end remainedunchanged.

With rate established using Test Gas “A”, ANSI standard combustion tests wereperformed on each of the test gases. The same manifold pressures established on “A” gas,were repeated on the remaining four gases (B, C, D and E). Rates, as expected, increasedand decreased with the changes in Wobbe Indexes.

This report outline is alphabetical by product type and listed below are some of the testsperformed on the boilers. Therefore, a more in depth description of the basic set up andperformed tests will be given to boilers. All of the appliances tested were set up andtested to ANSI test standards written for the respective appliance.

Actual Tests Performed

Combustion Tests

As interpreted from the ANSI Standards, throughout the tests outlined below, anappliance shall not produce a concentration of carbon monoxide in excess of 0.04 percent(the same as 400 ppm) in an air-free sample of the flue gases when tested in anatmosphere having approximately a normal oxygen supply.

Normal Combustion Test: With the appliance at equilibrium with the roomtemperature, it is then placed in operation. After three minutes of operation thecombustion and rate are checked for compliance with the standard. Note that therate is also recorded at 3 minutes but that value may be different than thatrecorded at the 15 minute period of time as defined in the standard for taking rate.

Reduced Inlet Pressure Combustion Test: After the above sample is recorded, theinlet pressure is reduced to mimic low main line pressures that may occur in the“field” during peak gas usages. For “natural gas” appliances the pressure isreduced to 3.5” w.c. pressure or exactly half of the normal natural gas inlet testpressure. After five minutes of operation (from the cold start) the emission data isrecorded.

Overfire or Increased Rate Combustion Test: This condition increases rate byraising the manifold pressure until an increased rate is achieved. The amount ofincrease required varies with the type of appliance being evaluated. It can be ashigh 112% for a gas furnace or as low 106.25% for a boiler. Increasing the inputrate simulates a spike in heating value/Wobbe Index, which may happen when gassupplies fluctuate from a supplier’s well. It is also intended to mimic localatmospheric changes due to weather fronts, to compensate for productionvariations, installation variations, and varying field maintenance schedules. Afterfifteen minutes of operation from the initial start of combustion testing, emissionlevels are recorded for CO2 and CO.

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After conducting the overfire test noted above, the product is returned to normalmanifold pressure (normal input rate) and voltage variation testing is performed.

Reduced Voltage Combustion Test: Check for operation at minimum line voltagebased on 85% of the rating plate voltage. This can be critical on appliances withinduced draft or power burners where the fan speed slows down at lower voltages.This fan speed reduction in turn has a direct effect on combustion emissions (CO,etc.). The evaluation is done with the appliance operating at “normal” input asopposed to low inlet pressure or an “overfire” condition.

Burner Operating Characteristics

Burners shall not flashback when the gas is turned on and off, per the Boiler ANSIZ21.13 standard section(s) 2.6.1 a. through f. The testing covers burner operation withcold and hot appliance conditions along with:

a. At burner adjustments and inlet pressures specified in section 2.3: appliance inletpressures: 3.5”, 7” & 10.5” water column.

Note: In North America the standard delivery pressure to homes andbusinesses is considered to be 7” w.c. pressure (1/4 psi or 4 oz.) and 3.5”and 10.5” w.c. are considered temporary pressure variations that mayoccur due to high gas demand issues caused by cold weather (lowpressure) or lack of demand in the system during warm weather causinghigh pressures (10.5” w.c.). The demand issues may be in the localutilities pipeline or may be in the internal piping of the actual building orresidence.

b. At 1/3 of the normal rate by closing down a manual gas valve ahead of theappliance. This test is only utilized in the furnace standard.

Note: This condition is viewed for some product types as a burnerflexibility test such that under any adverse condition of low pressure to theappliance due to plumping issues within the building, etc, the burner willburner properly and not flashback, i.e., burner inside the burner.

c. At normal inlet with voltage varied to 85% and 110% of nameplate voltage.d. 87% of the minimum low fire input rate when equipped with a step-rate control.e. 87% of the minimum input when equipped with a modulating control.

Blocked Vent System

Sections: 2.22, 2.23 and 2.24 within the ANSI furnace standard covers potential blockageof the vent system. The standards for all appliances that are equipped with fan assistedhave similar combustion requirements, i.e., that the blockage of the exhaust vent pipemust shut the appliance off (may be done by a pressure switch or other type sensor)

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before the CO emissions, on an air free basis, exceed an allowable amount as establishedin the ANSI standards. In the case of most heating equipment such as boilers, themaximum permissible air free CO value is 400 ppm (0.04%).

On the consolidated test sheets, no results are shown for reduced inlet pressure, but therewere two products that failed this test that could be attributed to Wobbe Index issues (SeeVent Free and Water Heater Test Results). Those products have special notationsconcerning the issue.

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Specific Test Programs by Product Type

The product types are listed in alphabetical order.

In the discussions below some general test results are give for each product type but thereader is cautioned to refer to the test results shown in the appendix for more detailed andin depth results.

Boilers

Six (6) boiler manufacturers provided 13 samples of low pressure residential/commercialboilers for inclusion in this test program. The boilers were limited to a maximum 300,000Btu/Hr input rating in order to conserve on gas consumption. Since all the products testedwere “scalable” products, testing smaller input versions does not change the results thatone would expect on the scaled up (or down) versions of the same product family. Thebreakdown by type of the thirteen boilers are:

2 Multiple input rates (non-condensing)4 Natural draft with draft hoods (non-condensing),2 Induced combustion system (non-condensing)1 Flame retention power burner (non-condensing)4 High efficiency (90%+ efficient) condensing with modulation

Using a tempered water reservoir (1,500 gallons), water throughput was maintained at therequired test temperature enabling the appliances to run for the extended amount of timerequired for testing. Appliances were installed in accordance with the respectivemanufacturer’s instructions with thermocouples monitoring the inlet and outlet watertemperatures; water flow was then adjusted to maintain the rise range.

Natural draft boilers were set up with a minimum vent pipe (stack) attached to the draftdiverter as detailed in the Z21.13 standard. Fan assisted combustion systems were testedwith the minimum vent length for sidewall venting as detailed in the manufacturer’sinstructions/listing.

