Trump Administration to change Obama era wood stove and boiler emission regulations

Delaying or weakening emission regulations will impact thousands of communities nationwide
The EPA is “taking steps to provide relief to wood heater manufacturers and retailers” according to a statement released by the EPA.  The EPA expects to issue a proposed rule this spring that could potentially weaken parts of the regulations enacted under the Obama administration.
This move is supported  by companies such as Central Boiler, the largest outdoor wood boiler manufacturer in North America, who has been aggressively lobbying to delay and weaken the standards that were to come into effect in 2020. But to some smaller companies who have already invested in the R&D to meet the stricter 2020 standards, the EPA announcement undermines the significant investment they’ve made in designing cleaner and more efficient wood heaters. 
Thousands of cities, towns and communities are impacted by excessive wintertime levels of wood smoke, posing health risks and undermining support for an iconic renewable energy technology.
It is widely expected that part of the relief that EPA will be providing to industry is a three-year delay in the emission standards that were  set to take effect in June 2020.  Republicans in the House of Representatives had already passed legislation for a three-year delay, but the Senate has not.  A court filingby the EPA said that it “intends to take final action on this first proposed rule by this fall,” and that would allow manufacturers to slow down their R&D and certification testing.
But the EPA can pick and choose which parts of the Obama era wood heater regulations that it wants to rewrite and they say they will issue a series of federal register notices asking stakeholders for comment and input on substantive issues.  Experts believe that a statement released by the EPA indicate that emission test methods are being considered. 
Environmental groups, industry and the EPA have been wanting to move away from testing and certifying wood stoves with crib wood – 2x4s and 4x4s – which has been the standard testing fuel since the first set of wood stove regulations in 1988.  All parties want to switch to using cordwood, the fuel used by homeowners, recognizing that stoves have been fine tuned to run better on crib wood, rather than cordwood.  This has resulted in stoves that may run at 4 grams an hour of smoke in the lab, but may be 10 grams an hour or more in the hands of homeowners. In a statement this week, the EPA said it is concerned that its regulation“may not be achieving the environmental benefits it was supposed to provide.”  
The EPA appears likely to accelerate the transition to testing with cordwood but industry seems to favor an ASTM cordwood test method while some states and others are developing a new method that reflects how stoves are used by homeowners.  This method, call the Integrated Duty Cycle (IDC) method is still in draft form and is a drastic departure from the traditional way that stoves have been tested since the 1988.  
The EPA could also decide to weaken emission limits for wood boilers, which would primarily benefit the outdoor wood boiler industry led by Central Boiler.  
Since the 2015 regulations went into effect, scores of wood and pellet stoves and boilers have been tested to meet the 2020 standards and most prices have not gone up significantly.  The 2015 regulations began a process of requiring that manufacturers test and report their efficiencies, and delaying the 2020 deadline would set back efficiency disclosures, harming the ability of consumers to choose more efficient appliances. 
States are allowed to set stricter standards but not looser ones, and if the EPA were to weaken the federal rule too much, some states could either stick to the original standards set by the Obama administration in 2015 or develop new ones. States like New York, Oregon, Vermont and Washington are already battling long-term wood smoke problems and have started to chart their own course for wood heater regulations. If several states adopted a different cordwood test method or stricter emission standards, they could have a “California effect” of moving the entire market.
“We are very concerned that the Trump Administration  may weaken consumer and environmental protections for wood stoves,” said John Ackerly, President of the Alliance for Green Heat, an independent non-profit that promotes cleaner and more efficient residential wood heating. “Wood and pellet stoves are vital to help families affordably reduce fossil heating fuels, but we can’t move this technology forward unless they can burn cleaner in people’s homes,” he said. 

Heated Up!

Tiny homes, tiny wood stoves: photos, ideas and designs

With the advent of the tiny home movement, there is a rise in interest in tiny stoves to heat them.  Tiny stoves have always been around, mainly driven by the sailboat industry, but also for yurts and small homes.  Small stoves are often thought of as stoves with a firebox of less than one cubic foot.  But some are much smaller than that and may put out no more than 10,000 BTUs.  There will also likely be a growing market for very small pellet stoves, like the Thelin Gnome, as living spaces get smaller and tighter. 
The paradox of heating a small space is that it may not be hard to heat up, but it also gets cold quickly after the stove goes out.  The fireboxes are so small that they go out quickly.  Often, tiny stove need to be reloaded every 20 – 60 minutes, depending on the size of the fuel and whether the stove is just getting going or has a decent coal bed.
A few of these stoves are EPA certified, including the Kimberly and the Gnome pellet stove.  If they are designed for boats, vans, trailers or for camping or other non-residential spaces, they should fall outside the EPA’s regulations, which only pertain to residential heating.  However, even if they do not require to pass EPA emissions testing to go on sale, they may not be allowed to be installed in a tiny home.  See our other photo essays on wood stoves styles around the world, wood fired hot tubs and firewood gathering around the world.

To minimize space, tiny stoves can be mounted on the wall. Using wood stoves in boats, vans and tiny homes can pose a great risk of carbon monoxide build up than in larger spaces. Be sure to install a CO detector, store your ashes outside and ensure the draft doesn’t reverse back down the chimney.
Tiny stoves are often installed on counters or shelves so that operating and cooking on them is easier.

Yurts are traditionally heated with larger, inefficient stoves, not small, sleek ones like this.  

Inside a traditional style “Sheep Wagon” in Idaho

This Van found on Vancouver Island, BC spotlights a small stove and split wood


The Gnome pellet stove is the smallest pellet stove on the market and claims to run for more than 24 hours on one hopper load of pellets at low heat.

The Viking 30 cookstove is part of a retro line of wood stoves from the UK.

A small stove in a classic Airstream trailer.

Heated Up!

$300 wood heater tax credit extended retroactively for 2017

This map shows which states historically
have the highest percent of residents
claiming the energy tax credits, including
the credit for wood and pellet stoves.

Feb. 9, 2018 – Today President Trump signed into law a budget deal that included a one year, retroactive extension of the wood heater tax credit.  Thus, consumers who bought stoves that are 75% efficient or higher may qualify for a $ 300 tax credit on their 2017 taxes.

