Wood and pellet stove companies that you can trust – and those you can’t

When it comes to listing accurate efficiency and BTU output on their websites, there are only a handful of companies that you can trust.

Updated on January 11, 2018 - For years, wood and pellet stove companies have listed exaggerated efficiencies and BTU output on their websites and brochures and no agency has challenged them for this practice.  Luckily, the EPA has started to list efficiencies on their list of certified stoves, so consumers have a easy way to check company claims.  

Most wood and pellet stove manufacturers use a variety of ways to say their stoves are more efficient than they actually are, and that they put out more heat than they actually do.  BTU output is the other area where manufacturers routinely report misleading data to consumers.  In the case of BTU output, even the EPA was willing to post those exaggerated numbers on its website, further contributing to the problem.

These issues are coming to light in the wake of new EPA regulations that require more accurate reporting and require manufacturers to post the test reports of independent labs that certify wood and pellet stoves.  Many stove manufacturers are not complying with the new rules and will not post their certification reports for consumers to see but some companies are complying.

A few companies stand out for providing the same efficiency numbers to their consumers as the independent test lab provided to the EPA.  They are: Blaze King, Jotul, Kuma, J.A. Roby, Seraph, Travis and Woodstock Soapstone.  Consumers can trust the efficiency numbers that these companies post on their websites and in their promotional materials.  

The same is not true of other companies, including many leading brands.  Most companies list efficiencies using the European (LHV) method, which can produce efficiencies of more than 100% and make their stoves appear 5 - 8 points higher than they actually are.  But some companies go further, publishing efficiencies that are 15 - 29 points higher than they actually are. 

The largest stove maker in the country, Hearth & Home Technologies (HHT), that owns Dutchwest, Harman, Heatilator, Quadra-Fire, Vermont Castings and others brands, published test lab reports for all their brands, several weeks after this blog first came out (in May 2016), which noted that they had not complied.  The company also says that actual efficiency numbers from independent test labs are recorded in the owners manuals in their stoves.  The result is that consumers see the exaggerated LHV efficiency on the brochures and website and then see the real number, often 5-10% lower, in the fine print of the owners manual.

HHT companies provide their lab reports on pages like these for Quadrafire, Harman.  For those and other HHT brands almost all the lab reports pre-dated the new EPA regulations, so actual efficiencies and BTU output are not included.  HHT has declined to voluntarily disclose efficiencies, like companies such as Jotul and Hearthstone have done.

One of the foremost experts in the hearth industry Dr. James Houck, an adjunct faculty member at the University of Portland in Oregon, used to work for Omni Test labs, the most well known test lab in the US.  He says, “Many of the pellet (and cordwood) stove efficiency values have been produced by commercial labs which optimized conditions and calculation methods." 

A wood stove test lab.

Under the new EPA stove regulations, known as New Source Performance Standards (NSPS), labs may be more restrained from optimizing conditions and calculation methods and will be producing more accurate efficiency and BTU output numbers for consumers.  Still, labs are under pressure from their clients to produce the best possible emission, efficiency and BTU numbers, or they may take their business to a lab they think can produce the best numbers.

The new EPA rules are requiring the test labs to produce more accurate BTU output data, which is crucial for consumers to right size the appliance for their home.  The result will be that BTU figures posted by the EPA after May 2015 when the new rules began will be lower than the figures posted before May 2015.  

The EPA has not started enforcing some of the provisions of the 2015 regulations which are being ignored by many companies. And, its enforcement capabilities are slim, a fact that is not lost on the industry that it regulates. State agencies could help enforce the new regulations, particularly for manufacturers based in their states and if stakeholders in the state pressure them to do so.

Under the new rules, an independent lab testing the St. Croix Hastings pellet stove reported that it produced 7,000 – 27,000 BTU per hour.  However, the St. Croix website says the stove produces up 40,000 BTU per hour.  Many manufacturers used to use the BTU input, which is the amount of BTUs available in the fuel, rather than the BTU output from the stove.  But The EPA has been recording estimated and often exaggerated BTU figures on its list of certified stoves for many years and it will be a slow process for them to start recording more accurate BTU figures from new test reports.  The Alliance for Green Heat has urged the EPA to remove all exaggerated BTU data from their list of certified stoves and only post actual BTU output that is determined by an independent lab using an approved calculation.

“The problem with companies using all manner of efficiency and BTU calculations is there is a disincentive to report more accurate numbers that would make your stoves look less efficient and less powerful,” said John Ackerly, President of the Alliance for Green Heat, a consumer focused wood heating non-profit organization.  “The new EPA rules are starting to change what gets posted on its list of certified stoves, but manufacturers can still virtually post whatever they want on their websites and no state or federal agency monitors that, as they do with cars and most consumer appliances,” Ackerly said.