Observations and Comments:Boilers equipped with a “Natural Draft” vent system showed an increase in CO emissionsfrom higher Wobbe Index gases but only one saw a marked increase (sample #50). Asexpected all units saw an increase in input by as much as 7% increase over normal dataplate input rate. All “Natural Draft” combustion samples passed allowable Air Free COemissions along with passing the Burner Operating Characteristics (B.O.C.) part of theprogram.

Two boilers sampled using “Induced Draft” vent systems produced overfire combustionsamples with Air Free CO levels above 400 ppm (0.04%) while operating on tests gasses“B” and “D”.

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“Normal” input rate increases over data plate rates on “D” gas were up to 7 percentabove the normal input on “A” gas.

Further operational testing revealed no other failures in Ignition or Burner OperatingCharacteristics.

Two multiple input rate boilers (two stage) tested produced notable failures, including aB.O.C. failure operating on the lowest Wobbe Index (sample #16), “No Ignition” atreduced inlet pressure with cold (room ambient) and hot conditions on “E” Gas.

The same boiler sample (#16) failed reduced inlet test pressure on all gases with thelowest Wobbe Index gas giving the highest Air Free CO and the highest Wobbe Indexgas resulting in the least Air Free CO (but still exceeded 400 ppm). But the same samplepassed all overfire CO testing.

Four high efficiency “condensing” boilers were tested with input rates between 105,000Btu/Hr and 155,000 Btu/Hr. Two samples failed “D” gas increased rate emission testwith over 400 ppm CO air free. One sample would not operate at the 106% increasedrate because the system would not adjust up to that required overfire condition using thethrottle screw adjustment and when run to its maximum input (less than 106.25%overfire), it generated high levels of combustion noise and generated more than 400 ppmCO air free.

It should be noted that the testing of the high efficiency (condensing) modulating boilersinvolved the setting of a throttle screw rather than manifold pressure. The result is thatthe increase in input did not track well with changes in Wobbe Index because the actualgas flow is being manipulated for every test gas. Hence, the testing staff may not havegotten the throttle setting back to exactly the correct setting (CO2 was used as the“marker”) before advancing to the next test gas in the sequence. 3

NOxNOX emissions were recorded every time CO2 and CO samples were taken. This extradata aids in the determination of what effects the higher Wobbe and heating valueindexes have on emissions during the operation on different gases. The results of theseNOx values should not be confused with the procedures used for California or other stateair quality testing. The NOx data presented here has been presented in a “ppm” format.For state EPA testing (California, etc.), the data is normalized based upon applianceefficiency data (either reported or actually generated during full NOx EPA testing) and

3 Testing Note: In hindsight and for any future “tester”, for any combustion systememploying throttle screws and zero governors (commonly referred to as constant gas/airratio controls or tracking controls), one should test each individual test condition (rate,normal combustion, reduced inlet pressure, combustion, blocked outlet and inlet, etc.)and then step through each gas (A through E). Thus, leaving the overfire test to be thelast test conducted. In this manner one can avoid changing the throttle screw multipletimes and loosing some continuity of data/settings.

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presented in a weight of effluent per amount of energy consumed (nanograms per jouleor Ng/J). This procedure requires a more in depth test procedure than was conducted forthis program.

For boilers the data has been presented at 3% oxygen level (a typical reporting techniquefor boilers) but when presented for all other products it has been presented in “ppm” on asimple air free basis.

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Dryers

Four (4) manufacturers contributed a total of nine (9) residential gas dryers to thisproject. All of these were tested to ANSI Z21.5.1 standard for Type 1 Residential Dryers.

Test consoles remain primarily the same as used for the boiler testing. Additional dataacquisition capabilities were incorporated into the Siemens NDIR Combustion Analyzerto log emissions in 5-second intervals during the blocked outlet portion of the tests thatsimulates lint blockage in the vent. While running blocked exhaust cycle combustiontesting, results were recorded into Excel Spreadsheets for post run analysis of COemissions. The cyclic nature of the test (cycling on temperature or other safety typecontrols) and the time averaging method of the CO calculations called for by thestandard, are better conducted consistently if the data is computed using a graphical postrun analysis process such as a spreadsheet program.

Notable Differences in Test Procedures from the Generic Information Given Above

All tests were performed using cotton fabric test cloths as a dryer load material (seesection 2.1.6 of Z21.5.1) with the correct dimensions and thread counts. Dryer cloth testload weights were based on each manufacturers stated dryer capacity.

Overfire (Section 2.3.3) Gas dryer overfire rates are different from the boiler 106.25 %and furnace 112% overfire combustion test. Dryers require 30% increase in manifoldpressure above normal operating pressures rather than an absolute increase in input.Hence, the dryer overfire conditions are driven by pressure rather than input as found inalmost all other appliance types.

Dryer Combustion tests were conducted in accordance with exhaust test conditionsindicated in Table III, Dryer Exhaust Duct Connection for Performance tests section 2.1.5of the standard.

Because dryer vents are very prone to blockage by lint buildup, a Blocked Vent test wasconducted. Section 2.4.5 states that after 5,000 BTU of gas have been consumed, eachdryer shall be cycled for five on/off cycles while the vent system is restricted or blocked.This blockage can be up to 100% of the outlet exhaust if need be. During the entireblocked vent system testing, the combustion/emissions data is continuously monitoredand recorded on Excel spreadsheets to facilitate the necessary calculations that are basedon a time averaging process. Every appliance has its own data file with graphs generatedfrom the cyclic blocked exhaust tests on each of the test gases. Only the outcome of thedata has been presented in the attached data sheets. Analyzing the cycling data containedin the Excel spreadsheets generated this information.

Observations and Comments:Dryer inputs and capacities varied on the nine sample appliances, inputs rates rangedfrom 10,500 Btu/hr (apartment style washer/dryer combination) up to 22,000 Btu/hr withdrum capacities from 3.4 cubic foot (apartment unit) to 7 cubic foot per load. The load

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weight of dampened ANSI test cloths ranges from 9 to19 pounds depending upon modeltested.

Gas dryers are designed to operate with large amounts of excess air in the combustionchamber to keep from burning the clothes; this results in lower amounts of CO2 in theexhaust emission sample. This plays a crucial role in calculating the Air Free COamounts because the low levels of CO2 in the denominator of the “air free” formulashown in the Appendix equal very high dilution factor multipliers when computing theair free CO levels.

