AGH urges the IRS to issue guidance on wood heater eligibility for tax credits

Thank you for this opportunity to provide comments.  IRS guidance on wood heaters is long overdue.  The Alliance is an independent non-profit organization that strives to represent the interests of consumers of wood and pellet heaters.  We believe a tax credit for wood and pellet heaters is essential as we transition from fossil fuel to renewable fuels. 

The IRS asked whether guidance needed to define the term "thermal efficiency rating"? If so, what testing procedures should the Treasury Department and the IRS consider requiring or permitting to be used by manufacturers to measure thermal efficiency and demonstrate ratings that are valid for purposes of the § 25C credit?

 

Summary: The most reliable method to protect consumers, ensure that tax credits are going to compliant models and create a level playing field for manufacturers is for Treasury/IRS to specify that eligibility is limited to units listed in the EPA Certified Wood Stove Database that have an overall weighted average efficiency of 75% or more using the higher heating value of the fuel.  

 

Using the EPA database to determine eligibility is the most effective solution from a variety of public policy perspectives but it is not without problems: multiple test methods result in disparate EPA seasonal average efficiency results for wood and pellet boilers, which are not comparable, and which are not helpful for consumers or for the purposes of setting an efficiency threshold for the tax credit.  The EPA is aware of the problem but an impending change in IRS guidance on wood heater tax credits is likely to hurt members of the industry who sell some of the most sophisticated modern wood heating equipment.  We urge the IRS to consult with the EPA on this problem and find a solution as soon as possible.

 

In addition, we urge the IRS to make it clear that the $2,000 tax credit for wood heaters is in addition to the $1,200 for other 25C qualifying home projects, not instead of them. The IRS should clarify that the full $3,200 is available to taxpayers. We also urge the IRS to confirm that 25C tax credits are available to renters, not just to owners of residences, based on the removal of the term “owner” by Congress.

Finally, the IRS asked for comments on certification or other requirements for home energy auditors.  We urge the IRS to affirm that when energy auditors are directed to inspect HVAC systems, that wood and pellet heaters are recognized as legitimate heating devices and need to be inspected for safety based on nationally recognized criteria, just as other heating systems are.  Various agencies and institutions such as DOE, NREL and BPI have begun to address this problem but wood heater remain marginalized, leaving many older, self-installed units that pose fire hazards and are not being properly inspected.

Background on wood and pellet heater testing: There is universal acceptance among test labs and manufacturers that efficiency is measured using in accordance with CSA B415.1-10.  When stoves are tested for EPA certification, the traditional test is to use the EPA’s “Method 28” which consists of 4 burn rates, from low (Category 1) to high (Category 4).  The lowest burn rate allows the lowest amount of air to flow through the stove and typically produces a higher efficiency.  High burn rates allow maximum airflow through the stove, and typically produce lower efficiencies.  The labs then combine these 4 efficiency numbers and produce “a weighted average efficiency” which is what is recorded on the EPA database of certified heaters as “overall efficiency.”

CSA B415 produces three types of efficiency: Overall efficiency, combustion efficiency and thermal efficiency.  The EPA uses Overall Efficiency to get an Average Overall Efficiency” and EPA guidance on testing deficiencies makes no reference to “thermal efficiency.”  Even within the wood and pellet heater industry, there is confusion between the terms “overall efficiency,” “thermal efficiency” and “weighted average efficiency.” The image below is an representative example of how test labs report efficiencies.  

Each of the four burn rates produces an overall efficiency number, and combustion efficiency number and heat transfer, or thermal efficiency number.  The EPA averages the four overall heating efficiency numbers to get a weighted average efficiency.  In the EPA database, this weighted average efficiency is in the column titled “Overall efficiency- HHV.” (The EPA used to use the term “Actual measured efficiency CSA B415.1 after they stopped using default, estimated efficiencies in 2015.)

There are eight labs approved by the EPA to conduct certification testing, including one in Canada, Czech Republic, Denmark and Sweden.  The labs do not use efficiency terminology consistently, and often just refer to “efficiency” rather than “overall efficiency” or “weighted average efficiency” rather than “weighted average overall efficiency.” All labs clearly distinguish HHV and LHV, and no lab uses “thermal efficiency” in their weighted averages, as far as we know.

However, some manufacturers will use “Heat transfer efficiency” otherwise known as “thermal efficiency” numbers to qualify models for the tax credit because they tend to be 1-2% higher than “overall efficiency.” Thus, if a stove has an average overall efficiency of 75%, it could have a single burn rate as low as 69%, using thermal efficiency numbers.  No manufacturer uses combustion efficiency for purposes of the tax credit as far as we know.  Combustion efficiencies tend to be in the 96-98% range.

Wood heaters are tested by EPA approved labs and then the EPA uses the data in the report to certify the stove for sale. Once it’s certified the EPA puts summary data on its Database of certified wood heaters. Since 2015, the EPA has also required manufacturers to post the non-confidential parts of their lab test report on their website.  Those reports are public and you can find the efficiency numbers for each burn rate, but they are not easy for consumers to navigate. On the contrary, they are dense, full of fine, highly technical jargon and are only used by regulators and experts.