However, stove manufacturers often mislead consumers into thinking they are buying a stove that is at least 75% efficient when in fact it may be in the low or mid 60s. Manufacturers are allowed to self-certify which stoves are eligible for the credit and some appear to ignore any common sense definition of the Congressional language which stipulated requiring a stove “which has a thermal efficiency rating of at least 75 percent.”

The Alliance for Green Heat is calling on HPBA and stove manufacturers to publicly support and abide by a policy of only recognizing the average, overall efficiency of stoves based on third party testing at an EPA approved lab.  Currently, some manufacturers will self-certify a stove to be eligible for the tax credit if it reached 75% efficiency on only one of its 4 burn rates. Others self-certify that their stoves are eligible when the stove did not reach 75% efficiency on any burn rate.

The Alliance for Green Heat supports tax credits and other incentives that focus on the cleanest and most efficient stoves.  However, he federal tax credit has no criteria for grams per hour and virtually all stoves have claimed to be at least 75% efficient, minimizing the underlying intent of a tax credit.

The definition of 75% efficient is still unresolved. The IRS recognized the use of the European lower heating value (LHV) efficiency measurement until 2010 when Congress removed the LHV language.  The efficiency measurement should have reverted to the North American standard of using HHV, but industry has continued to use LHV.  (A stove measuring 75% efficiency using LHV would be about 70% efficiency using HHV.)

We will update this blog as it becomes more clear which companies are self-certifying stoves at 75% efficient when they may only be in the low or mid 60s.

To be sure that you are buying a higher efficiency stove, check the EPA’s list of certified wood stoves, and choose one that with an actual, verified efficiency.  There are many non-cat stoves over 70% efficiency and many catalytic and pellet stoves over 75% efficiency.  Unfortunately, if you are buying a stove in 2018, there is no guarantee that you will be able to get a tax credit for it.  Congress may make the credit retroactive again in 2019, but then again, they may not.

For more background on the wood heater tax credit, click here.

Heated Up!

Top 10 stories in 2017 for wood and pellet heating

2017 may not have been the most momentous year for wood and pellet stoves, but every year is full of important stories and these are what we see as the top 10. Think we missed one of 2017’s top stories?  Leave a comment.
      1. Wood stove sales lag
Warmer winters and lower fossil fuel prices are likely the main causes of continued sluggish sales of wood stoves and inserts in 2017.  Gas appliances continue to gain in popularity.  The 2015 EPA regulations are rarely cited as contributing to the current malaise in the market, and local restrictions are unlikely to have much of an impact either.  The final weeks of 2017 and first week of 2018 brought arctic temperatures to much of the US, boosting sales of both pellets and stoves.  But will it last?
2. Funding for change out programs rolled back
Whoever thought a motorcycle company would deal a big blow to the stove industry?  To be fair, it had little to do with motorcycles and a lot to do with the Trump Administration wanting to do away with out-of-court air quality violations settlements that allowed polluters to pay part of their fine in programs that improve air quality.  Harley Davidson happened to be the poster child of companies willing to support a change out program, but not allowed to do so by the Trump Administration.  That pipeline of funding, up to 10 million a year, is now cut off, dealing another blow to programs seeking to get people to part ways with their old wood stove, and exchange it for a new pellet, gas or wood stove.
3. Congress – lots of expectation but no action
Three key initiatives – the BTU Act, the NSPS delay and the biomass heater tax credit – did not come to fruition in 2017.  All three initiatives remain in play in 2018, but with each passing month, 2018 will get more consumed by the fall election season. The BTU Act would help the entire biomass thermal energy sector and has some key backers, such as Senator Susan Collins (R-ME). The bills to delay NSPS deadlines by 3 years passed committees, largely on party lines.  With the razor thin majority in the Senate, Democratic support for these initiatives may be more important in 2018.
4. Cordwood test methods are on the rise
The ASTM E3053 cord wood test protocol developed largely by industry members was completed and is now an accepted alternative test method.  However, companies don’t appear to be lining up to use it to certify their stoves.  Meanwhile, NESCAUM is taking the lead in designing what they say is a much more realistic cordwood test method as it takes into account more frequent reloading.  That method appears to have EPA’s interest and may be more likely to be referenced by the federal and/or state governments.
5. The renewable energy movement gains steam, helping pellet systems
Despite a President who champions coal and fossil fuels, the renewable energy movement is gaining ground worldwide.  Automated pellet and chip heating systems are being installed more rapidly in Europe and are gaining wider acceptance in the US.  Pellet stoves and boilers are also becoming more recognized in green building circles.  Campuses, towns, cities and states striving to reduce fossil fuel use usually start with electricity and transition to green heating options. 
6. Anti-wood smoke groups gain legitimacy
In 2017, we saw a rise of clean air groups campaigning for more restrictions on wood stove installation and use.  Some of the core activists emerged years ago when their communities or homes were subjected to excessive smoke from outdoor wood boilers.  In 2017, the focus shifted more to wood stoves, mostly in communities in the West, but to some extent in the Northeast.  Often, tensions rose over lack of enforcement by local jurisdictions who didn’t have the resources, training and/or political will to deal with those creating excessive smoke.  Overall there is a growing recognition that wood smoke is a serious health concern and debates in local and state forums will likely grow in coming years.
7.  Consolidation of stove and pellet plants continues
In the wood and pellet stove world, Hearth & Home Technologies (HHT) did not announce major new acquisitions in 2017, but the company consolidated by moving Quadra-Fire and Vermont Castings production to its Pennsylvania facility.  However, 2017 also saw market share continue to slip away from higher-priced manufacturers like most HHT brands to the lower priced manufacturers that sell from hardware chains.  On the wood pellet front, Lignetics continued its buying spree, finalizing a deal to acquire New England Wood Pellet at the very end of 2017. 
8. DOE co-sponsors Wood Stove Design Challenge
After many years of sitting on the sidelines of thermal biomass, the Department of Energy found an entre in the 2018 Wood Stove Design Challenge.  DOE is providing funding and its PR department is issuing news releases, lending greater credibility and a higher profile to the event.  The competition features automated stoves and stoves that produce electricity to supplement wintertime solar PV output, showcasing new roles that wood stoves could play if they run more reliably cleaner in real world settings.  The competition will also showcase cordwood testing protocols and fossil fuel reductions achievable by wood stoves compared to solar panels.
9. NY, MD and MA recognize efficiency in stove programs
In 2017, three states began using efficiency criteria to determine eligibility in incentive or change out programs.  NY now requires pellet stoves to have verified efficiencies on the EPA list of certified stoves.  MD & MA provide higher incentives for stoves with verified efficiencies, as Oregon does, but with a far simpler formulas.  The rampant practice by most manufacturers of providing misleading and exaggerated efficiency values – a practice not tolerated in other HVAC sectors – motivated these states to act.
10. The new EPA wood heater regulations move forward
OK, 2017 was not a big news year for the new heater regulations, known as the NSPS.  But in 2017 all large forced air wood furnaces were required to be certified (including smaller ones who pretended to be large to evade certification in 2016).  In April, there were only six EPA certified furnaces ranging from 48% to 89% efficiency, now there are 16.  2017 was a pivotal year in that it marked the midpoint between 2015 and 2020, when all heaters must meet stricter emission standards.  And, with each passing month, more heaters become 2020 compliant as manufacturers hedge their bets in case Congress, the Administration or the courts do not derail the 2020 deadline. In 2017, some exciting new innovation hit the market, including automated MF Fire Catalyst, the Optima designed just to burn pressed logs and more coming soon.