Every dryer passed Burner Operating Characteristics (B.O.C.). While operating on “D”gas, one sample produced AFCO levels over 400 ppm.

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Furnaces

Seven (7) manufacturers provided a total of 15 furnaces for testing. The appliancebreakdown by furnace types were:

2 Outdoor (non-condensing)5 80%+ non-condensing8 90%+ condensing

Furnace products were set up using ductwork supplied by the manufacturers or ductworkfrom Gas Consultants, Inc. in-house inventory. Units were run at ANSI standard externalstatic pressures on city gas during the initial start up and air throughput adjustmentperiod. If the unit as received did not meet the ANSI Z21.47 rate requirement (see section2.5.4) of ± 2 %, either the manifold pressure was changed from nominal data plate valueby no more than ± 0.3”, or by re-orificing (or both).

Appliances were operated at prescribe data plate input rate and voltage on “A” gas forbaseline input and baseline combustion results. The pressures at the gas meter, applianceinlet and manifold were recorded. These pressures were maintained when operating theappliance on the remaining test gases during: normal inlet, reduced inlet, overfire(112%), reduced voltage, minimum rate, blocked inlet / blocked flue and steady state.For the 1/3 flashback testing a special bypass gas loop equipped with a precision flowcontrol valve was used so that once the condition was set on gas “A” the same settingwould be maintained throughout the rest of the gas testing (B, C, D and E gases).

In a simplified description of the test, it should be noted that if a furnace does notlight during conduction of the 1/3 rate test and shuts down within the flameproving period of time (lockout), the input is increased until successful ignition isobtained. Only a burner that flashes back (burns inside the burner head/mixer)under this condition is deemed to be non-compliant with the clause.

Since this program was to focus on changes between gas compositions, only themanufacturer’s specified minimum vent length was used on Category IV products(condensing) for the conduction of all tests noted above. It was felt that any trends inappliance performance would be recognizable when conducting the test on minimumvent length only, rather than both the minimum and maximum vent lengths traditionallyused for safety product evaluation. Had maximum vent lengths been used for testingthere may have been additional CO issues on more furnace samples (the same commentis applicable to any of the power vented products tested under this program). ForCategory I listed products the ANSI Z21.47 “spillage stack” was utilized for testing (seesection 2.2.3 of ANSI Z21.47 and for Category II, III or IV products, per section 2.2.5of Z21.47)

Minimum Vent pertains to what the manufacturer states in their installation instructionsas the shortest allowable vent length for safe operation of the appliance after installation.

Test Performed (See ANSI Z21.47 Gas Fired Central Furnaces)

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Rate (section 2.5)Rise (section 2.6)Burner Operating Characteristics (BOC) (section 2.9)Combustions (section 2.8)Blocked Inlet/Outlet (section 2.2 & 4.4.6)Heat exchanger Temperatures (section 2.17)

(If the appliance manufacturer installed thermocouples.)

Comments about Specific Tests on FurnacesNOxNOX emissions were recorded every time CO2 and CO samples were taken. This extradata aids in the determination of what effects the higher Wobbe and heating valueindexes have on emissions during the operation on different gases. The results of theseNOx values should not be confused with the procedures used for California or other stateair quality testing. The NOx data presented here has been presented in a “ppm” formatand was not intended to be a substitution for the full EPA method required by some stateagencies which is far more complex than the simple procedure utilized in this program.

Steady State EfficiencySteady state efficiency was recorded on the combustion data sheets for each gas. Thisdata was taken during steady state operation and was calculated using a “Flue Loss”program. For condensing furnaces condensate was collected during a clocked time andweighed for use in the efficiency calculations. These results recorded were steady statevalues and should not be compared to AFUE results or expectations.

112% OverfireThe increased manifold pressure required for 112% data plate input on “A” Gasdetermines the increased manifold pressure on the remaining test gases regardless of rateobtained. As an example, if 4.3” was required on “A” Gas to achieve the 112% overfirecondition, this same manifold pressure was used on the remaining test gases, therefore onhigh Wobbe Index gases, overfire was above 112% of the data plate input. This was adecision made early on in the process of how testing would be conducted on all products.

Burner Operating Characteristics (BOC)There where two units that had ignition issues during the 1/3 turn down procedure (fail toignite and then go into lockout) while running the lowest Wobbe gases, but they wouldlight at a higher manifold rate and continue to operate on the slightly higher pressure.

There were no noisy burners or combustion noise at ignition, and aside from two separatemanufacturers having the 1/3 turn down issues (on gases C and E only ) that requiredresetting of the 1/3 rate condition from that used on gas A, no other B.O.C. problemswere encountered on any of the gases.

CombustionsCombustion failures were found at overfire conditions on the higher Wobbe/heatingvalue gases. With the higher Wobbe indexes; four furnaces failed overfire (112%).

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Vent SystemsUnder vent testing, blocked inlet and outlet were another area where higher Wobbe Indexgas has brought about some failures. Four furnaces encountered combustion failures on“B” or “D”, high Wobbe gases, with blocked Inlet / Outlets at factory switch settings. Itwas decided during initial discussions with GAMA (later AHRI) that the pressure switchwould be left in the operational circuit, and the CO would be recorded at the pressureswitch trip point.

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Ranges & Cooktops, Domestic

Five (5) range manufacturers contributed a total of nine (9) products for testing. Thefollowing types of cooking appliances were tested to Z21.1:

1 Built in Oven1 30” Commercial grade free standing range2 48” Commercial grade free standing ranges2 30” freestanding ranges3 Drop in Cooktops (Top Section Only)

Notable Differences in Test Procedures from the Generic Information Given AboveSpecial test pots are utilized for combustion testing of open top burners and are detailedin the Z21.1 standard. In addition to these pots; specifically detailed cast iron griddleplates are required for the increased rate overfire tests. (See the Appendix forphotographs of the 7½” test pots and 9 ½” griddle plates used during testing)

Open top broiler sections require the use of a sheet metal plate to cover 75% of the gridarea for combustion tests, the shape of the cover shall allow an equal uncovered widtharound the perimeter of the grill section.

Sampling hood requirement: A four-sided hood plus top cover with adjustable legs andadjustable sample hole opening in the center of the panel is required for range top/cooktop combustion samples.