Statistics: Currently, 25 of the 31 central wood heaters are eligible for the tax credit, using the EPA list.  113 of the 262 room heaters are above 75%, using the EPA list.  Overall, that would make about half of all heaters eligible, if the IRS were to use the efficiencies listed on the EPA database.

Public policy considerations: To achieve a level of transparency for the consumer, using the EPA database of certified heaters is an obvious solution.  Some consumers care about efficiency and the only place that consumers can make side-to-side comparisons is on the EPA database.  With pellet stoves, efficiency typically matters more than wood stoves because unlike cordwood, all pellets must be purchased, and a more efficient stove can save consumers by using less fuel.

If the IRS wants to be more lenient with manufacturers and allow more than about half of heaters to qualify, it could keep allowing manufacturers to issue certificates without any guidance, or specifically say that if any burn rate achieves 75% efficiency or more, it can be eligible for the tax credit.  If the IRS specified this, we expect all manufacturers would quickly adopt this system and about 80% or more of appliances would be deemed eligible.

Public policy is also served by setting a level playing field for all manufacturers, instead of allowing some brands to undercut others by claiming their units are eligible for the tax credit when they are below 75% on the EPA database.  Almost all US manufactures now use the EPA database to determine if their models are eligible.  

By setting an efficiency threshold for wood heaters, certain types of wood heater benefit.  The Alliance for Green Heat has monitored the changes to efficiency in wood heater for more than 10 years and documented the various ways that manufacturers claim that their stoves are eligible for the tax credit.  The averages below were calculated several years ago, when efficiencies were lower but the conclusion is remains the same: hybrid wood stoves have on average, the highest efficiencies are virtually all of them qualify for the tax credit, under any definition.  More manufacturers are building hybrid stoves in order to qualify for the tax credit and whereas there were only 6 models several years ago, today there are at least 21. Non-catalytic stoves, the cheapest, most popular, and most basic stove, have the hardest time reaching 75% efficiency. Today, only 15 out of 113 non-catalytic models are 75% or over.

From a public policy perspective, setting a 75% efficiency minimum, using the EPA database of certified heaters, is positive in that it tends to favor stoves that emit fewer particulate matters (PM) emissions.  Non-catalytic stoves tend to have higher emissions both in the lab and in the hands of homeowners if other factors are equalized such as moisture content of wood and ability of the operator. Pellet stoves and hybrid stoves tend to the cleanest, as used by homeowners.

Many taxpayers want to be able to download a certificate of eligibility to keep in their files, and taking a screen shot of the EPA list may not be as easy or feel as secure. The owner’s manual of the stove almost always has the weighted average efficiency, so that can also serve as proof of eligibility for the taxpayer.

There are two classes of heaters that would be unfairly penalized by an IRS requirement to base eligibility off the efficiency numbers in the EPA database.  The first is that multiple test methods result in disparate EPA seasonal average efficiency results for some indoor wood and pellet boilers which are abnormally low and are not comparable to other boilers or helpful for consumers or for the purposes of setting an efficiency threshold for the tax credit.  The EPA is aware of the problem, as is NESCAUM and NYSDERDA who are involved in testing programs to try to identify the calculations and assumptions leading to this problem and then find a solution.

The second are Masonry heaters are also penalized but since they do not yet have a pathway to EPA certification, the solution is more complicated. There are consistent and reliable ways to test factory-built masonry heaters and those manufacturers could issue Certificates of eligibility for the tax credit, but they will not be listed on the EPA database.  Standard combustion chambers used in site-built masonry heaters could also be tested but this is more complicated.  The Masonry Heater Association is the point group on this issue.

IRS options

The IRS has several options, depending on what their goals are.  

 

1.     The first, and best option, in our opinion is to use the “overall efficiency” numbers listed on the EPA database of certified wood heaters be the sole arbiter and end the practice of using manufacturer certificates, or only allow manufactures to issue certificates for heater models that are listed at 75% efficiency or higher on the EPA database. Many of the benefits of this are discussed above in the public policy discussion.

 

2.     There is a hybrid option of allowing manufacturers to issue certificates of eligibility if a model exceeds is 75% efficient or over for stoves and outdoor boilers or furnaces, or is 75% or more overall efficiency on any of their burn rates for indoor boilers or furnaces. 

 

3.     There is the current system, where manufacturers self-issue a certificate to declare that a particular model is eligible, sometimes without any reference to efficiency figures or definitions. This has resulted in manufacturers claiming models with weighted average efficiencies as low as 64% to be eligible. This has also allowed manufacturers to claim units that are not EPA certified to be eligible without providing any efficiency data. Another weakness of this option is that there is no agency with the time, resources, or agility to provide enforcement in this area, leaving consumers vulnerable to false claims. 