Did we miss something?  Post a comment!

Heated Up!

Lessons in building a 120-Watt thermoelectric wood stove

Guest Blog: We are reposting a 2012 blog from Instructables by Tecwyn Twmffatt at Goat Industries. It describes an early effort to build a thermoelectric wood stove.  This blog is part of a series of blogs providing information for the 2018 Wood Stove Design Challenge.

Introduction: Thermoelectric Power Generation (TEG) 

These videos document my first attempts at generating electricity from a thermoelectric peltier device in 2012. The TEG that I used is a high powered unit able to withstand high temperatures and specially made for electricity generation. In terms of instructions, I don't think many people would want to build the 10 TEG system as it was ridiculously expensive, so I'm putting in a section for creating the 1 TEG arrangement, which is relatively easy and low cost.

Step 1: Part 2 of 3 

 


A ten unit Thermoelectric generator system is shown being constructed and then fitted to a wood burner. The theoretical maximum output is 200 watts. The video shows how the generator was put together and how the wood burner was modified to get maximum heat through the TEGs. The TEGs themselves are able to withstand a constant 325 degrees C on the hot side and require plenty of heat to get the 20 watts that each of them are capable of producing.

Step 2: Part 3 of 3 

 


In part 3 we successfully generate a significant amount of energy from the woodburning stove. In the first session, a circulation pump, a fan and 10 x 10 watt flood lights are powered up. In the second session, we attempt to get a more balanced load wired up to the tegs and measure a noticable increase in power output. The 10 tegs are wired up in 2 parallel strings and, from the manufacturer's specification, the optimum output voltage is 14.4v . The nearest that we manage is 13.8v, at which we generate 120 watts. The specifications suggest that 200 watts is possible when the load is matched.

Step 3: Full Playlist


31 Minutes of Thermoelectric video heaven!

Step 4: Creating the 1 TEG Generator


Here we are going to build the single TEG generator shown in the first video.

Step 5: Tools and Equipment  


Parts: 
Thermoelectric power generator TEG module (GM250 449 )
...... buy direct from China at: www.thermonamic.com/
Aluminium block 102 x 115 x 20 mm
Steel block 102 x 115 x 10 mm
1/4" BSP blanks x 6 of
1/4" BSP male stud push fit pneumatic fittings for 10 mm pipe x 2 of (See photo above)
5 mm Hex bolts x 40 mm x 2 of
25 litre water butt
OD 10 mm ID 8 mm nylon pneumatic pipe
12V water pump
12V LEDs, 1 watt x 20 of Tools:  1/4" threading tap
5 mm metric coarse threading tap
Drill 11.5 mm
Drill 5.5 mm
Drill 4.2 mm
Drill press
Torque wrench
MIG welder
Plasma cutter / Grinder with cutting discs
GM250-449-10-12.pdf

Step 6: Drilling and Tapping the Cooling Block


Use the engineering drawing to produce internal coolant passage ways in the aluminium block. I ended up drilling all the way through to the other side and using more of the 1/4" blanks. Connect the 1/4" pipe fittings to the block and plumb in the pump. Add antifreeze to the water in the water butt if it's likely to get cold at all. To create a 'sandwich' with the hot block (steel block), the TEG and the cooling block, drill and tap holes in the steel block for the 5mm bolts. Weld the hot block into the side of the wood burner and recreate the TEG sandwich, tightening the bolts up with a torque wrench (see attached file). Connect up LEDs on the TEG, turn on the pump, light the wood burner and off you go!
TEGinstallationandspecifications01.pdf

Step 7: 10 TEG Layout



If you really must build the 10 TEG generator, the photo above shows what is involved. I have got CAD drawings, PCB drawings etc. If anybody is interested. Not for the faint hearted! PCB 03.pcb
PCB 01.zip
CAD files 02.zip Heated Up!

