NSPS Revision Recommendations

• Test Methods

• Product Types

• Efficiency

• Emissions Units

• Certification

• Fueling Procedure

• Other Issues

Rick Curkeet, PE

Chief Engineer
Test Methods

• Replace EPA Methods with Consensus Standards

– Emissions Measurement – ASTM E2515 

– Outdoor Hydronic Heaters – ASTM E2618

– Fireplaces – ASTM E2558

– Wood/Pellet Stoves – CSA B415.1 (New version) or 

ASTM if Available.

– Forced Air Furnaces – CSA B415.1 (New Version)

• Advantage – Consensus Standards are Preferred.

– OMB Circular A119

– Consensus Standards are updated and revised on a 

regular basis to improve and keep pace with new 

technologies.
Product Types

• Coverage should be expanded to cover all 

common types of bio-mass fueled appliances. 

– Furnaces

– Boilers/Hydronic Heaters

– Pellet/Corn/Grain burning heaters

– Cook Stoves

– Masonry Heaters

• Not being included in regulatory system leads to 

being excluded from some important markets.
Efficiency

• All heating appliances should be tested and rated 

for heating efficiency.

• CSA B415.1 will include an updated and reliable 

“Stack Loss Method” for direct heating appliances 

such as wood stoves and pellet type appliances.

• Furnaces and Boilers should be rated for delivered 

efficiency based on direct measurement of heat 

output.

• Critical to have recognized test methods to 

support US tax credit incentives.

Heat Input

Comb. Loss

Heat Transfer Loss

Delivered Heat
Emissions Units

• All Heating Appliances should be rated and regulated for 

emissions on a particulate mass per unit of heat output 

basis. 

– Grams/Mega Joule (g/MJ)

– Lbs/Million BTU (lb/MMBTU)

• Provides a fair approach for consistent requirement for 

different types of solid fuel heating appliances.

• Automatically incorporates incentives to improve 

efficiency.

• Non-Heating Appliances (e.g. Fireplaces) should be rated 

and regulated based on mass per unit of fuel burned –

e.g. grams/kilogram (g/kg).
Emissions Units

• Existing EPA “emissions adjustment factor” to convert 

EPA method 5G to Method 5H equivalent (Eadj = 1.82 x 

EMeas

0.83 ) should be dropped and limit stated in unadjusted 5G (ASTM E2515) values.

• This would change nothing in terms of the result 

necessary to meet a specified limit and would remove a 

very dubious issue from the process. The size of the 

correction gets larger as emissions decrease which is not 

correct (see next slide).

• Example – If the current method’s limit where set at 4.5 

grams/hour, the unadjusted 5G result would need to be 

3.0 grams/hour. This would equate to 0.2 g/MJ or 0.46 

lb/MMBTU based on the current non-catalytic woodstove 

default efficiency of 63%.
Eliminate 5G to 5H “Correction”.

EPA Method 5G to 5H Correction Factor

0.0

0.5

1.0

1.5

2.0

2.5

3.0

0 1 2 3 4 5 6 7 8

Measured Emissions Rate (g/hr)

Corection Factor

0

1

2

3

4

5

6

7

8

9

10

Corrected Emissions (g/hr)

Correction Factor "Corrected" Emissions
Certification

• Emissions and Efficiency Certification 

should be handled through “Third- Party Certification” per ISO/IEC 

Guide 65.

• This process is already in use for 

“Safety Certification” of nearly all the 

appliances involved.

• It includes a robust and reliable 

follow-up inspection process that 

assures on-going conformance of 

individual production units.

• Much more efficient and reliable than 

the NSPS Random Compliance Audit 

program that has never been 

implemented.

Particulate Emissions and Heating 

Efficiency Certified per ASTM 

E2618-08

Manufacturer: ODHH Inc.

Model: 150 Clean Heat

Serial #: 123456

Particulate Emissions Rate: 0.13 lb/mmBtu Output

Use: Heating Season Only.

Delivered Heating Efficiency: 76%

Maximum Heat Output: 128,000 Btu/hr w/ reload at 

2.5 hr. intervals.

8-Hour reload output: 85,000 Btu/hr.