Some companies are beginning to post their lab reports on their websites, so consumers who want extensive technical details can have access to them.  The reports are dense, often long and hard to digest, but can provide useful insights for those who want very detailed, technical information.  Blaze King, Enviro, Kuma and St. Croix were the first to post test lab report for all their stoves.  Jotul and HHT companies Quadrafire, Harman, Vermont Castings, Heat & Glo, Heatilator, Majestic and Eco-Choice now post them as well.   For some companies, such as St Croix, those test lab reports reveal that they have far higher efficiency and BTU numbers in their promotional materials.  Lab reports can also help consumers understand what air settings or power levels their stove is likely to be cleanest, dirtiest, most efficient and least efficient.

Lab reports from testing that was done prior to 2015 usually do not have efficiency numbers or have been whited out.  Some of the posted lab reports are from as early as 1989, are hundreds of pages long and by test labs that no longer exist such as EEMC, Lokee Labs and Northwest Testing.

Advice for consumers:  Beware of efficiency and BTU output claims on websites and promotional literature of wood and pellet stove manufacturers.  The only companies who accurately report their efficiencies on their websites that we are aware of are Blaze King, Kuma and Seraph, Travis and Woodstock Soapstone.  The EPA’s list of certified wood stoves contains more and more actual efficiency numbers and is one of the few reliable places for efficiency information.  Many companies are still holding out disclosing lab reports to consumers.  If you want to be certain you are buying a higher efficiency stove, buy one that discloses their actual efficiency and actual BTU output on the list of EPA certified stoves.  For more information on this topic and a list of stoves that have actual efficiency numbers, check our blog post, A Review of Wood and Pellet Stove Efficiency Ratings.

(This blog will be periodically updated as more data becomes available or if the companies mentioned reply to queries)

A Review of Wood and Pellet Stove Efficiency Ratings; More Manufacturers Posting Verified Efficiencies

As of May 15 2020, all certified wood stoves, boilers and furnaces are required to have a tested efficiency.  This blog discussed the period leading up to May 15, when some heaters had verified efficiencies and others did not.

April 10, 2020 - The number of wood and pellet stoves with verified efficiency numbers on the EPA’s list of certified wood and pellet stoves is soaring as we approach the May 15 deadline, when all stoves in production are required to post their efficiency.  This gives those consumers who really care about verified efficiency numbers many more options. There are now 296 stoves, nearly half of all stoves, that have verified, actual efficiency numbers.  The EPA list of stoves is the definitive source for efficiency numbers as most most stove company websites use exaggerated, misleading efficiencies.

Among the 296 stoves with actual efficiencies, hybrid, catalytic and pellet stoves are the most efficient, averaging 77% efficient for cat stoves and 78% for hybrids.  The average non-catalytic stove is 71% efficient and the average pellet stove 74% efficient.  Pellet stoves also have the greatest range, from 58 to 87% efficiency, a 29 point difference with an average of 74%. Consumers should be aware of which pellet stove they buy.

Consumers should should be especially aware that many stove companies issue Certificates claiming their stoves qualify for the federal tax credit, even though they are far below the required efficiency.  The IRS requires a thermal efficiency rating of 75% but in the absence of any apparent IRS oversight, companies are claiming stoves with efficiencies as low as 59% qualify.  Jotul claims all of their stoves qualify, including their F370 listed at 66% efficiency.  Hearth & Home Technologies claims their Quadra-Fire Classic Bay 1200 qualifies at 63% efficiency.  Neither company replied to AGH inquiries.  The industry association, HPBA, would not comment on how manufacturers should calculate efficiency for the tax credit.

Kuma now holds the distinction of having the highest rated efficiency of any wood stove at 84%, tested with crib wood and the highest tested with cordwood, at 81%.  Enerco, a Cleveland Ohio compnay and ExtraFlame, an Italian company, have the highest rated pellet stove efficiencies at 87%.  Enerco's model, sold under the Cleveland Iron Works label, is a budget model sold in big box stores, as are the PelPro stoves that are above 80% efficiency and have a solid reputation for durability.

The EPA dropped the estimated default efficiency numbers on their list of certified stoves in 2015, an acknowledgement that those default numbers were both inaccurate and not helpful to consumers. (They used to assign 63% efficiency to non-cat stoves, 72% to catalytic and 78% to pellet stoves.) As of 2015, the EPA does not maintain or endorse any efficiency default numbers.