Opinions of top wood stove industry insiders revealed in 1998 interviews

The late Paul Tiegs, one of the
greatest authorities on wood
stoves, conducted the
interviews for the EPA. 
Long before the regulatory debate about wood stoves heated up in the 2010s, the EPA commissioned a series of fascinating interviews with the top wood stove experts in the country on a host of technical and policy issues.  These interviews give a glimpse of the opinions and philosophies of industry and academic leaders at a time when they apparently felt free to go on the record about what became controversial topics. 
The content of these interviews remains very relevant today for anyone interested in a behind-the-scenes look at many of the underlying issues in the 2015 EPA stove and boiler regulations.  The interviewers – Jim Houck and Paul Teigs (who are top experts themselves) – asked questions ranging from whether masonry, pellet, boiler and furnace appliances should be regulated, to the vulnerabilities of catalytic stoves, to how lab testing can better reflect real world use of stoves. 
These interviews remain a valuable resource because each of the nine experts was asked the exact same questions.  Thus, if you are interested in masonry heaters, or catalytic or pellet stoves, or how labs coax the best numbers from stoves, it is relatively easy to scroll down and see how each person answered the question.  Of the nine interviewees, four are from industry (John Crouch, Bob Ferguson, Dan Henry and Michael Van Buren), two from test labs (Rick Curkeet and Ben Myren), two from academia (Skip Hayden and Dennis Jaasma) and one from EPA (Robert C. McCrillis). Their full titles and affiliations are at the end of this blog along with the full list of questions asked.  The full set of questions and answers are in Appendix B on page 58 and can be downloaded here (pdf).
In general, Bob Ferguson and Dan Henry tended to oppose further regulation, and felt, for example, that pellet stoves and wood-fired central heating appliances did not need to be regulated.  Ben Myren tended to favor a blanket approach of closing loopholes and regulating all appliances.  This difference in views between two industry experts and one test lab expert can be viewed through their respective economic interests and how it would affect their livelihoods.  But these interviews also show deeper philosophical differences and illuminate the reasons for their positions, whether they concern the health impacts of wood smoke, profitability, practicality of test method changes, etc.
We have chosen to reproduce the answers to two questions and invite readers to refer to the full set of interviews to find issues that they may be more interested in, such as the impact of wood species on emissions, stress testing to see how durable stoves are, and options to promote or require education or maintenance of stoves by consumers. 
When the Alliance for Green Heat began ten years after these interviews in 2009, much of the content had already been seemingly lost or obscured.  Very few people, for example, knew of the origin or impact of the 35:1 air-to-fuel ratio loophole that allowed pellet stove manufacturers to make low efficiency stoves in order to avoid regulation.  Right up until 2014, state and federal government agencies, along with top industry outlets, continued to propagate myths about pellet stoves.  Even the EPA never advised consumers that uncertified pellet stoves were likely to have lower efficiencies due to the 35:1 loophole they created.  These interviews provide the best information anywhere on how this came to be and what impact it had on the pellet stove industry and consumers.
We chose the question about whether central heaters should be regulated because this turned into one of the biggest issues in the 2015 regulations.  Only one interviewee – John Crouch – saw a causal relationship between the rise of outdoor wood boilers and the 1988 emissions regulations. 

Question: The 35:1 air-to-fuel ratio cut-off for certification has produced two classes of pellet stoves — those that are certified and those that are not. The latter class may have models that are less efficient and have higher emissions than the former. Should the regulations be amended to close the loop-hole and discourage the practice of intentionally designing models with a higher air-to-fuel ratio to avoid certification?


John Crouch, HPBA’s
foremost wood stove expert.

John Crouch, HPBA: I wouldn’t use the term “close the loop-hole”. I would say, “is the proper place to cut off the definition of a wood heater?” We all know the whole discussion during the Reg-Neg ignored this emerging category of pellet stoves. So this gets back into my other broader comment, which is, instead of going back in and changing the NSPS in a piecemeal fashion, there needs to be a true revision of the whole thing that deals with the category of pellets and masonry heaters and outdoor furnaces.

Rick Curkeet, Intertek: Yes. The way to amend the regulation is to simply remove the 35:1 air/fuel ratio exemption. This has never been required by fireplaces (they meet the 5 kg/hr minimum burn rate exemption criterion anyway). Pellet units are readily able to meet emissions requirements and the exemption only encourages making these units less efficient to avoid the regulation.

Bob Ferguson, Consultant: The 35:1 cutoff was intended for fireplaces. However, pellet stoves are the only product that even take advantage of the air-fuel exemptions. Fireplaces generally use the burn rate exemption. Pellet stoves probably don’t need to be regulated at all. They are all quite clean burning. Let the marketplace decide if exempt stoves are acceptable. If pellet stove users demand products that use fewer pellets (more efficient), the manufacturers will respond. 

Skip Hayden, Researcher: Yes. In Canada, we recommend that people buy only EPA-approved pellet stoves. We have developed a high ash pellet stove that’s operating around 85% and its emissions are about 0.3 g/hr or less. 


Dan Henry, a founder of Quadrafire
stoves is one of industry’s most
articulate spokesmen.

Dan Henry, Aladdin: There is no data that indicates that even a poorly operating stove is a dirty burning appliance. They are inherently clean, becoming more and more reliable, and don’t fix them if they aren’t broken.

Dennis Jaasma, University of VA: Pellet stoves are inherently clean burning unless there is something very bad about their design. I am not concerned about regulating the currently uncertified units unless their field emissions are bad compared to certified stoves.

Robert C. McCrillis, EPA: Yes, all pellet stoves should be affected facilities and not subjected to that 35:1.

Ben Myren one of Amreica’s most
thoughtful and experienced stove tester.


Ben Myren, Myren Labs:  I agree, no more loop-holes. The new technology stoves that are coming on the market are going to be totally new critters. I don’t think that turning down the air- to-fuel ratio, to make it whatever it is, should get you out of the loop. Some of those suckers have got to be just filthy. I mean you look at the flame. I’ve seen them burn at the trade show; you know, the glass is sooting up on the edges. You can just see it.

Michael van Buren was a technical
expert with The Hearth Products
Association, now HPBA

Michael Van Buren, HPBA: I don’t know what that loop-hole does, whether it really affects the operation of the stove and the efficiency of the stove.

Question: According to a Department of Energy survey out of the 20.4 million households that used a wood burning appliance in 1993, less than 0.3 million used a wood burning furnace as their primary source of heat. Are there enough wood-fired central heating furnaces in use to merit their closer evaluation? How many commercially available models are there? Are there emissions data for them? Should they be certified?

John Crouch: The [1988] EPA New Source Performance Standards killed the indoor furnace industry and created this little loop-hole which the outdoor furnace industry is beginning to exploit and kind of underscores the need for a more comprehensive wood burning regulation which sets out over a several year period to codify all forms of wood burning technology.

Rick Curkeet tested stoves for Intertek
labs and is one of industry’s top experts.


Rick Curkeet: I don’t know how many new units are being produced but I’m sure it’s a very small number. Still, one really poor unit can be a significant problem if it’s in your neighborhood. There have never been any standards for testing this type of product for emissions and efficiency. However, we have adapted existing methods and can say that the performance range is very wide. Poor designs may be 30% or less efficient and produce nearly 100 grams/hr emissions rates. Good designs are able to approach certified wood stove performance levels.

