So Which stoves are the cleanest burning stoves?

[seaken]

I do get quite a bot of talk about efficiency and GPH with the folks who visit our store. It is on the minds of people, perhaps more than some here anticipate. But, I do tend to agree that the published numbers should not be used for more than comparison purposes. I say the same thing about the BTU numbers as published, or the square foot numbers. These numbers are all over the place and are misleading in the hands of a novice. It takes a lot of study and detective work to sort it all out so that it makes sense. We discourage taking all these numbers too seriously. However, if asked I will fully explain the meaning of the different numbers and, in the process, help the prospect make an informed decision. If they want to buy by the numbers that's okay. But most understand that the real numbers are far more unpredictable and depends mostly on how they use the appliance and how well they adjust to the different variables that effect the overall efficiency of their stove.

As far as pellet stoves being more efficient and less GPH. Maybe. But again, it depends on who's using it and what they know about how to get the most out of the stove. There is still a lot of variability in these appliances. Until these appliances get more sophisticated they will still be largely dependent on the user for the overall efficiency they are capable of. I suspect a device may exist that only produces water vapor after burning a solid fuel. But it is not in the consumer market. (NASA maybe?) Consumer appliances for solid fuel are still only capable of about 75 to 80 percent efficiency. This can be achieved with almost any modern appliance in the right hands, whether wood, pellet, corn, or coal. They can also be turned into disgusting smoke belchers in the wrong hands.

Didn't we see a positive result in Montana where old stoves were changed out for new stoves (EPA certified) and the air quality in the valley improved dramatically? Seems that could be used to back up claims of cleaner GPH stoves being of high value. I think the message to the regulators has to be that the new appliances have a much better chance of burning clean than an old pre-EPA stove in the hands of the normal user.

Sean

 

[Todd]

Cast, the last time we beat this horse I made the point that if stove A tests cleaner in the lab than stove B, it is likely that stove A will also burn cleaner than stove B out in the real world. So yes, to a point the GPH numbers are relavant to the real world.

OK, Griz - please see enclosed chart, take the cert numbers and the real world numbers and tell me if they are related in the way you say. If they are not, then let us know if you stand by your statement above, or if it was just a guess.

A quick scan shows absolutely no relationship!

Example: PE - certified at 3.x, runs at 4.x
Earth stove certified at 3.x, runs at 15.x
VC Encore cert at 1.x, runs at 20.x
Haughs cert at 4.x, runs at 2.x

So I guess if we want to say that numbers could be off by a factor of 20X or more, we might be getting closer to reality.

Please show or argue SOME factual basis for thinking that cleaner in lab = cleaner in field.

To be fair these stoves needed to be set up per manufactures specs, and they aren't. For example the VC Encore only had a 8' chimney. That's about half of what is recommended and probably is the cause for the poor performance. Also who knows what the burning habits were during this test?

 

[jqgs214]

ah, but thats the "real" world, not some made-up, eveybody gets a permit and inspectyion and it is set up to manufactueres specs.

sad but true

 

[elkimmeg]

Craig are you still trying to use such an unscientific sampling riddled with holes to draw a conclusion with?
The same study Ny soapstone and others members buried on BI You know the only control in that sampling was that there was no control

This study is based upon 1992 and 1993 stoves. Not one stove had everburn type technology of today with .7 GPH Last time I checked the calender it was 2007?

Hell the cat stove the study never confirmed its condition at the outset never confirmed if gaskets were in good repair never confirmed if the stoves received any mantiance ,

Never confirmed the quality of the wood used or moisture content Talk about basing a study without confirming any of these variables and you want to hang you hat to disprove a
reconized lab controlled certified testing.. And What about the lack of sampling numbers. 16 stoves represent that state of used stove burning. None educated by hearth,com as to good burning practices and techniques. Come on web this is so outdated so un scientific why wast you time on it. This was promoted by Omni labs. The same labs their PHD wrote this article in 2006.

Really you are beyond stretching the imagination here Why not read the 2006 version from the same people Omni also admitted the short comings of this study Why not publish this as well.

The only real valid conclusion from this study was that maintained stoves preformed better than neglected ones and some equal to or better than newer models

IT is possible my stoves equipped with after market superior Cat combustor exceed the original GPH's How would you factor that into this equation?

the cat encore in this study the 20x worst had no record of its cleaning or mantaince We here at Hearth.com know the importance of mantiance and would never have a cat stove running 5 years with never having cleaned it.

 

[BrotherBart]

As long as the largest variable in stove performance relies on which chunk of stored energy I grab off of the top of the woodpile the numbers will remain useless in everyday operation.

But it is still nice to know what the stove is capable of in the hands of a knowledgeable person with standard procedures and fuel loads. That is why I wanted to spend more time with Bob in his lab at England's Stove Works but didn't have the time. I would have liked to had his views on the optimum operating procedures for the 30 that he used in his in-house cordwood tests. I suspect though that his best results were achieved at operating temperatures that I ain't gonna replicate on purpose. He gets replacement stoves for the lab free. I have to buy my replacement stoves and houses, and heft the stoves in and out.

 

[webbie]

Exactly - these stoves were probably "better" than many since they would not have included any in the study with clearly defective setups. That would have opened them to lawsuits from the manufacturers, etc.