The Alliance cautions consumers against relying on stove efficiency claims posted on manufacturers websites. Most manufacturers post efficiencies numbers using a variety of non-standardized calculations. Virtually all post efficiencies using the European lower heating value (LHV) standard.  A 75% efficient stove using LHV would be about a 70% efficient stove using HHV if the wood was at 20% moisture content. (See this Wikipedia page for more about the difference between LHV and HHV.)

Even if a company has a verified, third party efficiency value on the list of EPA certified wood stoves, many companies will continue to list efficiency values far higher on their own websites, where most consumers get their information.    Only a handful of companies, including Blaze King, Kuma, Seraph, Travis and Woodstock Soapstone, provide the same efficiency number on their website as the independent lab reported to the EPA.  Fewer companies list their official EPA test report on their website next to their product, as required by the EPA.  Exceptions include J.A. Roby, Kuma, and Jotul.  Click here for more on brands that consumers can trust.

The EPA started to require stoves to be tested for efficiency in May of 2015, far later than their European counterparts.   Stoves that were tested and certified before May 2015 did not have to disclose their efficiency until they are required to test again, which will be 2018-2020 for many stoves.  Some of the stoves listed here were done so voluntarily by manufacturers, not because they were required to.  Pellet stove companies in particular appear to be least willing to share verified efficiency numbers with consumers, possibly because their efficiency numbers are lower than the could be.

The EPA began issuing a voluntary hangtag to stoves that meet the 2020 emission standards early, disclose their actual efficiency and meet a variety of other disclosure requirements.  Many of the stoves on the list above will be eligible to display that hangtag on the showroom floor and the Alliance for Green Heat urges consumers to consider buying stoves that display the hangtag.  Stoves sold by Blaze King, Travis and Unforgettable Fire are now approved to display this hangtag and more companies will be approved soon.

How important are efficiency listings?

Tested efficiencies of wood stoves give an indication of how efficient the stove can be when it is operated well with seasoned wood.  Efficiency and emission numbers achieved in a lab under optimum conditions are likely the best numbers that stove can achieve, not an expected average that a consumer will get.

Unseasoned wood that is over 25% moisture content will dramatically lower efficiency.  More important than a 5% difference in tested efficiency is burning your stove with seasoned wood and with enough air to the firebox.  Even the most clean and efficient stove can be polluting and inefficient if it is not operated well.

For pellet stoves, the lab tested efficiency numbers are more representative of efficiencies you get at home, assuming you keep the stove clean.  A dirty pellet stove that has not been serviced for more than 6 months is likely to get lower efficiency.

Wood Stoves with Verified Efficiencies

The non-catalytic stoves on this list range from 60% to 77% efficiency, the narrowest efficiency range of any class of stoves.  Catalytic and hybrid stoves range from 63% to 84% efficiency.  Pellet stoves range from 58% to 87%, the widest efficiency range among different types of stoves.

The Vermont Castings Encore
is a hybrid stove that does not
have a verified efficiency on
the EPA list, but they use one
on their showroom hangtag.

Some companies are claiming verified efficiencies on their showroom hangtags but it is unclear if these are actually verified, HHV numbers.  Vermont Castings, for example, and the hangtag in the showroom shows their purported tested efficiency but they have apparently not provided the a verified efficiency to the EPA for the list of certified stoves.

Pellet Stoves with Verified Efficiencies 

Virtually all companies that make pellet stoves now have some with verified efficiencies on the EPA list, a major shift since May 2015.  Italian company Extraflame currently produces the two most efficient pellet stoves on the EPA list, at 87% and 85%.   Aside from Extraflame, 14 other models have efficiencies above 80%.

The average efficiency of a pellet stoves is about 74% HHV,  but many popular pellet stoves are between 58 and 65% efficient. Of the nearly 170 stoves with actual efficiencies, the only ones under 60% or over 85% are pellet stoves.

For more background on this issue, see:

EPA Begins Listing Actual Stove Efficiencies

The Case for Minimum Efficiency Standards for Stoves

EPA Lists Efficiencies for Outdoor Wood Boilers

4 Reasons Why Wood and Pellet Stove Efficiencies are Usually Unreliable

Misconceptions About Pellet Stove Efficiencies Persist Year after Year

Alliance for Green Heat, Oct. 2, 2013 - For years, scores of websites have been using information from the Department of Energy stating that pellet stoves have efficiency ratings of 78% - 85% and are exempt from EPA emission testing. Many other sites say pellet stoves are exempt from emission testing because they are so clean to start with.  This has been passed down over the years by retailers, the media, industry sites and non-profits.  The only problem is, it’s simply not true.