Bob Ferguson: I don’t feel there are enough units being sold to merit any activity what-so-ever. There are only a handful of manufacturers. I don’t think there has been anything published–so if testing has been conducted, it is probably a good assumption that the numbers aren’t that good. They shouldn’t be certified, as you would have to develop test methods and standards. The country would be better off using the money to pay manufacturers to phase out of production, sort of like the agricultural method of paying farmers not to grow certain crops.

The late Skip Hayden, one of the main
wood stove authorities during the 1980s
and 1990s.


Skip Hayden: The number of central wood furnaces in Canada, certainly in comparison to the United States, would be higher. In our Eastern provinces, it’s a relatively common add-on to existing oil furnaces. Generally, they are as dirty as can be.

Dan Henry: I think a lot of these are used in rural areas and considering the fuels that are out there, I don’t think they should be regulated. Maybe just a spot check of some sort. I think the only thing that would benefit would be the testing laboratories. If it emits particulate into an air shed where it can have an adverse effect on the industry (my ability to make a living), then yes.

Dennis Jaasma
also ran a research
test lab at the
 University of VA.


Dennis Jaasma: Yes, central heaters merit further evaluation. I don’t know how many models are available. I think EPA has done some work on them, but I do not know any results. Yes, they should be certified. They are in danger of becoming extinct if they don’t wind up with a certification program.

Robert C. McCrillis: In some localities I think these furnaces are a problem; I don’t know how many are commercially available. I think I can name off six or eight companies and each one makes several models, but I don’t know what the total market is, maybe 10,000 – 15,000 a year. The little bit of testing that we did here, says that they are probably on a par with a conventional wood stove. The way those things work, they have a thermostatically operated draft and when the thermostat shuts off the draft closes, so you get this real smoldering burning situation. Secondary combustion technology probably wouldn’t work. Possibly a catalytic technology would, but I just don’t think it stays hot enough in there. I guess that really depends on the impact.

Ben Myren: I don’t think they should be exempt for any reason. As to the rest of it–are there emissions data for them? I suspect there are. Should they be certified? Yes they should be certified. Nobody should be exempt from the process.

Michael van Buren: I think there should be some type of testing on them.


List of Experts Interviewed
Mr. John Crouch, Director of Local Government Relations, Hearth Products Association (CA) [now HPBA]
Mr. Rick Curkeet, P.E., Manager, Intertek Testing Services (IL)
Mr. Bob Ferguson, President, Ferguson, Andors and Company (VT)
Dr. Skip Hayden, Director, Combustion and Carbonization Research Laboratory (Ontario, Canada)
Mr. Daniel Henry, Vice President, Aladdin Steel Products, Inc. (WA) [now Quadrafire]
Dr. Dennis Jaasma, Associate Professor, Department of Mechanical Engineering, Virginia Polytechnic Institute and State University (VA)
Mr. Robert C. McCrillis, P.E., Mechanical Engineer, Air Pollution Prevention and Control, Division, U.S. EPA (VA)
Mr. Ben Myren, President, Myren Consulting (WA)
Mr. Michael Van Buren, Technical Director, Hearth Products Association (VA) [now HPBA]
Interview Questions
RWC Technology Review
Environmental Protection Agency Order no. 7C-R285-NASX
prepared by
OMNI Environmental Services, Inc.
Beaverton Oregon 97005
1. State-of-the-art of wood stove combustion and emission control technologies.
  1. 1.1  Are in-home emission reductions as compared to conventional stoves shown in Table 1 for catalytic and non-catalytic certified stoves reasonable?
  2. 1.2  Are efficiencies shown in Table 2 for catalytic and non-catalytic certified stoves reasonable?
  3. 1.3  Can catalytic technology for use in wood stoves be fundamentally improved?
  4. 1.4  Is the use of manufactured fuel (densified and wax logs) a credible emission
reduction strategy? See Tables 1 & 2 .
  1. 1.5  For non-catalytic stoves the heat retention adjustment with refractory material of various densities can reduce particulate emissions. How big an effect can this have?
  2. 1.6  Approximately one half of the particulate emissions occur during the kindling phase for non-catalytic wood stoves and more than half for catalytic wood stoves. Are there improvements in technology that can mitigate this problem? Can specially designed high BTU wax logs be used to achieve a fast start and reduce kindling phase emissions?
  3. 1.7  Should masonry heaters with tight fitting doors and draft control be classified as a wood stove and be subject to some type of certification even though most weigh more than 800 kg?
  4. 1.8  Are the emissions and efficiencies for masonry heaters, based on in-home tests, shown in Tables 1 and 2 reasonable?
  1. 1.9  The OMNI staff feels the emissions per unit of heat delivered (e.g., lb/MBTU or g/MJ) is a more appropriate way to rank the performance of wood burning appliances than emission factors (lb/ton or g/kg) or emission rates (g/hr). — Comments?
  2. 1.10  Default efficiency values are used for wood stoves. This coupled with the fact that emission factors or rates (not g/MJ) are used to rank wood stoves does not provide an incentive for manufacturers to increase the efficiency of their stoves. — Comments? Should an efficiency test method as described (FR v. 55, n 161, p. 33925, Aug. 20,1990) be required to be used and the results listed?
  3. 1.11  Have certified stove design and performance improved since the first certified stoves? If so, how?
  1. State-of-the-art of fireplace emission control technology.
    1. 2.1  Are the emission factors and efficiencies for the in-home use of fireplaces and inserts shown in Tables 3 and 4 reasonable?
    2. 2.2  There appear to be only a few practical design or technology options for fireplaces that will potentially mitigate particulate emissions. — What designs and technologies are available? What retrofit options are there?
    3. 2.3  The use of wax fire logs reduces emissions over the use of cordwood. Can the formulation of wax logs be changed to produce even less emissions?
    4. 2.4  What are the distinctions between a masonry fireplace and a masonry heater?
    5. 2.5  As with wood stoves, the OMNI staff believe that the mass of emissions per unit of heat delivered is a better way to rank the performance of fireplaces than emission factors or emission rates.
  2. State-of-the-art of wood-fired central heating furnace emission control technology.
3.1 According to a Department of Energy survey out of the 20.4 million households that used a wood burning appliance in 1993, less than 0.3 million used a wood burning furnace as their primary source of heat. Are there enough wood-fired central heating furnaces in use to merit their closer evaluation? How many commercially available models are there? Are there emissions data for them? Should they be certified?