Appliances with ovens and broilers are to be set to operate at the maximum temperaturewhen testing the cook top sections. All burners below cooktops (such as ovens) or at thesame height of the burner under test (such as the other open top burners) shall be inoperation when testing the emissions from those burners.

Combustion Tests:The maximum permissible CO air free is 800 ppm (0.08%) for cooking appliances. Theoperational time before sampling for emissions for any given section of the range isdetailed in the standard but generally sampling starts at 5 minutes from a cold start. Allopen top burners are sampled as one combined sample but all other top burners (broilersand/or griddles) are sampled individually as are the ovens and enclosed broilers.Additionally, the open top burners (without ovens in operation) are to be tested at 112%overfire with specific cast iron griddle plates placed on two adjacent open top burners.All other top section burners shall also be in operation.

Burner Operating Characteristics:Burner ignition shall occur within 4 seconds of gas at the ports without undue noise,lifting, blowing or any undesirable operation. Ovens shall light at room temperature andat hot conditions without flame entering the oven cavity. Appliances using electricignition systems (hot surface or direct spark) must operate at 85% and 110% of theirrated voltage. At least five successive ignition attempts shall be made on each top surface

20

cooking section with the lower sections (ovens) in operation and the unit both at roomtemperature and hot.

Observations and Comments:All household-cooking products passed ignition testing along with the B.O.C. portion ofthe program.

When the CO testing was conducted utilizing the “standard” combustion test load(special 7.5” diameter test pots) with the lower ovens in operation, all ranges passedcombustion (AFCO). As noted above, an additional test is required in the ANSI Z21.1standard for open top burners in which 9.5” griddle plates are placed over two adjacentopen top burners, then all top burners are placed in operation at overfire condition but theovens are not operated and the AFCO is recorded. Two appliances (ranges) failed thisopen top burner “griddle” overfire AFCO emissions test.

21

Room Heaters: Vent Free Style Heaters

Two manufacturers supplied a total of 3 vent free heaters (formerly referred to asunvented heaters). Two heaters were blue flame burners and one utilized a ceramicinfrared burner. These products were tested to the ANSI Z21.11.2 standard.

Combustion Tests:The over-fire increases to 123% compared to 112% or 106.25% for other types of eappliances, reduced inlet pressure is 50% of normal supply pressure (same as otherappliances) along with allowable Air Free CO limit lowered to 200 ppm maximum.

Another requirement under Z21.11.2 (section 2.4.4) is that the NO2 (nitrogen dioxide)when measured on an air free basis must not be greater than 20 ppm. Determination ofNO2 requires the measurement of NO and NOx.

NO and NOx emission samples are secured through the use of a stainless steel samplehood placed above the appliance as described in section 2.4.6.

Burner Operating Characteristics:Section 2.5, flashback at reduced inputs along with carry-over at both hot and cold testconditions.

Observations and Comments:The only notable failure was on the ceramic infra red style heater which failedcombustion testing on all test gases at reduced inlet pressure, passed all but one gas atnormal input and passed all gasses at overfire.

For almost all products, reduced inlet gas pressure is not something that results inincreased emissions, hence, those results were not detailed on the consolidated testsheets. An exception was made for sample # 57 which utilizes a ceramic Infra Redburner which typically, because of the burner’s inherent design, encounter issues at lowinputs or low manifold pressures rather than at high inputs or manifold pressures. Theimportant issue to be aware of is that within the low inlet pressure test mode, the effect ofhigher Wobbe Indexes can be seen in an inverse pattern, i.e., higher heating valuesimproved (but still failed) CO emissions while lower Wobbe Indexes (lower input)increased the CO production.

22

Room Heaters: Vented Fireplaces

Two (2) manufacturers provided a total of three (3) fireplaces for testing. All units weredirect vented products with inputs ranging from 17,500 up to 37,500 BTU/Hr. All ofthese were tested to the ANSI Z21.50 standard. All sample appliances are built-in designswith standing pilots. The manufacturers supplied logs and rock wool with specificlocations and coverage for flame effects. Test pressures and burner adjustments were asindicated for other product types; normal, reduced and increased inlet pressure tests alongwith 112% increased rate.

Notable Differences in Test Procedures from the Generic Information Given AboveStarting with the appliances at room temperature, after 45 minutes of continuousoperation, the rate must be within 100% to 105% of the manufacturer’s specified BTU/Hrrate. Flue samples were taken after two minutes of purge time when adjustments aremade to rates and/or pressure increases during the prescribed test procedures.

Fireplaces are one of only a few appliances which are permitted to have carbon (soot)deposits during operation, but the carbon deposits formed during the combustion processshall not affect the performance of the appliance. The standard instructs the tester todistribute loose burner material, such as simulated embers (if provided with theappliance), over the burner ports per the manufacturer’s instructions and then operate theappliance for 24 hours at normal inlet test pressure. Any carbon deposits that developduring the 24 hour period shall not be removed during the remainder of the tests.

Combustion Tests:All combustion samples were taken after two-minute purge time after adjustments weremade and one appliance failed Air Free CO operating on “D” gas at normal input.

Burner Operating Characteristics:One appliance failed ignition testing at reduced inlet pressures on “A” and “C” gases,along with slow ignitions (more than 4 seconds) at normal pressure on “C” gas. It failedall ignition tests on “E” gas.

Observations and Comments:One combustion failure was found on “D” gas operating at normal inlet test pressure.This failure was primarily due to the 105.5% increased rate at “normal” condition with alow CO2. This resulted in an Air Free CO of 432 ppm (limit for test was 400 ppm airfree).

23

Room Heaters: Vented Space Heaters

Two (2) manufacturers provided a total of (3) models with different designs thatincluded: direct vent, short wall mounted and a floor “hearth” type. Inputs ranged from14,000 BTU/hr up to 65,000 BTU/Hr with no fan-assisted combustion processes on anyproduct. The appliance breakdown is as noted below:

1 Direct vent hearth heater2 Direct vent wall mounted (short)

ANSI Z21.86 Vented Gas-Fired Space heating Appliances covers the broad range anddesign of these furnaces. All types must pass combustion tests with 400 ppm (0.04%) asthe Air Free CO limit. The overfire condition on natural gas is 112% of the data plateinput. Many of the test procedures are similar to the furnace standard for the combustiontest(s) and operational times for data taking.