 

On the following pages, we have included representative samples of four types of manufacture certificates of eligibility for the tax credit.  The disparity of the language used and the range of models that are claimed to be eligible for the credit show a clear need for more guidance for the IRS.

 

A. Example of a certificate that claims eligibility without reference to efficiency, even though it appears all units are above 75% efficiency based on the EPA database.

 

B. Example of a company that claims its units are eligible, even though they are well below 75% on the EPA list and do not meet 75% even on individual burn rates.

 

C. Example of EPA non-certified stoves without EPA approved third party lab efficiency data to claim eligibility.

 

D. Example of a certificate that claims models are eligible solely because they are “qualified energy property” with no reference to efficiency.

 

Gas stoves and fireplaces appliances need better regulation and transparent efficiencies

Public comment from the Alliance for Green Heat 

April 8, 2022

RE: Docket Number EERE-2021-BT-DET-0034: Notice of Proposed Determination of Miscellaneous Gas Products as a Covered Consumer Product

Thank you for the opportunity to comment on miscellaneous gas products as a covered consumer product. 87 Fed. Reg. 6786 (February 7, 2022).

In the United States, efficiencies of gas stoves are often unavailable, and it can be very confusing. The only reliable database is maintained by the Canadian government and consumers often do not know to check it, even if they want a more efficient appliance. Consumers who are trying to save on heating bills often use their gas stove or fireplace to heat the core of the house instead of using the gas furnace to heat entire house. Gas furnaces can waste up to 30% of their heat from leaking ducts. According to the DOE, “Ducts that leak heated air into unheated spaces can add hundreds of dollars a year to your heating ... bills."

We found that very few websites provide accurate information about gas appliances for consumers, in part because there are many gray areas due to lack of regulation. The CEO of one US manufacturer of gas stoves that we spoke to did not know if was required to test for efficiency or even if his products had been tested even though they were designed and marketed as heaters. We also called many retailers and received a wide mix of contradictory information. One told us we had to ask the manufacturer about efficiency. One had no idea how to determine efficiency. And one provided an efficiency from the “nameplate” but when we checked that number with the Canadian database, it was different. We concluded that consumers should beware of efficiency claims on manufacturer websites or from retailers and to always check the Canadian database if they wanted to know the efficiency of a product.

As a result of this, we strongly support the DOE finding that decorative hearths and outdoor heaters qualify as covered products under EPCA. Gas fireplaces and stoves are often used daily to provide heat for homes, as both a primary and secondary heat source. Consumers stand to save significant amounts of money and gas if these heaters are regulated and have to meet minimum efficiency standards. Many retailers advertise that gas inserts can easily serve as the primary source of heat for your home and claim that they use “50% to 90% less gas than gas logs and up to 75% less gas than a gas furnace.”3

Advertisements often
tout the heating benefits
of gas over wood in a
variety of ways.

We also support DOE’s determination to include propane products in the scope of this proposed coverage determination for miscellaneous gas products. Stoves and fireplaces that use propane are nearly identical to those that use natural gas and are very popular in areas that are not served by gas pipelines. The same companies that make gas appliances also make propane ones and it makes little sense to regulate one and not another and would create a confusing and artificial distinction for manufacturers, retailers and consumers. Propane is typically even more expensive than natural gas, so consumers stand to save far more if they have transparent and minimum efficiency ratings.

We are concerned that DOE may have underestimating the annual shipments of miscellaneous gas products. To the extent the DOE relied on figures from HPBA, they must consider that HPBA shipment data typically only includes appliance shipments by their member companies, not by all companies that make and ship gas appliances. In recent years, some of the largest gas appliance manufacturers have dropped their membership in HPBA, and as a result, shipments from those companies would probably not be included. HPBA does not disclose which companies provided data and which didn’t. Even for member companies, they cannot require disclosure of shipment data, but it appears member companies usually participate.

Thank you. Sincerely,

John Ackerly
President
Alliance for Green Heat

Non-cats cleaner than catalytic or pellet stoves in new certifications

In the most recent updated list of EPA certified stoves, 17 more units became 2020 compliant, meeting the 2020 EPA regulations of emitting no more than 2 grams an hour.  While it is not a large sample size, among this batch of newly certified units,  the non-catalytic stoves averaged 1.2 grams an hour, whereas catalytic stove averaged 1.3 and pellet stoves averaged 1.4.  It is not yet clear if the non-catalytic stove designers used new innovative technology or just fine-tuned existing strategies to reduce particulate matter.

Of the 17 newly certified stoves,
non-catalytic models are the cleanest

Many industry experts have argued that the 2020 emission standard of 2 grams an hour favors catalytic and pellet stoves.  But we are seeing some non-cats come in below 1 gram an hour, including 2 of the 5 in this recently certified batch.  Many of the 2020 compliant non-cats do fall in the 1.5 to 2 gram range.  And every once in a while, a stove goes into the lab and doesn't quite meet the 2.0 gram standard, like a IHP stove that recently came out certified at 2.1 grams.  Assuming this unit was not tested with cordwood (which are allowed up to 2.5 grams per hour), this means that the model can only remain on the market in the US for less than 18 months until May 2020, unless the EPA were to approve a sell-through.