Fuel: Seasoned Cordwood only.

Particulate Emissions

0 lb/mmBtu Output 0.60

 Better Worse

This Model 0.13

Delivered Heating Efficiency

0 Percent 100

 Worse Better

This Model 76%

IMPORTANT: THIS APPLIANCE IS INTENDED TO BURN 

SEASONED CORDWOOD FUEL ONLY. OPERATE IN 

ACCORDANCE WITH MANUFACTURER'S OPERATING 

INSTRUCTIONS ONLY. FAILURE TO OPERATE THIS APPLIANCE 

AS DIRECTED MAY RESULT IN VIOLATION OF AIR QUALITY 

REGULATIONS AND SUBJECT THE OPERATOR TO 

ENFORCEMENT ACTIONS INCLUDING FINES AND/OR REMOVAL 

ORDERS.
Certification

• Involves no cost to regulatory agencies and minimal 

cost to manufacturers or consumers as the process is 

already required and functioning for product safety 

certification.

• Third-Party Agencies already available and active in 

this area. 

• Process is based on internationally recognized 

standards.
Fueling Procedure

• All solid fuel burning appliances should be rated for 

emissions and efficiency performance with the fuel that 

they are intended to burn.

• Arguments for the use of cribs have not been supported by 

data available.

– Cribs do not provide significantly better reproducibility than 

cordwood. 

– Cribs do not provide a reliable indication of real world 

performance.

– Cordwood can be specified in a manner that provides a good 

representation of typical real world operation.

• Pellet Burners are tested with pellets, corn burners with 

corn, etc.
Other Issues

• Burn Rates

– The requirement for wood stoves to operate at under 1 kg/hr burn rate 

should be dropped in favor of the minimum being a percentage of the 

maximum. 

– This requirement has been unnecessarily design restrictive. 

– The CSA B415.1 burn rates - <35%, 35 - <53%, 53 - <76% and 100% 

should be considered. The average low burn rate for all EPA certified 

woodstoves and pellet burners is 28% of the maximum.

– Consider going to 3 burn rates rather than 4.

• Fuel Species 

– Fuel should be specified based on density range rather than species. Data 

indicates that fuel density is a more significant contributor to variability in 

results than species. Changing this requirement would make it easier for 

labs and manufacturers to obtain specified fuel locally.

– This approach would be consistent with long standing practice in Europe.

EPA Certified Stoves

0

50

100

150

200

10% 15% 20% 25% 30% 35% 40% 45% 50% 55% 60%

Minimum Burn Rate % of Maximum

Number of Models
Other Issues

• Eliminate “Gram per Hour Caps” in regulatory requirements.

– A gram per hour emissions cap serves to limit the output rate of 

affected appliances which actually burn very cleanly.

– For example, a cap of 18 grams/hour limits the output of an appliance 

that would meet a 0.2 g/MJ (0.46 lb/MMBTU) limit operating at 80% 

efficiency to a burn rate of 5.7 kg/hour and a maximum output of 

86,000 BTU/hr.

– Where heating applications require larger heat demands, caps could 

result in users being forced to buy fossil fueled appliances rather than 

using renewable bio-mass fueled equipment. Alternatively users 

might buy multiple smaller units to meet a larger heating demand 

application to work around the cap issue. 

Maximim Heat Output Rating 

All EPA Certified Stoves

0

20

40

60

80

100

120

140

160

180

10 15 20 25 30 35 40 45 50 55 60 65 70 75 80

Max Output (1000 Btu/hr)

Number of Units
Other Issues

• Consider revision to the “5-minute start-up” requirement for 

manually controlled appliances.

– It is well known that start-up with a fresh fuel load can be critical in 

obtaining good combustion performance.

– The 5-minute limit seems arbitrary and over-rides reasonable 

manufacturer’s operating instructions.

– Many of the so-called “outliers” in EPA woodstove test programs are 

simply the result of failure to operate at a high burn setting for long 

enough to establish and sustain secondary combustion. 

– Real world performance would benefit from more specific instructions 

to the user on how to assure good start-ups when reloading. 

Laboratory testing should include following such instructions provided 

they are clear and reasonable.