Notable Differences in Test Procedures from the Generic Information Given Above

The ANSI standard has five specific sections covering the different design criteria foreach type of wall furnace. Vent systems are critical with the natural draft designs and testset-ups have specific configurations/diameters. Natural draft wall furnaces requiresufficient vent pipe to be added to the appliance such that the termination of the vent pipeshall be 12’ above the base of the heater/test floor. Using a standing pilot ignition systemrequires a warm up time before the combustion tests commence from a cold ambientstart.

Observations and Comments:The natural draft flue systems operating at increased rates have elevated AFCO with onefailing emission tests while operating at increased rate on B and D gases. Ignitionsystems consisted of standing pilots with milli-volt thermostat controls driven by thethermocouple or thermopile output voltage.

24

Pool HeatersIncluded with the Water Heaters information below.

Unit Heaters

Four (4) manufacturers contributed a total of four (4) unit heaters for this test program.All were power vented products with inputs ranging from 30,000 BTU/Hr to 250,000BTU/Hr. ANSI Z83.8 Duct Furnace and Unit Heaters is the standard for theseappliances. Most of the operational tests are the same or similar to the furnace standard.

Combustion Tests:The maximum Air Free CO is 400 ppm (0.04%) after 3 minutes at normal inlet pressures,an additional 2 minutes at reduced inlet pressure, a total run time of 15 minutes before theincreased rate combustion test, and followed up with reduced voltage (85% of ratingvoltage).

Burner Operating Characteristics:B.O.C. tests are similar to ANSI Z21.47 Section 2.9 for appliances with inlet pressuresless than 14 inches water column. They consist of 1/3 turn down, 87% of minimum input,4” inlet and voltage variations: 85 and 110 percent of rating plate voltage. These tests areto be performed at cold (room ambient) and hot test conditions.

Observations and Comments:An emission test failure was found on one sample appliance while operating on “B” and“D” gases; while operating on “B” gas the actual over-fire rate was measured at 117.2%.“D” gas increased rate was higher with an over-fire rate of 118.1%. Both of these gasescaused higher than allowable Air Free CO emissions. Blocked vent outlet test showedsimilar results on the two highest Wobbe Index gases, producing higher than the 400 ppmlimit for Air Free CO.

25

Water Heaters and Pool Heaters

Four (4) water heater manufacturers and one (1) pool heater manufacturer provided atotal of nineteen (19) water heaters and one (1) pool heater for inclusion in this program.There was a mix of both commercial and residential water heaters along with the onepool heater. Sample appliance breakdowns by type of the nineteen water heating productsare:

2 Residential Power Vented4 Residential Natural Draft2 Residential Ultra Low NOx2 Commercial Power Vented4 Commercial Natural Draft2 Residential Instantaneous Tankless1 Commercial Instantaneous Tankless1 Commercial /Residential Condensing1 Pool Heater

ANSI Z21.10.1 covers storage water heaters with input rates 75,000 BTU/hr and below.ANSI Z21.10.3 applies to storage water heaters with input rates higher than 75,000BTU/Hr and all instantaneous water heaters. ANSI Z21.56 covers pool heaters.

Notable Differences in Test Procedures from the Generic Information Given Above

The ANSI water heater standards have no “Normal” combustion test/CO requirement, butfor this program data was recorded for a “Normal” condition. Per the standards,combustion samples are required to be taken at reduced inlet pressure with an allowableCO of 200 ppm air free, and increased/overfire condition with an allowable CO Air Freeof 400 ppm. The overfire rate requirement is 106.25% for water heaters (see pool heatersdifference below). Hence, there is no CO allowable given for normal operation, and itcould be either 200 or 400 ppm.

For combustion testing the water heater is filled with 70 2 F water. The heater isplaced in operation and after fifteen minutes of continuous operation at normal inlet testpressure, the combustion testing begins with an additional five minutes of operation atincreased rate and then an additional five minutes of operation at reduced inlet pressure.If equipped with a fan/blower power combustion system, an additional test is run at 85%of line voltage (see further discussion below).

For the one pool heater included in the test program, the pool heater standard (ANSIZ21.56) requires an increased rate of 112% with AFCO requirement of less than 400 ppm(0.04%) at the increased rate. For both normal rate and reduced inlet pressure theallowable CO Air Free is 200 ppm (0.02%).

Combustion Tests;The combustion samples were taken at the water heater’s flue outlet without a ventsystem connected to the draft hood as detailed by the ANSI standard. Power vent

26

appliances are required to pass combustion tests at reduced voltage (85%) of data platestated voltage and with both the maximum and minimum vent lengths specified by themanufacturer. Again, to look at trends, only the minimum vent length was tested in thisprogram.

For an appliance equipped with a draft hood (atmospheric vented) two sample probeswere placed in the flue (on either side of the typical restrictor baffle) and joined togetherin order to obtain an average sample before dilution in the draft hood. Once the probesystem was placed in the appliance, it was “locked” in position and not moved for thetesting of the other gases. The goal being to have consistency of data in what,sometimes, can become a stratified sample.

As noted above the initial start up procedure requires the water heater to be filled with70º F water. For continuous operation, water flow through the water heater was adjustedto maintain a water outlet temperature of 130F with a 70ºF inlet water flow. In order tomaintain these requirements the 1,500 gallon tempering water system was used for allwater heater testing.

For almost all products, reduced inlet gas pressure was not something that resulted inincreased emissions; hence, those results were not detailed on the consolidated testsheets. An exception was made for sample # 53 (Atmospheric, Commercial Tank StyleWater Heater) which did experience issues at reduced inlet pressure. As the WobbeIndex decreased, the CO air free emissions levels increased and failed on gases “C” and“E”.

NOX: NOX emissions were recorded along with CO2 and CO samples, this extra data aidsin the determination of what effects the higher Wobbe Indexes had on combustionsduring the use of different gases. The reader is cautioned that the NOx emissionsrecorded were not done under the same protocol as required for California and TexasEPA emission testing. See the more detailed explanation under Boilers and Furnacessections of this report.

Burner Operating Characteristics:One Low NOX appliance had burner resonance noise at increased rates on both higherWobbe Gases (“B” and “D”).