4. State-of-the-art of pellet-fired wood stove technology.
  1. 4.1  Are the emissions and efficiencies for the in-home use of pellet stoves shown in Tables 1 and 2 reasonable?
  2. 4.2  The 35:1 air-to-fuel ratio cut-off for certification has produced two classes of pellet stoves — those that are certified and those that are not. The latter class may have models that are less efficient and have higher emissions than the former. Should the regulations be amended to close the loop-hole and discourage the practice of intentionally designing models with a higher air-to-fuel ratio to avoid certification?
  3. 4.3  Have pellet stove design and performance improved since the first models were introduced? If so, how?
1. Ramifications of ISO.
5.1 The International Organization for Standardization (ISO) has a technical committee for developing emissions, efficiency and safety test standards for wood-fired residential heaters and fireplaces. (See Table 5 for comparison of the draft ISO method 13336 with EPA methods 28, 5G and 5H.) Do you feel that the EPA methods should be replaced with or be made comparable to an international standard?
  1. Correspondence between in-home and laboratory emission test results.
    1. 6.1  How accurately do certification tests predict in-home performance?
    2. 6.2  How would you design research testing in the laboratory to simulate in-home use?
  2. EPA Method 28 strengths and weaknesses.
    1. 7.1  Method 28 is in part an “art”. Fuel loading density, fuel moisture, fuel characteristics (old vs new growth, grain spacing, wood density) and coal bed conditioning can be adjusted within the specification range of the method to influence results. In your experience what things have the most effect on particulate emissions? How much influence can they have?
    2. 7.2  Burn rate weighting is based on very limited data and the cities from where the data were obtained are not very representative of wood use nationwide (see Table 6). How can the weighting scheme be improved to be more representative of the nation as a whole?
    3. 7.3  The equation for the calculation of the air-to-fuel ratio as in Method 28A is in error. The error produces a small but significant difference in the calculated air-to-fuel ratio. Should the method be corrected or should it be left as a “predictor” of the air-to-fuel ratio?
7.4 The assumed mole fraction of hydrocarbons (YHC) is defined as a constant in the air-to-fuel ratio calculations in Method 28A. The mole fraction of hydrocarbons in the vapor phase will vary significantly with fuel and combustion conditions. Should hydrocarbon vapors (more appropriately, organic compound vapors) be measured as part of the method?
4. EPA Methods 5G and 5H correlations.

8.1 The comparison data to demonstrate the correlation between 5G and 5H are limited. Should the correlation between the two methods be reevaluated?
  1. Performance deterioration of EPA-certified wood stoves in the field.
    1. 9.1  It is the opinion of many in the wood stove industry that catalysts last only five years and that a stove designed for a catalyst operated without a functioning catalyst can produce as much emissions as a conventional stove. — Comments?
    2. 9.2  Field studies in Glens Falls, NY, Medford, OR, Klamath Falls, OR and Crested Butte, CO showed that emissions from some catalytic stoves became appreciably worse even after two to three years of use. Inspection of stoves in Glens Falls showed that catalyst deterioration and leaky bypass systems were responsible. Have improvements been made in the design of catalytic stoves to minimize these problems? Is it reasonable to require homeowner training on the proper use of catalytic stoves and/or to incorporate into their costs an inspection and catalyst replacement program?
  2. Stress test pros and cons.
    1. 10.1  A short-term laboratory woodstove durability testing protocol was developed to predict the long-term durability of stoves under conditions characteristic of in- home use (see EPA-600/R-94-193). It was concluded in that study that damage occurs during those occasional times when a woodstove is operated in the home at exceptionally high temperatures. The laboratory stress test was designed to operate a woodstove at very high temperatures over a one to two week period to predict long-term durability under in-home use. Is this a reasonable approach?
    2. 10.2  Should a stress test be made part of the certification process?
  3. Feasibility of developing separate emission factors for dry and wet wood and for
softwood and hardwood species classes.
  1. 11.1  Optimum wood moisture for low particulate emissions seems to be in the 18% to 20% range. Are you aware of any data that will allow the impact of wood moisture to be isolated from other variables? Could it be different for wood from different tree species?
  2. 11.2  Wood from different tree species clearly burns differently. The chemical make-up and density of wood from different tree species is different. For example wood from coniferous trees has more resin than wood from deciduous trees. It is believed that particulate emission factors will be different for wood from different tree species. If this is true different parts of the country may have different emissions factors for residential wood combustion. Are you aware of any data that document different emission factors for wood from different tree species?
8. Routine maintenance.
12.1 Would routine maintenance of stoves once they were in a home reduce particulate emissions? Would this be more relevant for catalytic stoves than non-catalytic stoves? Would this be relevant for pellet stoves with electronic and moving parts?
  1. 12.2  Should the home owner be provided with a maintenance manual or a training course at the time of purchase? Should a maintenance program be part of the purchase price particularly for catalytic stoves?
  2. 12.3  What would the key elements of routine maintenance be?

– end –

Heated Up!

Could a Thermoelectric Wood Stove Pay for Itself?

By Ken Adler, AGH Senior Technical Advisor

Payback calculations are common in the residential solar photovoltaic industry where homeowners want to know how long it will take for them to recoup their initial investment. If you purchase panels outright, payback periods depend on a variety of factors including a utility’s price for electricity, tax incentives, and amount of daily sunlight hours. A range of 5 to 8 years is possible however, it can be as wide as 3 to 15 years.[1]

Answering the payback question for thermoelectric wood stoves is one of the objectives for the 2018 Wood Stove Design Challenge. In the meantime, there are several ways to begin answering this question with information already available. It is also useful to look at how use of a thermoelectric wood stove in combination with another energy-saving system, i.e., solar, could prove beneficial to the homeowner and thus both industries as well. For example, in northern states and Canada, a thermoelectric wood stove could reduce the number of residential panels needed and thereby save the homeowner thousands of dollars in panel costs.

