Harman and Quadra-Fire provide BTU input figures on their websites. Piazzetta claims their figure is BTU output. Ravelli and Enviro do not stipulate if they are quoting input or output BTU figures.

Our BTU output calculations compared the stoves against each other based on their tested feed rate (pounds of pellets delivered to the combustion chamber per hour) and an assumed average efficiency of 67%. Test labs report BTU ranges to the EPA that are then recorded on the list of EPA certified wood stoves, but test labs did not have to use actual efficiencies. Virtually every pellet stove reports similar BTU output at its lowest burn rate setting, falling somewhere between 8,000 and 12,000 BTUs per hour. But manufacturers, including four whose stoves we tested, somehow claim far higher BTU output on their promotional literature than the test labs reported. We do not recommend using BTU output claims in promotional literature, as it appears to be another area, like efficiency, where manufacturers can exaggerate numbers.

One reason test labs may report higher BTU output than we found is because they could have used the old EPA default efficiency of 78% for pellet stoves or even higher, instead of the actual efficiency of the stove, using the EPA approved method (CSA B415). They also may have been able to report numbers using European calculations (LHV) instead of those preferred in the US (HHV).1 The ability and willingness of manufacturers to claim far higher BTU output in their promotional literature than the EPA accredited labs reported points to a lack of industry or government guidelines for consumer advertising and may be perceived by consumers to be deceptive.

Can a pellet stove efficiently heat a home? Many consumers have years of experience heating a 1,500 – 2,500 square foot home with nothing more than their pellet stove. Of course, floor layout, insulation and region of the country are huge factors. A helpful guide of where a stove should be installed is typically within 25 feet of the common area of a home. Stoves in spare rooms or rooms above garages typically do not heat as well as a stove located within the insulated space near the center of the home. Sizing the stove is important because pellet stoves are not designed to be operated 24/7 at their highest heat setting. If your stove is undersized, it will likely have more performance issues than one that is correctly sized. Likewise, if you are just trying to heat an 800 – 1,200 square foot space, a smaller stove like the Ravelli or Englander will likely perform better.

Another consideration in stove sizing is recovery, or how long it takes to bring a cold home up to temperature. Smaller stoves will have a much longer recovery period than a large stove. A large stove with a good turndown ratio is ideal when considering the stove as a “whole home” heater. You get the best of both, quick recovery, but when demand is met, the stove can idle comfortably or if it has a thermostat, can modulate or even turn off and on as required.