Observations and Comments:NOX readings followed the changes in Wobbe Index wherein the higher Wobbe Index gasresulted in higher NOX emissions. One Low NOX appliance had burner resonance noiseat increased rate on both higher Wobbe Index gases.

Combustion failures were found primarily at increased rates on the high Wobbe “B” and“D” gases. One appliance failed while operating on “B” gas, but had passing results onthe highest Wobbe “D” gas. The cause appears to be due to a rate reduction on “D” gas,possibly due to excessive heat on the manifold pipe and orifice.

27

The decision was made to discontinue testing on one appliance (#64) that had failingcombustions operating on increased rate with “A” gas along with a failing “normal”condition on “B” gas. The data was left in the table because it does show that a“sensitive” product that just barely fails (or passes) the overfire condition on Gas “A” canbe dramatically impacted by a Wobbe change when tested at normal inlet pressure with agas that mimics the 106.25% overfire condition. The test difference was that on gas A atoverfire condition, the manifold pressure was increased to obtain the overfire. Bychanging the gas but leaving the manifold pressure at normal condition, the effect of ahigher input was much more dramatic than achieving the overfire by increasing themanifold pressure to achieve the overfire effect.

28

Tables

NoteWhen reviewing the individual data sheets, please be advised that any value of COrecorded as “1050” ppm means that the upper range of the CO measuring instrumenthas been exceeded. It was not determined how far above 1050 ppm the actual value was,but the 1050 value was used for computational purposes in determining the minimum AirFree CO value that the results could have been. Therefore, there are times where the COvalues may be recorded (air free) on the data sheets as 1200, 2000, or more ppm. This isjust the result of the mathematics of using 1050 ppm (maximum range of instrument) forthe CO value inserted into the air free calculation. Hence, the value is at least thenumber shown and may be much higher. Most likely any recorded CO air free valueover 1100 ppm in the tables was generated because the measured CO was above 1050ppm4.

4 To make that determination: Multiply the stated value in the table by 12.2% and then divide the resultantvalue by the recorded CO2. This will give the reader the base CO value used for the calculation.

29

Tables: Page 1

TestS

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Fu

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Comment on Venting, Efficiency, Sub-type of product, etc.

12 3 13 10 6 3 5 3 1 9 4 4 3 3 Number of samples tested/data presented (Total 78)

1 X High Effeciency ( 90+ ) Furnace

2 X 80 + Efficiency Furnace3 X 80 + Efficiency Furnace

4 X 80 + Efficiency Furnace5 X Heavy Duty 30" Freestanding Range

6 X Heavy Duty 48" Free Standing Range7 X High Effeciency ( 90+ ) Furnace

8 X 80 + Efficiency Furnace9 X 80 + Efficiency Furnace

10 X High Effeciency ( 90+ ) Furnace11 X Clothes Dryer

12 X Clothes Dryer13 X Clothes Dryer

16 X Non-Condensing Boiler Power vent17 X Clothes Dryer

18 X Clothes Dryer19 X Clothes Dryer

20 X 30" Free Standing Conventional Range21 X 80 + Efficiency Furnace

22 X 80 + Efficiency Furnace23 X Heavy Duty 48" Free Standing Range

24 X High Effeciency ( 90+ )25 X Clothes Dryer

26 X Cook Top28 X Unit Heater Power Vent Residential Garage Type

29 X High Effeciency ( 90+ ) Furnace30 X High Effeciency ( 90+ ) Furnace

31 X High Effeciency ( 90+ ) Furnace32 X Wall Oven

33 X Cook Top34 X Clothes Dryer (Apartment Size with Washer Attached)

35 X Clothes Dryer36 X High Effeciency ( 90+ ) Furnace

37 X Power Vent Boiler (80+% Efficiency)38 X Condensing (90+% Efficiency) Modulating Boiler

39 X Atmospheric Vent (Draft Hood) Boiler40 X Power Vent Boiler (80+% Efficiency)

41 X Atmospheric Vent (Draft Hood) Boiler42 X Atmospheric Vent (Draft Hood) Boiler

43 X Power Vent Residential Water Heater44 X Atmospheric Vent (Draft Hood) Residential Water heater

45 X Atmospheric Vent (Draft Hood) Commercial Water heater46 X Power Vent Commercial Water Heater

47 X Atmospheric Vent (Draft Hood) Residential Water heater48 X Tankless/Instantaneous Water heater

49 X Power Vent Boiler (80+% Efficiency)50 X Atmospheric Vent (Draft Hood) Boiler

51 X Condensing (90+% Efficiency) Modulating Boiler52 X Condensing (90+% Efficiency) Modulating Boiler

53 X Atmospheric Vent Commercial Water Heater54 X Cook Top

55 X 30" Free Standing56 X Tankless/Instantaneous Water heater

57 X Ceramic Infra Red Style Unvented Room Heater58 X Atmospheric Vent Ultra Low Nox Residential Water Heater

59 X Power Vent Residential Water Heater

30

Tables: Page 2

TestS

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Comment on Venting, Efficiency, Sub-type of product, etc.

60 X Atmospheric Vent (Draft Hood) Residential Water heater61 X Tankless/Instantaneous Water heater

62 X Power Vent Commercial Water Heater64 X Atmospheric Vent (Draft Hood) Commercial Water heater

65 X Atmospheric Vent (Draft Hood) Commercial Water heater66 X Wall Furnace

68 X Atmospheric Vent (Draft Hood) Residential Water heater69 X Atmospheric Vent Ultra Low Nox Residential Water Heater

70 X Condensing (90+% Efficiency) Water Heater71 X Wall Furnace

72 X Wall Furnace75 X Fireplace Concentric Direct vent

76 X Pool Heater77 X Fireplace Concentric Direct vent

78 X Fireplace Concentric Direct vent80 X Unit Heater Commercial Size

81 X Unit Heater Power Vent Residential Garage Type82 X Blue Flame type unvented room heater

83 X Blue Flame type unvented room heater84 X Unit Heater Commercial Size

85 X Condensing (90+% Efficiency) Modulating Boiler

86 X Gun Style Power Burner (80+ % efficiency)

Some products submitted were not tested because they did not meet the parameters of the test program

