by Norbert Senf,
Chair of the Masonry Heater Association Technical Committee
Left to right: Mark Champion (in his
VT test lab), Boris Kukolj (Tulikivi),
Chris Prior (MHA President), Norbert
Senf (blog author) and Jean Francois
Vachon (soapstone supplier).
Photo credit: Mark Seymour.
EPA started regulating wood burning stoves for particulate (PM) emissions in 1988. Regulation was limited to airtight heating stoves. Masonry heaters were not regulated, the stated reason being that they were likely to be clean burning.
In Europe, only carbon monoxide (CO) emissions were regulated. CO is easy to measure, however PM can be very tricky. Wood smoke includes
compounds that will only be captured by a filter if you cool them down and condense them. This is done in the laboratory by mixing them with air in a dilution tunnel, and this is thought to simulate what happens in the ambient air in the real world.
State and county air quality authorities soon started to address wood smoke, and would often pass a generic local regulation that banned all appliances except those that were EPA certified. We, the fledgling Masonry Heater Association (MHA), decided to seek EPA certification.
Although we “knew” that masonry heaters were cleaner even than EPA stoves, nobody had ever measured the PM on one with the dilution tunnel method. With funding help from the Wood Heating Alliance (now HPBA), we were able to participate in a $ 100,000.00 test method development project for masonry fireplaces and masonry heaters. The project took place at Virginia Polytechnic Institute (VPI) in 1989 and was headed by Dr. Dennis Jaasma.
The results were interesting, with some surprises. EPA did not accept the proposed test method. We immediately realized that we needed do a lot more testing,
and that we would need to develop the capability to do it ourselves.
We were fortunate in being able to arrange for training with OMNI-Test, one of the leading EPA-accredited certification testing laboratories, then and now. OMNI developed a training session for us that took place in September 1996. It included presentations by regulators, an emission chemistry expert (Dr. Jim Houck), and laboratory testing personnel. Dr. Stockton (Skip) Barnett showed us the low cost portable dilution tunnel that he invented, known as the Condar. He developed it while working for the Condar Company. It was widely used at the time by the major stove manufacturers for in-house testing to develop their certified stoves.
The attached Powerpoint
, Repeatability of Cordwood Combustion Particulate Measurements,
presents a summary of the work we have done at the Masonry Heater Association
to calibrate the Condar against the EPA Method 5G laboratory dilution tunnel. It includes a close look at the PM testing repeatability issues,
a major discussion point over the years. We have recently completed 2 cordwood studies, using very carefully matched loads in a masonry heater. Repeatability was within plus or minus 15% – 25%, depending on the ignition method. With crib fueling, we were able to get within 10% repeatability on PM, and within 1.5% repeatability on CO.
One of the loopholes in the new EPA regulations about to close
|The cleanest and most efficient
forced air furnace is the Maine
Energy System Auto Pellet Air.
It delivers 89% efficiency.
One of the big loopholes in the new EPA wood and pellet heater regulations is closing this month.
Small forced air furnaces were required to meet new emission regulations in May 2016, but many very small furnaces declared themselves to be large furnaces, giving them until May 2017 to meet the new standards
As of May 16, 2016, all forced air furnaces, large and small, must emit no more than 0.93 lbs per mmBTU of heat output regardless of whether they are wood or pellet units.
Currently, there are six forced air furnaces that are certified, four of which use wood and two of which use pellets.
The average emissions rate ranges between 0.06 to 0.84 lbs, with the average at 0.411 lbs, less than half the current standard.
However, as of 2020, this class of heaters must meet a far stricter standard of 0.15 lbs/mmBTU.
(This is the subject of litigation by the HPBA.)
Only one of the current six models, the Maine Energy System Auto Pellet Air
emits less than 0.15 lbs, but it has to be retested using a different test method to comply with the 2020 standards.
Of the six currently on the market, there is a huge efficiency range, from 48% to 89%. Both ends of the spectrum are listed as pellet heaters. At the top end is the Maine Energy System’s Auto Pellet Air, which was developed by OkoFEN
, a leading pellet boiler company in Austria. At the bottom end is US Stove’s 8500 multi-fuel furnace
(US Stove also has a certified cordwood furnace that has lower emissions and higher efficiency than this pellet model.) The average efficiency of the six
|The US Stove 8500 pellet
furnace is the least efficient
certified furnace at 48%, but sells
for less then $ 3,000.
furnaces is 66%.
At the end of May 2017, it will be clear how which forced air furnaces did not get certified.
There are many more coal furnaces on the market today, compared with 3 or 4 years ago, as some companies have added grates and other slight modifications to outdoor wood boilers and furnaces in order to keep them on the market as coal units.
Coal heaters are still not covered by EPA emission regulations, so renaming a wood boiler or furnace a coal boiler or furnace is still a loophole used by some companies.