Ratings of Pellet Stoves

October 2015

An Independent Performance Review of Six Stoves

Download a pdf copy of the report here
Pellet stoves are regarded by many as a relatively new technology. However, they have been on the world market for more than 30 years. This renewable heating technology that began in the early 1980’s now provides heat for more than one million households in the United States and has proliferated world-wide. Last year, two out of every five wood-burning stoves sold in the United States burned wood pellets as a fuel.

A traditional woodstove uses stick-wood or cord wood as fuel and requires no electricity. Pellet stoves burn a densified wood made from sawdust that is compressed into a pellet form. Almost all pellet stove share electronic controls and motors to feed the pellets into the burn pot and automate the combustion process.

Figure 1. The six pellet stoves running during the 30-day trial.
Pellet stoves are now becoming an accepted source of reliable heat that displaces enormous quantities of fossil fuel and may soon outsell their traditional cousin – the wood stove.

A pellet stove with a full hopper of fuel can run unattended for twelve to 48 hours and offers a cleaner, more modern solution to wood heating.

Purchasing a pellet stove can still be a confusing endeavor. This report provides performance reviews of six popular pellet stoves and provides consumers with important background for what to consider in any pellet stove purchase.

The Alliance for Green Heat bought six of the most popular American and European pellet stoves currently on the US market to conduct independent testing of their cleanliness, efficiency, and ease of use.

A big question for many appliances (solar panels, geothermal systems, VW cars, etc.) is whether the technology performs as well in the real world as it does in a test lab. Our testing focused on this and found that most of the pellet stoves we tested operated very similarly in “real world” conditions as they did in the lab.

We found, however, that popular pellet stoves did not live up to the efficiency expectations of many consumers and government agencies. While there are likely high efficiency pellet stoves on the market, we observed only lower to medium efficiency in the six models that we tested, despite claims made by their manufacturers. We also found that some of the stoves and the glass on the door needed much more frequent cleaning than others.

We tested the six stoves running them nearly twenty-four hours a day for thirty days. We purposefully did not clean them as often as the owners’ manuals recommended in order to study how efficiency, emissions and overall operation would be affected by operators who neglected to clean them, which is common.

We tested them for performance attributes and rated them on five key things that consumers (and environmental stewards) care about: cleanliness, heating efficiency, required maintenance, heat output, and visibility of glass.

Figure 2. Power settings during the thirty-day testing period.
What makes our testing credible, reliable, and unusual is that we purchased the stoves and tested them side-by-side, using the same fuel and without the involvement of any stove manufacturer. During our endurance testing the stoves were monitored every day at various settings and the results were averaged over a thirty-day period (Figure 2). By using the same pellets on all the stoves, we reduced anomalies that can result when different labs test stoves with pellets from various manufacturers that have very different moisture, BTU and ash content. For more detail on how tested the stoves, click here.

The testing we performed and this report are one facet of a year-long Pellet Stove Design Challenge, that culminates in an intensive three day pellet stove workshop and design competition at Brookhaven National Laboratory in April 2016. To sign up for the workshop, click here, and to submit a stove or prototype, click here.

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