31

32

33

34

35

36

37

38

39

40

41

42

43

44

45

46

Appendix

47

Chart of Test Gases

GAMA Designation Baseline High Low Higher Lower

Heating Value 1035 1110 985 1140 985

GCI Designation Gas A Gas B Gas C Gas D Gas E

Specific Gravity 0.5903 0.6112 0.5830 0.6353 0.6396

Wobbe Index 1345 1405 1290 1430 1230

% Wobbe Index Change fromTest Gas A 0.0% + 4.4% - 4.09% + 6.32% - 8.55%

COMPONENT Mol % Mol % Mol % Mol % Mol %

CARBON DIOXIDE 0.50 0.00 2.50 0.00 2.00

NITROGEN 1.40 0.20 0.60 0.00 6.70

METHANE 94.38 91.50 96.59 89.50 84.88

ETHANE 2.80 6.00 0.30 6.00 5.40

PROPANE 0.60 1.50 0.01 3.00 0.80

I-BUTANE 0.00 0.00 0.00 0.00 0.00

N-BUTANE 0.20 0.80 0.00 1.50 0.16

I-PENTANE 0.00 0.00 0.00 0.00 0.00

N-PENTANE 0.10 0.00 0.00 0.00 0.04

HEXANES PLUS 0.02 0.00 0.00 0.00 0.02

TOTAL 100.000 100.000 100.000 100.000 100.00

48

List of Test Standards Used

Z21.1 Household Cooking AppliancesZ21.5.1 Type 1 Clothes DryersZ21.10.1 Storage Water Heaters With Input Ratings of 75,000 Btu Per Hour or LessZ21.10.3 Storage Water Heaters With Input Ratings Above 75,000 Btu Per Hour,

and Circulating and Instantaneous Water HeatersZ21.11.2 Gas Fired Room Heaters, Vol. II Unvented Room HeatersZ21.13 Gas Fired Low Pressure Steam and Hot Water BoilersZ21.47 Gas Fired Central FurnacesZ21.50 Vented Decorative AppliancesZ21.56 Gas Fired Pool HeatersZ21.86 Vented Gas-Fired Space Heating AppliancesZ21.88 Vented Gas Fireplace HeatersZ83.8 Gas Unit heaters and Gas Fired Duct furnaces

49

50

Wobbe Index

Throughout this report the term “Wobbe Index” will be used to denote different gasesbeing utilized in the test program. Although the term is well understood by staff of thegas utilities and European gas engineers, it has not gained much usage (until recently)within the North American gas appliance industry.

In a simplistic fashion most people will equate a shift in heating value as meaning achange in heat output of the appliance on a one to one basis, but this is not necessarily thecase because gas flow through an orifice is also controlled by a number of factors, one ofwhich is the specific gravity of the gas that passes through the orifice (Specific Gravity ofair = 1.00).

Generally the heat input of an appliance or burner is given as:

BTU/Hr = H.V. X QWhere:

H.V. = Heating Value of the gas (by convention in North America we useGross or Higher heating value for our calculations)Q= Flow of gas in Cubic Feet per hour

And Q can be shown (in English units) as:

Q= 1658.5 k A (∆P÷S.G.)½

Where:k = k factor of orifice (a constant generally related to the internal geometryof the actual orifice)A= Area of orifice in square inches∆P= Pressure differential (in inches water column) across the orifice face (In most gas appliance applications this is simply the manifold pressureexpressed in inches of water column and assumes no losses throughinternal plumbing downstream of the pressure tap)S.G. = Specific Gravity of the gas flowing through the orifice where air =1.00

And if only the medium flowing through the orifice changes, i.e. the gas mixture, but thek factor, ∆P, and A remain unchanged (which will be the case of an operational appliance), the change in flow (Q) is only related to 1/(S.G.) ½

Or the change in heat input (BTU/Hr) of the appliance is related to

Input ≡ H.V ÷ (S.G.) ½

The above term or equation is known as the Wobbe Index. With the result being that ifthe Wobbe Index of a gas changes by some percentage (say +8.1%) compared to anothergas, the actual gas input of the appliance will increase by 8.1%. So an appliance that mayhave had an input of 100,000 Btu/Hr on the original test gas will now have an input ofapproximately 108,100 Btu/Hr.

51

Gas Heating Value and Specific Gravity

To the layman the term “natural gas” implies some kind of unique compound that has achemical formula and remains unchanged no matter where one goes to get their naturalgas.

In fact, as gas wells are drilled into the ground, the gas that comes out is a “mixture” ofdifferent compounds that do not bind to one another but stay as independent moleculeswithin the mixture. The physical characteristics of the gas mixture are generally the sumtotal of each of the individual characteristics of each of the compounds. Hence, if wehave a way to measure each percentage of each individual constituent within the gasmixture we can compute the heating value and specific gravity of the “final” mixturealong with a number of other constants such as specific heat, etc..

Generally it is recognized that a gas mixture which contains 80% or more methane gas(CH4) is termed a “natural gas” but the remaining other compounds within that mixturewill greatly influence the final physical properties of the “final” gas which will begenerically termed “natural gas”.

From the ASTM tables in D3588-98 (Standard Practice for Calculating Heat Value,Compressibility Factor, and Relative Density of Various Gases Fuels) we can look up thephysical constants for the compounds that are naturally found in a gaseous fuel such as“natural gas”. By passing the gas mixture through a gas chromatograph, the actualpercentage of each compound can be determined and this is a standard practice at mostutilities.

A typical mixture may have a composition similar to the one on the following page. Theexample on the next page was actually taken from data for one of the suburbs ofCleveland, Ohio near where one of the gas national appliance testing laboratories islocated, and represents the typical gas natural most appliances are tested on when goingthrough that laboratory.

From the data it can be seen that approx. 10 % of the gaseous compounds in this mixtureare other than methane gas (CH4).

52

East Ohio GasGas Analysis Laboratory

Analysis of Gas Phase Arcco Sample

1. Source: TPL 7, Twinsburg Station, EOG #83606, Serial #72262. Sample Period: 7/21/97 to 8/19/973. Sample Number: 9708n0914. Gross Heating Value: 1039.8

(BTU/SCF @ 14.7 psia, 60 F, dry basis)5. Specific Gravity: 0.6093

(density relative to air = 1.00)6. Wobbe index: 1332 Btu/Ft37. Chromatographic Analysis:

Component NormalizedVolumePercent(Time

Averaged)

ASTMConstant

H.V.(Gross)

H.V.Contribution

to FinalMixture

ASTMConstantfor S.G.