Efficiency

The average efficiencies show a less surprising trend: the 13 newly certified non-catalytic and pellet stoves had the same average efficiency – 69%.  The four catalytic stoves, including one hybrid, had an average of 77% efficiency.  These efficiency numbers are typical of averages of all stoves on the market. Pellet stoves have long had the reputation of being a more efficient technology, but over the last several years, as manufacturers were required to disclose efficiencies,  we saw that pellet stoves had a far greater range on the low and high end, with the average being about the same as non-cats.  Even among this small sample, pellet stoves had the lowest efficiency unit (at 60%) made by Sherwood Industries.  Sherwood also made the highest efficiency pellet stove in this newly certified batch – at 77%.

Efficiency could be a more important metric if Congress re-instates the tax credit for residential wood heaters.  That credit was worth $300 but expired in December 2017.  Stoves needed to be 75% efficient to qualify for the tax credit, but manufacturers were allowed to claim eligibility without disclosing their real efficiency, allowing virtually all stoves to qualify.  The practice of exaggerating efficiencies and misleading consumers got to the point that even the industry association, the Hearth Patio & Barbecue Association, changed course in 2018 and recommended that only publicly disclosed efficiencies on the EPA list of stoves be used in the future to determine eligibility.  If the credit is reinstated, there is a chance that the eligibility number could be reduced to 73%, in part to help more non-catalytic stoves qualify.

Carbon monoxide

The other metric that test labs are now required to report is carbon monoxide, another very important test of cleanliness, along with particulate matter.  By far the cleanest technology in terms of CO is the pellet stove. The pellet stoves in this small batch had an average of 0.42. grams an hour of CO, the catalytic had 0.63 grams and non-catalytic stoves had 1.2 grams – almost double the CO of non-cats and triple that of pellet stoves.

A stove's ability to burn off carbon monoxide often tracks its ability to burn off particulate matter.  Of the pellet stoves, the three with the lowest CO also had a lower average PM (1.2 grams an hour), and the three with higher CO had a higher average PM (1.5 grams an hour).  

Overall progress towards 2020

There are 533 stove models on the latest list of EPA certified stoves that are currently in production.  Many of those units will never be changed to become 2020 compliant and many are already not being produced any more.  Industry experts say that the number of stove models will contract as we get closer to 2020, likely in the range of 300 – 400 models.  As of February 2019, 119 models are 2020 compliant.  (The number of 2020 compliant models is consistently under-reported due to delays in processing and notification.)  Many manufacturers may also have completed their R&D and/or their testing but have not submitted the data to the EPA. 

Most stove manufacturers have at least a third to half of their models 2020 certified – including larger brands such as American Energy Systems, Blaze King, Even Temp, Fireplace Products International, Hearthstone, Pacific Energy, Rais, Ravelli, RSF/ICC, Sherwood Industries, Stuv, Travis and Woodstock Soapstone.

However, the two largest value stove manufacturers in the US market – US Stove and Englander – only have pellet stoves certified and still do not have any 2020 compliant wood stoves.   They sell to big box stores, which buy even earlier than specialty retailers.  It is still too early to tell if big box stores will replace Englander and US Stove models with models from other manufacturers, likely at higher prices.  Some in industry hope that the 2020 emission standards will help specialty heath stores regain some of the market share they had lost to the big box stores over the past decade.  

Meet the Teams: A father-son forge an entirely new breed of hybrid wood/pellet stoves

This post is the third in a series introducing the 12 teams participating in the 2018 Wood Stove Design Challenge in November.

By John Ackerly and Shoshana Rybeck, Alliance for Green Heat 

Dusty and his father with their stove. 

The stove is so novel that the EPA can’t figure out whether to call it a wood stove or a pellet stove. That’s because it’s neither—or both—depending on how you look at it.

The stove burns logs that are pressed out of sawdust. The logs are automatically fed by a gravity system one after the other. There is no auger, which all pellet stoves have, but the stove achieves consistently high efficiency and low emissions that no wood stove can get. It's the first one of its kind on the market, and the EPA and the entire stove industry doesn’t quite know what to call it yet.

This father-son run business team got into the industry after years of admiring the work of Frank Reed of Hayden, ID, a long time friend of the family. Reed first designed the stove on a dare in 2010 to prove that you can run a stove by burning a single log at a time. The stove had been heating his shop for 7 years. The son of the team, Dusty Henderson, kept asking Reed what he was planning on doing with the innovative design. Reed responded “nothing.” Dusty and his father then bought and patented the design, convinced that it was marketable and could fill an important gap in the residential wood and pellet stove market. 