Early Thoughts on Payback

The retail price of a thermoelectric module is around $ 57.50 for a 22-watt module, or $ 2.61 per watt.[2] One critical point to make here is that the power output of our 22-watt module assumes an optimal hot-side temperature of 300 C (572 F) and cool-side temperature of 30 C (86 F). This ideal temperature differential is very difficult to achieve in real world conditions, so the real-world cost per watt for thermoelectric modules will be higher. However, cost should decrease and efficiency improve with widespread adoption of thermoelectric modules, similar to what happened in the solar industry. For example, DOE estimated that the installed cost of a solar panel declined from $ 7.06 per watt in 2009 to $ 2.93 in 2016, a reduction of 60 percent.[3] If we go back to 1977, the cost of a solar panel was $ 77 per watt. It is not unreasonable to expect a decline for the cost of thermoelectric modules as economies of scale reduce production costs.

Of course, when a thermoelectric module is placed into a wood stove there are other associated costs. The primary cost by far is the heat exchange system. As I’ve discussed in a previous post, to generate at least 100 watts of power, it’s likely that a water-cooled heat exchange will be needed. The current retail price for a 100-watt water cooled thermoelectric generator, which includes eight thermoelectric modules, is $ 599, or $ 5.99 per watt. One question the competition will attempt to answer is how much this heat exchange will cost when it is integrated into the design of the wood stove.

Secondary cost considerations include the price of the wood stove, its installation, and fuel costs. The price for a larger size 50,000 BTU wood stove can range from $ 900 to over $ 4000, and the average consumer spends about $ 2,500. Since a thermoelectric wood stove would be providing both heat and electricity, it is difficult to separate out how much of the cost of the stove is for each function. The more crucial point for now is that many larger size stoves, which can generate up to 50,000 BTUs and meet the 2020 EPA NSPS standard, are available for as little as $ 1,300. While this does not include the cost of installation, it does suggest that the wood stove portion of the costs should not be a major obstacle.

The cost of installing a thermoelectric wood stove into a home should not necessarily be that much greater than the cost of installing a traditional wood stove. One additional cost will be attaching the power outputs from the thermoelectric wood stove to an inverter. However, if we assume that early adopters will already have or are planning to get a solar PV system (more on this below) the cost of the inverter would not be a major obstacle.

Finally, one can assume that the fuel cost for a thermoelectric wood stove is essentially zero because the wood stove is already being used to heat the home. A thermoelectric module will convert only 3 to 6 percent of the heat from a woodstove into electricity, while the remaining 94 to 97 percent passes through the module and is released as heat into the home. In other words, the module is only using a very small percentage of the heat generated by the stove to produce electricity.

Value in Combining Technologies

While more in-depth analysis is needed, it’s possible that a thermoelectric wood stove could help reduce the size and cost of solar PV systems in northern climates that have limited sunlight/solar radiation in winter. For example, a typical 5000 watt solar PV system in Vermont produces 6,280 kWh of electricity per year, while the same system produces 7,913 kWh in Los Angeles.[4] Most of this difference is due to the low winter time output in Vermont between October and February: For example, the Vermont system produces 239 kWh in December, as compared to the Los Angeles system’s 473 kWh. If the Vermont resident wanted to generate the same amount of power as in Los Angeles, they would need to increase the size of their solar PV system from 5000 watts to approximately 6300 watts. At the current cost of approximately $ 3.36[5] per watt installed for residential solar, this could cost the Vermont resident an additional $ 4,368 for additional solar panels.

Alternatively, instead of purchasing extra solar panels, the Vermont resident could invest in a thermoelectric wood stove to boost their winter time power output. As we mentioned in our previous blog, a wood stove with a 150 to 200-watt thermoelectric generator operating 16 – 20 hours per day could generate 93 to 124kWh of electricity per month, which would be a good boost to the Vermont output of 239 kWh in December. And, at 0.16 $ /kWh for electricity in Vermont, the thermoelectric wood stove could save the homeowner an additional $ 15 to $ 20 per month.

While a real payback calculation for a thermoelectric wood stove will need to wait until prototypes go through more testing and we get results from the 2018 Wood Stove Design Challenge, the available information suggests thermoelectric wood stoves could help reduce the cost of residential solar installations, and potentially save homeowners thousands of dollars.

[1] http://solar-power-now.com/the-typical-solar-panel-payback-period/
[2] See our Resources page for a list of thermoelectric retailers.
[3] NREL. U.S. Solar Photovoltaic System Cost Benchmark. September 2016. In 1977, solar panels cost $ 77 per watt.
[4] NREL PVWatts Calculator
[5] EnergySage. Solar Marketplace Intel Report. April 2017.


Heated Up!

The Alliance for Green Heat pursues retailers advertising uncertified wood furnaces

Six of the nine retailers AGH contacted stopped advertising uncertified furnaces within two weeks

Indoor furnaces are usually in the
basement, but can be in a garage.  Either
option often leads to better fuel storage
practices than outdoor boilers and
greatly reduces jacket losses.

On May 15, 2017, EPA regulations took effect that required all wood furnaces to include smoke the law changed on May 15.
reduction technologies and be certified by third party test labs. Some furnace manufacturers started educating their retailers early and stopped shipping uncertified furnaces during the winter. Others continued to ship units, and many retailers continued to advertise and sell uncertified furnaces after

Indoor wood and coal furnaces—also called warm, hot air, or forced air furnaces—were very popular in the US through the early to mid-1900s, then gradually their lost market share as fossil liquid fuel furnaces gained traction in the late 1900s. Then, outdoor wood boilers gained favor, becoming a far worse threat to local air quality than indoor furnaces and boilers had been for decades.

The Alliance began contacting retailers advertising uncertified furnaces to find out whether they knew about the change in regulations and how responsive they would be to information about the change. “We believe that all manufacturers and retailers should play by the same rules, so that the ones who do follow the rules don’t get undercut by ones who do not,” said John Ackerly, President of the Alliance for Green Heat. “And, we found that many if not most retailers will stop advertising products that are not legal to sell if they are politely and professionally approached by an organization that is knowledgeable about the rules,” Ackerly said.

AGH Project Manager Melissa Bollman contacted nine retailers advertising uncertified furnaces. Of those, six stopped advertising those boilers within 2 weeks. Some of the furnaces were removed from the website entirely or are listed as unavailable, while other models that were previously advertised as capable of burning wood or coal have been rebranded as “coal only” to comply with EPA regulations.  Currently, if a stove or boiler is advertised as being able to burn wood, it must be tested and certified to burn wood.  (The EPA does not regulate coal heaters and some manufacturers have just added a grate and continue to sell the same unit as “coal only”.)