Pellet stoves are just like wood stoves: emissions regulations were developed to certify them and there are ways to remain exempt from those regulations, including allowing an air to fuel ratio of 35 to 1 or greater.  The classic technology with a huge air to fuel ratio is the fireplace, and its the main reason why fireplaces are so inefficient.  If a wood or pellet stove is exempt because it has a high air to fuel ratio, its also going to be less efficient, but in the case of a pellet stove, it may only be 5 – 20% less efficient, and still in the 50 – 70% efficiency range.

To add to the confusion, the EPA assigned an estimated default efficiency of 78% for pellet stoves, but no one has reminded consumers that the default efficiency only applies to EPA certified stoves, and not the uncertified ones, which are a majority of pellet stoves on the market.  Experts agree that exempt stoves are likely to be less efficient than certified stoves, but no one urges consumers to buy EPA certified pellet stoves to get higher efficiencies, as they do for wood stoves.

Experts in EPA and industry don't even agree if pellet stoves are "exempt" from certification, or just not covered by the rules, even though they have a well-established test method.  Some experts say  that most pellet stoves weren’t EPA certified because they use a loophole to avoid certification, just like some wood stove manufacturers have done.  That loophole allows pellet stoves with excessive airflow to avoid certification.  And that excessive airflow through the combustion chamber and up the stack significantly reduces efficiency.  To complicate things further, many pellet stoves have not tested to be certified, or tested to be exempt.  They are simply on the market and its unclear if they have a 35 to 1 air ratio or not.  

The EPA's Pellet Stove Fact Sheet says, "Technologies are used to ensure the best fuel‐to‐air ratio in the combustion chamber so that the fuel can burn completely". The EPA fact sheet cited HBPA, the industry association brochure as their source.  In fact the opposite is frequently true because EPA regulation allows for far less than optimal fuel to air ratio as a way to avoid certification. 

The DOE page on pellet stoves has lots of great information, but on this critical point, it perpetuates another myth – that pellet stoves are so clean that they don’t need to be certified.  The DOE says, "with combustion efficiencies of 78% to 85%, they are also exempt from EPA smoke-emission testing requirements”.  That myth is being repeated on scores of prominent industry and independent web sites. [Update: As of Oct. 24, the DOE has updated and corrected its website so that it no longer says pellet stoves are exempt.]

Virtually every pellet stove expert agrees that it is unwise to rely on efficiencies posted by manufacturers, because they are not required to test and list efficiencies in the same way and numbers are often not produced by third party testing facilities.  The EPA list of certified wood and pellet stoves has recently started to list actual efficiencies, in addition to the default efficiencies.  Many of issues will be resolved in 18 - 24 months from now, when the EPA will likely start requiring for the first time, third party, consistently measured efficiency numbers on stove labels.  And, the EPA will get rid of the loopholes that allow for uncertified wood and pellet stoves to be sold on the market.

Consumers are also provided exaggerated efficiency numbers by many if not most pellet stove manufacturers because they report using LHV numbers, instead of HHV ones, but they don’t tell the consumer that they use LHV.

The DOE and EPA should do far more to encourage people to switch from wood to pellet stoves because they are consistently much cleaner and a very effective way to drastically reduce fossil fuels.  They should also help consumers understand what stoves the default efficiencies apply to, and why others can be exempt from certification.  In the meantime, consumers should consider buying EPA certified pellet stoves if they want to ensure higher efficiency stove, whether it is wood or pellet.

Virtually every fuel calculator lists pellet stoves at 78% efficiency without telling them that this only applies to EPA certified pellet stoves.  The average pellet stove is probably around 70% efficient, and could even be lower than the average of EPA certified wood stoves.  Using fuel calculators to see how much you can save switching from fossil fuel to pellets is difficult if you can't get a reliable thrid-party efficiency rating on a pellet stove.  No one knows how many consumers unwittingly bought pellet stoves that may not even be 60% efficient. 

For more consumer information on how to select an efficient stove, click here.

Verified Pellet Stove Efficiency Key to Industry Success

The pellet industry has been developing certification standards to ensure that consumers know the quality of the pellets they are buying, but a similar issue is being overlooked when it comes to the equipment that uses the pellets—the efficiency of the stoves.

There is virtually no credible information available to consumers that indicates which stoves are extremely efficient, and which are pellet guzzlers. The federal and state governments should be clamoring for this information, because pellet stoves and boilers are the biomass heating appliance that most deserves incentives, and incentives are almost always tied to efficiency.

For full story, click here.