With an educational background in criminal justice, Dusty would seem to be an unlikely entrepreneur to bring a novel stove to market. However, Dusty recalls being “mechanically inclined” from a young age and he always wanted to bring a product of his hard work to the marketplace. Dusty’s entrepreneurial drive along with his shared hobbies with his father first brought them to work together right after Dusty graduated college, when they began a contracting business together. Now, more than twenty five years later, Dusty and his father have developed Reed’s design, of which they have complete ownership.

Dusty says that they are committed to building such a high quality product that it should be a once in a lifetime purchase. They built the stove with premium parts, which are coated in quality paint with “no burn off whatsoever, smells, or off gasses.”

A different type of animal

509 Fabrication’s stove is unlike any other on the market in that it runs on compressed logs rather than cordwood or pellets. The stove, called the Optimum, continues to be classified as a pellet stove by the EPA, a strange designation since consumers are not allowed to burn pellets in it.  The EPA is increasingly focused on ensuring that stoves be advertised only to burn the fuel that they were tested with, as part of a renewed education effort. “Listing us as a pellet stove is not good for our business and we don’t want the EPA creating confusion about our product—which is already unique enough,” Dusty said. 

Final model of the stove heating
the showroom.

The Optimum burns one compressed log at a time, seamlessly from one end to another, and can be loaded with 3 logs at a time. Unlike a pellet stove, where the operator can adjust the amount of fuel going into the burn pot, the Optimum is adjusted solely by the amount of air getting to the fuel. Heat settings are controlled through the simple opening and closing of the air valve. 

Dusty and his father had to experiment with feed tubes and the early models used feed tubes at an angle, instead of vertically as they do now. The vertical feed tube allows for “more room to add heat exchangers” and ensures consistently high efficiencies at all burn rates. Getting the right amount of combustion air at each of the 3 heat settings was perhaps the biggest challenge. “A big issue was  finding the right fuel to air ratio, and then figuring out how to get that air to the right places,” Dusty said.  

This is one of the stoves competing in the 2018 Wood Stove Design Challenge that is already certified and on the market and thus has third party testing data available. The Optimum was certified at 1.5 grams of PM per hour and 78.8% efficiency and they post their lab report (pdf) on their website as required by the EPA, unlike some companies that still don't do that.  The report shows emission and efficiency levels at different heat setting and the Optimum may be the first wood or pellet stove to have such a high, steady efficiency, ranging between 77.2% and 79.5% on 6 test runs.

However, Dusty and his father went through many different prototypes until they landed on the final model shown above. The team constantly altered the models pre- and post-testing to improve efficiency, reliability, and overall quality. Below are a couple of the old prototypes that were ultimately changed to create the Optimum we see today. 

Early prototypes 

The Fuel

Dusty has seen the compressed log industry grow throughout the years. It continues to spread, even to far flung places like Alaska where cities and communities are battling excessive wood smoke and pressed logs could be a valuable fuel to help reduce emissions. The stove can be used with pressed logs made by a variety of companies across the US, including North Idaho Energy Logs, Lignetics in Sandpoint, ID, Home Fired Logs in Ferndale, WA, and Superior Pellet Fuels in North Pole, AK. What cannot be used in the stove are logs made with wax or coffee grounds. Those products typically emit far greater emissions and will clog up the Optimum and are often far more expensive than natural pressed logs, which like pellets, have no additives whatsoever.  Pressed logs and wood bricks are the same product in a different shape and they often cost about as much as cordwood when measured by BTUs that go into the house. Cordwood is much cheaper by volume but is much less dense, and cord wood stoves usually only get between 60-70% efficiency.

From the Challenge to the market 

509 Fabrications is currently looking to expand their market penetration, a common goal for most stove manufacturers. Many stove dealers have non-compete agreements where they cannot sell other brands of pellet stoves, but these would not apply to the Optimum. The company is also looking for more recognition from change out and incentive programs, as their hybrid stove may appeal to people who have burned cord wood, while putting out consistently low PM like a pellet stove.

Final model of the Optimum stove

 ready for shipment.

At the Design Challenge in November the stove will be tested again to see if it can meet—or exceed—the emissions and efficiency of other stoves in the competition. All of its other features and controls will also be assessed by a team of independent experts. Only a few stoves will win awards at the event and all will be ranked against one another.  

Click here to learn more about 509 Fabrications and the Optimum. 

Connect with the team

Dusty Henderson 

dusty@509fab.com

Meet the Teams: Canada’s largest stove company looks to the future in automated stoves

This post is the third in a series introducing the 12 teams participating in the 2018 Wood Stove Design Challenge in November.

By John Ackerly and Shoshana Rybeck, Alliance for Green Heat 

The SBI team 

Stove Builder International (SBI) built the innovative Osburn Volta pellet stove in 2012 and made important strides in understanding how sensors can control combustion. The Volta is unique in that it runs on direct current (DC) when all other pellet stoves run on the normal household AC current. The Volta has its own battery pack and can be easily integrated with solar power.