AGH efforts were not always effective, and a few retailers still appear to be advertising uncertified wood furnaces (see screenshots below). These include Sears’ online marketplace (orders fulfilled by the third party 123Stoves, Inc.), Homeclick, and HVAC direct. All screenshots were taken on June 22, 2017.

Houzz.com, Wayfair, and HVAC direct continue to sell uncertified wood furnaces or ones that are labeled wood/coal. The units they are selling are all made by US Stove Company, whose business model leaves it vulnerable to illegal sales of its units by multiple retailers.

AGH regularly monitors advertising by manufacturers and retailers in order to better educate consumers about misleading claims. We also publicize the names of manufacturers who provide better information and do not mislead consumers.

This continued advertising and sale of products that are no longer compliant highlights the danger that stranded inventory can pose for retailers when deadlines pass. If the 2020 emission rules are not delayed or changed, some wood stove retailers may get stuck with inventory that they are no longer allowed to sell, but are under pressure to unload to recoup their investment.

Without regulation, wood furnaces often sold for $ 1,000 – $ 2,000, less than many certified wood stoves. Even after the 2017 rules took effect, certified wood furnaces remain affordable with most selling for $ 2,100 to $ 3,200. Ten models are now certified, ranging from a more expensive European-designed pellet furnace at 89% efficiency to a very basic US Stove model 1330E that is 33% efficient.

However, the future of this class of wood heaters is far from secure, as EPA rules require wood furnaces to emit no more than 0.15 lbs/mmBtu as of 2020. Other than the European-designed pellet furnace, the other certified furnaces are not at all close to meeting that standard. Wood furnaces saw extremely little technological development until they were required to be certified between 2005 and 2017, and the sector is far behind the levels of controls that have been built into stoves and boilers.

Screenshots:


 https://hvacdirect.com/us-stove-1500-wood-coal-furnace.html 
 http://www.homeclick.com/vogelzang-vg1500-norseman-1500-sq-ft-wood-burning-add-on-furnace/p-878127.aspx

Heated Up!

Thermoelectric Wood Stove, Solar Power, and a Floating Cabin!


Guest blog post, by Margy Lutz

Finally this winter, our thermoelectric wood stove generator is fully operational. Following our test runs, we placed the pump to recycle cold water down in the lake water under the cabin. In winter, it gets about 5 degrees C (41 F). That’s plenty cold for a good differential between the 300 degrees C on the hot side.
Most system owners don’t live in a float cabin four feet with a constant cold water source under the floor. The typical user has to use a recycled liquid (usually including a water/antifreeze mixture) that runs through a radiator for cooling.
In addition, a charge regulator/controller is used to protect the batteries and prevent overcharging. The model that came with our system has lights to let you know the status of the charging process.

Wayne likes to know more about the charge we are getting. He installed an ammeter and a volt meter. The switch in the middle controls the water pump down below the cabin. To maximize the charge to our cabin battery bank, we’ve installed a separate solar panel and two six volt batteries wired in a series to run the pump.

Living off the grid has its challenges, but having an alternative power sources has made our winters much brighter (pun intended). Do you generate power? What are some of the solutions that have worked for you? — Margy

Postscript by Ken Adler, AGH Technical Advisor: 

Congratulations to Wayne and Margy on their thermoelectric wood stove. In a follow-up communication with Wayne, he reported that they are no longer using the system because the thermoelectric modules failed. Wayne doesn’t know why they failed, however, the most common reason for failure is overheating.  The modules can also fail if Bellville washers are not used to allow the module to expand and contract during heating and cooling. Wayne also reports,

Even when I was partially (marginally) operational, I produced less than 2 amps at 12V DC (23 watts) to recharge my cabin battery bank. This would have been enough to put a top-off charge on my cabin batteries (normally recharged via my solar system), particularly valuable in the winter when solar power is minimal and my wood stove is operating nearly 24-7. The primary reason for the low amperage was the need for a 1,8 amp 12V (21.6 watts) water pump to feed the cold side of the modules. In many ways, I reside in the perfect test location for this thermoelectric system, since 

I have a nearly infinite supply of very cold water 4 feet below my wood stove. I live in a floating cabin on Powell Lake BC, and the lake is extremely deep and very cold in all seasons. What an opportunity to serve as a source of cold water through the cooling system! The pump only needed to pump the cold water up 4 feet and then outflow back into the lake. Even with this tremendous advantage, I couldn’t get everything fully operational.

Does this make me a non-believer in thermoelectric from a wood stove? Absolutely not — I still believe this is an important future source of electrical power in my cabin, since even a top-off voltage during the solar-depraved Canadian winter would be worth the price. I’d be one of the first in line if a recreational property thermoelectric system was available, and I’d be quick to try again. Thus, I wish you all of the best with your preparation for the 2018 conference. I’ll be following the results closely.

In an earlier post, Wayne reports that he is using three 25 watt thermoelectric generators for a total rated power of 75 watts of output, however, he’s only getting 23 watts of power for his battery. Part of this is due to his pump, which is drawing almost 22 watts of power. If you are interested in building your own thermoelectric wood stove, there are a few improvements that you may want to consider. First, TEG suppliers (see our resourcespage) now sell more efficient lower wattage pumps. Second, consider starting with a thermoelectric generator rated for 100 to 200-watts. While this is more expensive, if you go with a smaller system much of your power will be consumed by the pumps and/or fans you need to cool the modules. Third, Bellville washers are critical for allowing the modules to expand and contract.

If you are interested in designing a thermoelectric wood stove for our 2018 Wood Stove Design Challenge, please visit our web sitefor more information. For more information on Wayne and Margy’s life on a floating cabin, please visit their blog at Powell River Books Blog.

For an overview of the potential of thermoelectric wood stoves, click here.

Heated Up!

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.
Currently, there are six forced air furnaces that are certified, 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 currently on the market, there is a huge 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 is the least efficient
certified furnace at 48%, but sells
for less then $ 3,000.

furnaces is 66%.

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.

Heated Up!