Monday, May 1, 2017

All wood and pellet furnaces must be certified by May 15, 2017

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.

In April 2017, there were six certified forced air furnaces, 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 on the market in April 2017, there is an 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 was the least efficient
certified furnace at 48%. Now, US Stove
has a 33% efficient log wood furnace. 
furnaces is 66%.

(June 2017 update: There are now 10 certified furnaces on the market, with an average of 60% efficiency and a huge range stretching from 33% to 89%.)

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.


  1. Hi John, aren't there more than 10 units tested with CAN/CSA B415.1-10 for forced-air furnaces (cordwood and pellets)? I thought I would have seen more than 10 by now! Really surprised the industry haven't used this well known standard and stack loss method for %HHV efficiency.


  2. This topic has been causing a buzz in the industry. For Canada the manufacturers of wood stoves are in the U.S. anyway and our regulations up here follow the same way generally. This is good information for anyone wondering about their wood or pellets.