After seeing the announcement for the first Wood Stove Design Challenge, SBI knew that it could convert skills and lessons from the Volta to an automated cord wood stove. Their prototype was not ready for that competition, but lead engineer Nicolas Gagnon attended the 2013 event and was excited by what he saw.

Guillaume Thibodeau-Fortin, an SBI mechanical engineer, believes that wood stove automation is likely to be one of the main trends in stove manufacturing in the future. But finding the time and resources for the R&D was tricky. Guillaume started working at SBI in 2013 and knows that stove buyers are price conscious and they need to see far more value in an innovative stove than its ability to burn clean.

SBI’s location in Quebec, the French speaking part of Canada, gives them more insight and interaction with the European stove market where small, vertical stoves are more popular and where more companies are experimenting with automation. SBI’s headquarters is also not far from Montreal, North America’s largest urban area experiencing severe wood smoke issues. If there is any major North American city that needs a cord wood stove that can run reliably clean in the hands of consumers, it's Montreal.

“So we designed this for multiple reasons—not just to build a stove that operates cleanly in our customer's home. Automation also serves to improve safety, efficiency and ease of use,” Guillaume said.

The Technology

The stove is built on two radically new ideas. The first is that the stove automatically finds the optimum combustion conditions. That is a core goal of all modern combustion, whether it’s in a car, a power plant, or now, a wood stove. The second is connecting that stove to the operator to engage, inform and educate the operator to better perform his or her roles.

Final model of the stove

A key problem with appliances that need periodic operating adjustments is educating the owner. Printed owner's manuals are often not good education tools, even when they are read and reread by the operator. The SBI stove is connected via Wi-Fi to a smart phone, and Guillaume’s vision is to transfer the old fashioned owner’s manual into a far more appealing, usable and effective interface on the phone. The stove can alert the operator when it’s time to reload for example, and instructions will appear that can include a link to a video about how to tell if your wood is dry.

To automate the stove, the first step was attaching a temperature sensor, but the key was to correlate data from the thermocouple with a static pressure sensor. Utilizing an oxygen sensor could have been better but the pressure of keeping down costs steered the team away from that strategy. The team then turned to computational fluid dynamics to track and predict gas activity in the firebox. 

Efficiency and particulate matter emissions are focal points of progress for wood stove design. With better efficiency, PM is usually reduced as combustion is more complete and therefore cleaner by nature. However, the opposite condition is not necessarily true, as emissions can be reduced by adding oxygen which ultimately penalizes efficiency. SBI is paying closer attention to efficiency, which many stove manufacturers did not do in the past, but ultimately, it’s the PM level that determines if a stove can go to market.  

Electronic board in the stove

SBI’s model for increased efficiency relies on sophisticated control of the primary air inlet and a digital user interface that is connected through Wi-Fi on the user’s mobile device. The stove includes three burn rates, low, medium, and high, and is set to each level via a mobile application. To achieve the user-set burn rate, the automatic stove then takes over, using temperature and static pressure sensors to open and close the air inlets and run a motor that adds primary air in or blocks it out depending on how high combustion is and what level the user would like. While the user has control over the desired heat output, the user does not actually have the ability to change the stove's air flow to raise or lower the burn rate mechanically. The inlet for the primary air cannot be opened or closed by the operator, unless the stove is running cleanly, and if so, the stove will respond in real time to the operator’s changes. If the stove is not burning cleanly, it will first get to a cleaner burn before getting to the desired heat output set by the operator.

Setting the heat level from the comfort of your couch via their mobile device should appeal to many customers. Knowing that you don’t have to periodically check to see whether you have given the stove too much or too little air should give everyone in the house more peace of mind. If the main person who operates the stove is out, the person who adjusts the stove doesn’t have to worry about over firing, making stove smolder, or putting out the fire. The internal temperature and static pressure sensors will bring the stove to the desired heat level in the safest and cleanest manner. 

When we spoke to the President of SBI, Marc-Antoine Cantin, about the development of an automated stove at the HPBA Expo in Nashville, we were struck with how hands off he was with the R&D process on the automated stove. He gave Guillaume and his team the autonomy and support to go through the multi-year process of developing a stove that the company can stand behind. To us, this indicated a company that is big enough to support engineers working on tangential, forward looking projects and an engineering team that has built the trust of management.  

While introducing an efficient, and user-friendly automated wood stove to the market is important, SBI understands that people are first and foremost looking for an affordable and reliable form of renewable heat. When designing and creating their model, the concept of affordability was always key. One of the three head engineers on the project said, “keeping it simple is best for efficiency and the bank.” For them, the 2018 Wood Stove Challenge is giving them the platform to challenge their engineering skills in order to prepare for a cleaner wood burning future.

Contact the team

Guillaume Thibodeau-Fortin
gthibodeaufortin@sbi-international.com

Maxime Legros
mlegros@sbi-international.com

Nicolas Gagnon
ngagnon@sbi-international.com

Six tips to buy the right pellet stove

Retailers say BTU output can be most confusing issue

Glenn Robinson is one
of many retailers struggling
to help consumers avoid
relying on manufacturer
claims about BTU output.