S.G.Contribution

to FinalMixture

Helium 0.03 0 0 .1382 0.00004Hydrogen 0.01 342.2 .03422 .0696 0.000007Oxygen &Argon

0.02 0 0 1.1048 .00022

Nitrogen 2.63 0 0 .9672 0.025Carbon Dioxide 0.51 0 0 1.5196 .00775Methane 90.38 1010 912.83 .5539 .5006Ethane 5.31 1769.7 93.97 1.0382 .0551Propane 0.69 2516.1 17.36 1.5226 .0105Iso-Butane 0.09 3251.9 2.93 2.0068 .00181N-Butane 0.15 3262.3 4.89 2.0068 .00301Neo-Pentane 0.00 4008.9 0 2.4912 0Iso-Pentane 0.05 4000.9 2 2.4912 .00125N-Pentane 0.04 3985 1.59 2.4912 .000996Hexane 0.08 4198.1 3.788 2.9755 .00238

Total 100.00 1039.1 .609

Note: The calculations in the chart above (done for this report) are simple percentagecalculations and do not take into account the gas compressibility factors. That omissionmay add up to a 1 BTU/Ft3 error. Values above the chart utilize the full ASTMcalculation procedures including gas compressibility factors.

Analysis Based on ASTM D3588-89 using gas chromatography

53

Discussion of Air Free Sampling Procedures

The term “air free” sample is used though out this report. The concept within all safetystandards (North America, Europe, Pacific Rim such as Japan, etc.) for the measurementor emissions from a combustion process such as a gas appliance is to determine theconcentration of the effluent at its source, i.e. the burner, before it is diluted with excessdilution air. The measurement process is referred to as “… on an air free basis”, or insome standards it is referred to as “... computed for no excess air”.

In the case of vented gas appliances, the concentration of products in the flue pipe thatconveys the products outdoors from a heating appliance has been diluted substantially byexcess air that is incorporated in the design of the appliance. The excess air is very oftenused to cool the flue products down to extend the life of metal heat exchangers andbaffles within the appliance that are utilized for increasing the efficiency of the heattransfer process and to reduce the risk of fire of surfaces near the flue pipe itself..

By requiring the “air free” value of an effluent such as CO, it does not permit anappliance to pass the emission test by deliberately adding extra dilution air to the totaleffluent to get the final value below the acceptable limits. Hence, all manufacturers ofgas appliances are on an equal footing as to how they make their burner perform in orderto comply with the safety standards.

Within the combustion process there is a “marker” that stays constant that can be used fora dilution calculation . The concentration of CO2 remains fixed in the combustionprocess and only depends upon the general gas type (natural gas, LP gas, etc.). We knowthat when one burns natural gas that the percentage of CO2 produced by the burning ofthe gas (at the burner ports) will be approximately 11.9% and only depends upon thecomposition of the natural gas and varies no more than ±0.3% for all natural gases. Theterm for this CO2 value is called the “Ultimate CO2” or “Stoichiometric CO2”. For LPgases the value increases to 14.0%.

On the other hand the amount of other effluents in the gas combustion process such asCO, UH (Unburnt Hydrocarbons), CHOs (aldehydes, formaldehydes, alcohols, etc), NO(Nitrous Oxide), NO2 (Nitrogen Dioxide) where NO + NO2 = NOx, are all variablesthat depend upon the appliance design, burner adjustment and the final values will varygreatly from one model of product to another, let alone from one manufacturer to another.

By using the Ultimate CO2 as a constant within the combustion process it is possible tomeasure the amount of CO2 at the same point where the other effluents are measured anddo a very simple calculation that arrives at the concentration of the effluent at the sourceof the process (the burner ports). For many reasons it is impracticable to measure theeffluent at the burner ports, so it is necessary to get a more uniform measurement remotefrom the burner ports and for heating equipment a convenient point is in the exhaust pipe.When doing this one must understand that the effluent will be diluted from the values atthe burner ports.

Example: Let us say we had a “virtual” instrument that could measure the effluent rightat the burner ports and we found that the CO2 was 11.9% (as we know should happen bythe chemical equations) and the CO was at 900 ppm (same as 0.09%) and the NOx was at126 ppm. The flue products leave the burner and travel through a number ofpassageways within the appliance and finally find their way into the exhaust pipe. Alongthe way to the exhaust pipe, additional air is entrained into the appliance to cool the flue

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gases (effluent) down to prevent metal fatigue. When the effluent is measured at theexhaust pipe we find that the CO2 value is 3.4 %, the CO is 257 and the NOx is 36ppm.

Since we know the burner combustion process must generate 11.9% CO2, we will use thisas the constant in the calculation to determine a dilution factor. Since we measure 3.4%CO2 in the exhaust pipe, the dilution factor is 11.9% ÷ 3.4% = 3.5.

Therefore, all other effluents measured in the exhaust stack have likewise been diluted bya factor of 3.5. Therefore, the CO on a non diluted basis or “air free” basis would be:

Measured CO = 257 ppm multiplied times the dilution factor of 3.5, givesCO on an air free basis as: 257 x 3.5 = 900 ppm and theNOx value on an air free basis is 36 ppm x 3.5 or 126 ppm of NOx.

Therefore, although the CO from the exhaust stack is under the allowableof 400 ppm required in most heating equipment standards, the actual airfree basis of measurement is well over the 400 ppm value.

Therefore, the formula for CO air free is:

COair free = (Ultimate CO2 ÷ Measured CO2) x Measured CO

And the ultimate CO2 for natural gas in Cleveland is typically about 11.9%*

(for LP gases Propane is approx. 13.8 and Butane is approx. 14.0%)

* Historical Note: For a number of historical reasons and again in an attempt to provideto utmost cushion of safety for gas appliances, one national testing agency still uses ahistorical Cleveland value of 12.2% in their calculation process, as this makes it slightlyharder to pass the tests required in the standards. Hence, to create the upmost cushion ofsafety for this program, GCI has elected to use the same value for all calculation of airfree values.

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Above: Banks of 5 test gases

Below: Test cart for controlling 5 test gases plus house gas