Updated on Jan, 7, 2021 - Glenn Robinson has been selling and installing pellet, wood and coal stoves in Pennsylvania for 11 years, and one of the biggest problems he faces is sizing the stove.  “I became tired of false information from manufacturers about how many BTUs they claimed their stoves put out” he said in a recent interview.  “Customers see these exaggerated BTU numbers from a small stove and think it will heat their home, but it won’t.  The result is that the stove is undersized and there is premature wear and tear.  One model from a big name brand would only last for 3 – 4 months before needing repair or even full replacement,” he said.

Glenn is not alone in identifying exaggerated BTU listings as one of the biggest problems consumers face in buying a stove.  Scott Williamson, a Massachusetts pellet installation and repair technician says that he sees stoves “all the time that are being run on high 24/7 and pellet stoves just aren’t designed to do that.”  Both installers say that under sizing of pellet stoves is one of the biggest problems, and urge customers to consider larger (higher BTU output) stoves if they live in average size homes in the northern half of the country and plan to use the stove a lot.

Buying a pellet stove can be a confusing process for consumers (but as of 2021 high efficiency pellet stoves and installation costs are eligible for a 26% federal tax credit!)  Retailers are likely to push the brands they sell and manufacturer websites don’t tell the whole story.  Objective, third party reviews are rare and often outdated.  Consumer Reports did a pretty good review in 2009 but used very limited criteria and didn’t test for durability.  The Alliance for Green Heat (AGH) also undertook third party testing in 2015 and issued a detailed online report on some issues including BTU output, maintenance and efficiency. (Like Consumer Reports, AGH conducted completely independent testing by purchasing all the units and doing all of our own testing.)

This blog identifies and discusses six rules for consumers to keep in mind when buying a pellet stove, with a focus on sizing.  This is not an exhaustive list but it’s a good place to start: 1. Don’t undersize, 2. Beware of cheaper stoves, 3. Look for range of heat output, 4. Understand maintenance requirements of the stove, 5. Look for cleaner stoves and 6. Beware of stoves with no efficiency on the EPA list

AGH tested six popular pellet stoves.
Almost all performed well during
intensive 30 day testing, but did not
live up to some manufacturer claims.

Pellet stoves can be a very effective and affordable way to provide primary or secondary heat for your home without the smoke that wood stoves often create in the hands of the typical user. Wood stoves require lots of work on the fuel side of the equation, but pellet stoves involve more work on the appliance side of the equation. 

The Alliance for Green Heat also monitors advertising of pellet stoves and has found over the years that the great majority of companies vastly overrate the amount of heat their stoves put out.  The EPA list of certified wood and pellet stoves is not perfect but it remains the best source of BTU output for consumers. 

Most EPA-certified pellet stoves are listed as producing a maximum of 25,000 – 40,000 Btu and minimum of 7,000 – 13,000 Btu. The average pellet stove on the EPA list, according to data provided by third party test labs, put out a maximum of approximately 31,800 Btu and a minimum of approximately 10,050 Btu. 

The stove with the highest maximum Btu on the EPA list is the Harman P68 at 53,500 Btu (advertised at 71,200 Btu input).  When a stove manufacturer lists Btu input, it refers to amount of Btus in the fuel, if you were to get 100% of those Btus into the room.  But the average pellet stove is around 73% efficiency, which means you will get 73% of the fuel’s potential heat into the room.  (This is similar to the AFUE – the annual fuel utilization efficiency – that is used on gas and oil boilers and furnaces.)

The stove with the lowest maximum Btu is the Thelin Gnome pellet stove that puts out up to 9,000 Btus.  However the company advertises three times that - 27,000 Btus - without any explanation.  Manufacturers usually exaggerate Btu, thinking that it will make their stoves more attractive, but in the case of the Thelin Gnome, there are people looking for stoves to heat very small places and the exaggerated Btu output may make them think even the Gnome is too big.

Here are six critical things for consumers to keep in mind when purchasing a pellet stove:

1.       1. Don’t undersize. If the stove is going to be your primary heat source you will likely need a medium or large pellet stove, even if a smaller unit advertises high BTU output.  Ignore BTU numbers on manufacturers websites and literature and check the EPA list.  The maximum output for pellet stoves is in the 30,000 – 50,000 range, enough to heat all or most of a small or medium house in most climates. “Don’t plan to run the stove all the time at its highest setting,” warns Scott Williamson “or you will be calling someone like me to fix it quicker than you think.”  When we tested six popular pellet stove models, we calculated an output of no more than 21,000 BTUs, far below what the EPA listed and even farther below what manufacturers claimed.

It is possible to oversize the stove and that can be a problem, but is not nearly as common as under sizing.  “For example, the Harman P68 is notorious for being installed in small areas like mobile homes but they gunk up when they aren't allowed to get up to temperature for a bit before they shutdown,” says Scott Williamson.

2.      2. Beware of cheaper stoves. There are some good budget wood stoves on the market, but with pellet stoves, you are more likely to get what you pay for than with wood stoves.  “If you want a reliable stove that puts out a lot of heat, we urge customers to ignore pellet stoves under $2,500,” says Glenn Robinson.  Scott Williamson generally agrees but has seen some basic stoves like the Pel Pro in particular holds up very well.

3.      3. Check for range of heat output.  Most stoves can put out about 3.5 times more heat at their highest setting, compared to their lowest.  Some stoves have a tiny range, putting out only 1.5 times more heat at their highest setting.  If you live in a more moderate climate, in the early fall and late spring, you may want just a little heat, and still have the capacity for much greater heat output on the coldest days and nights of winter.  All other things being equal in a stove, you may want a stove with a larger range of heat output and you can check the range of all stoves on the EPA list of certified stoves. In our tests, we found that the Enviro M55 insert ran continuously for an impressive 49 hours on its lowest setting with a tested hopper size of 60 pounds and it ran for 22 hours on its higher setting.  However, with a 37-pound hopper, the Englander 25 PDVC only rain for 15 hours on its lower setting and 13 hours on its highest setting, indicating a very low turn down ratio.

4.       4. Understand maintenance requirements. If you don’t clean your stove regularly and have it professionally serviced once a year, don’t expect high BTU output.  Most consumers get subpar performance from stoves and have to repair them more often because they are not maintaining their stoves according to the owner’s manual.  Pellet stoves are not like wood stoves: they have lots of moving parts and need cleaning of the burn pot and inside the stove on weekly, and depending on the stove, a daily basis.  Pellet stoves that are not cleaned regularly can lose 10% or more of their efficiency – and their heat output, and lead to costlier repairs. Understand the daily, weekly and annual maintenance requirements from the start and don’t put them off.  When we tested six popular pellet stoves, we found that the three more expensive ones (Harman, Quadra-Fire and Enviro) could go for a week or more without cleaning the burn pot.  However, the Englander, Ravelli and Piazzetta needed daily burn pot cleanings.

5.       5. Look for cleaner pellet stoves and ones that are 2020 certified.  Pellet stoves are far cleaner than wood stoves, even if they both have the same particulate matter in grams per hour.  Particulate matter is the tiny stuff that smoke is made out of and pellet stoves should not have any visible smoke after the 3-minute start up.   The average pellet stove used to put out about 2 grams of particulate per hour.  But since the new EPA regulations took effect in 2015, pellet stoves have become even cleaner and more efficient.  As of April 2020, more than half of the 2020 certified pellets stoves emit 1 gram or less per hour. This makes pellet stoves more suitable in more densely populated suburban and even urban areas.  Choosing a cleaner pellet stove means a cleaner flue pipe and cleaner air around your and your neighbors’ homes. You can now easily search for the cleanest pellet stoves on the EPA's new searchable database.

6.       6. Beware of efficiency numbers on manufacturer and retailers websites.  As with BTUs, manufacturers routinely exaggerate the efficiency of their stoves on their websites, so if efficiency and saving money is important to you, check the EPA list of stoves for efficiency ratings.  Until May 2020, many companies still hadn't even reported their efficiency to the EPA, but thanks to new regulations, all companies have to test for and disclose their efficiency.  Pellet stoves range from 58 to 87% efficiency, so do your homework and check the EPA list.  As of Jan. 1, 2021, consumers can get a 26% tax credit when buying and installing pellet stoves that are 75% efficient or higher. Click here for more details.

Do not rely on Manufacturers Certificates that claim their stoves are eligible for a federal tax credit without first checking the efficiency on the EPA's searchable database of certified heaters.  Even large companies that make good quality stoves like Jotul and QuadraFire have claimed that stoves as low as 66% efficiency are eligible for the tax credit.  The credit is supposed to be for stoves over 75% efficiency.  

The EPA used to allow companies to calculate efficiency based on a default of 78% efficiency, even though most pellet stoves are below that, explains Ben Myren, who runs one of the stove test labs approved by the EPA. The result is a 5-10% exaggeration of some stoves on the EPA site, something that the EPA has not publicly acknowledged. (Some incentive and change out programs - Maryland, Massachusetts and New York - require that the stove have an efficiency listed on the EPA list to get the full rebate.)

Appreciating these six factors are likely to help you make a better decision, but we also encourage consumers to rely on feedback from friends, neighbors and others who own pellet stoves. One site that can be helpful for research is hearth.com.  

A final note of caution is to take advertised hopper size with a grain of salt.  Most manufacturers also exaggerate hopper size.  Of the six models we tested, Harman and Ravelli exaggerated their hopper size by 15 – 18%, while Enviro didn’t exaggerate at all.  Choosing a stove with an advertised hopper size of 50 – 60 pounds can be a good idea, as it means the hopper will likely hold 45 – 55 pounds and you can empty an entire 40 pound bag in it when its low.