This, to my knowledge, is the ONLY scientific study of it's kind which is complete....it is 70 pages!

Any way you slice or dice the data, it does not make up for the differences. Also, keep in mind that EPA tests are done with a certain chimney setup, and not (to my knowledge) to an specified chimney as per the manufacturer.

The real world has real wood with real moisture contents, with real chimneys and real operators. Also real weather, real altitudes above sea level and various amounts of combustion air (depending on location of stove in house, construction, etc.)

You can NEVER remove these variables....which is exactly what we are discussing. So to make an accurate statement:

"The only scientific field test done on EPA Phase II certified stoves in home settings shows no relationship between certified values and actual stove performance"

And another:
"EPA stoves do not work as well in the field as they do in the lab".

That is what the data shows. So either we need some more data, or we are simply blowing smoke out our chimneys to claim one stove is cleaner than another.

 

[seaken]

Craig are you still trying to use such an unscientific sampling riddled with holes to draw a conclusion with?
The same study Ny soapstone and others members buried on BI You know the only control in that sampling was that there was no control

This study is based upon 1992 and 1993 stoves. Not one stove had everburn type technology of today with .7 GPH Last time I checked the calender it was 2007?

Hell the cat stove the study never confirmed its condition at the outset never confirmed if gaskets were in good repair never confirmed if the stoves received any mantiance ,

Never confirmed the quality of the wood used or moisture content Talk about basing a study without confirming any of these variables and you want to hang you hat to disprove a
reconized lab controlled certified testing.. And What about the lack of sampling numbers. 16 stoves represent that state of used stove burning. None educated by hearth,com as to good burning practices and techniques. Come on web this is so outdated so un scientific why wast you time on it. This was promoted by Omni labs. The same labs their PHD wrote this article in 2006.

Really you are beyond stretching the imagination here Why not read the 2006 version from the same people Omni also admitted the short comings of this study Why not publish this as well.

The only real valid conclusion from this study was that maintained stoves preformed better than neglected ones and some equal to or better than newer models

IT is possible my stoves equipped with after market superior Cat combustor exceed the original GPH's How would you factor that into this equation?

the cat encore in this study the 20x worst had no record of its cleaning or mantaince We here at Hearth.com know the importance of mantiance and would never have a cat stove running 5 years with never having cleaned it.

I think I'm mostly with you Elk. But I think the point that others are making is that this lack of maintenance is in fact the real world. We have found this to be the case in our own business. We have learned to be careful before placing a VC Encore in the hands of person who has no inclination towards maintenance. Same with pellet stoves. We'd rather sell a non-cat box stove or a gas stove to someone who just wants it to be easy and doesn't want to be bothered with a little cleaning now and then. Fact is, most of our customers don't really understand their stove. ANd for some people selling them a VC Encore was a mistake. For others, it is perfect. It depends on who is using the stove.

But I'm with you on the GPH theory and I think it is important to continue to push the envelope and try to get cleaner and cleaner. Unfortunately, the average consumer wants cheaper and easier. Sometimes there is just no room in the market for advanced technology. But take TARM as an example. Most consumers think they are too expensive and would never buy one. But they have carved out a market and sell their stuff to those who appreciate it and have the money to spend.

Sean

 

[jpl1nh]

I think the point here is getting blurred. The GPH numbers the ExACT numbers, dont mean doo doo but the fact that the % of particulate relased to the air has dropped considerably over, the years does!! So in my mind the GPH #'s matter and yet they dont. (DEPENDS ON WHY YOUR USING THEM I GUESS) When you get down to 2.0, 4.0, 1.64 they all burn clean but to buy a stove because its 1.64 your a fool. BI needs to know that burning wood is a clean practice now. Which when DONE RIGHT is!

I have to completely agree with wxman, (even though his degree says he's a weatherman) When talking with BI and others concerning particle release, the real news is that particulate release from an EPA approved stove today is probably as much as 35 gph less than the pre EPA era stoves! From what?. 50gph to 1.6 or 6.2 or 3.4, whatever! That is what is important. Yeah I'm proud to have a Woodstock cat stove with great gph numbers but I don't think the people I bought it off of even knew how to use the cat since the space between the ash screen and the cat was PACKED with ash!! They obviously were'nt getting 2gph!! When you look at the reduction of 30-40 gph the idustry accomplished in the last 20 years, the efforts to boast about an additonal gram or two don't seem like much.

 

[stoveguy2esw]

the testing done for epa certification is done to provide a guideline for applying a standard for the industry for acceptable emmissions. personally i do not believe the standard was set up to give "real world" numbers but to establish how "relatively clean a unit will burn in a normal situation. to be able to establish degradation over time a unit would have to be tested over that time which is extremely impractical. to test new stove "real world" emmissions the unit would have to be tested with multiple wood species at various moisture contents. also not very practical. the standard of using the same charge of wood and the same flue overpressure as the "control' for the test with the stove being the variable is as fair as the test standard can be for practical purposes. if using a ful load of wood (such as a customer would use) the "control" of the same size charge of wood would be eliminated as different size fireboxes hold different amounts of wood. this would result in the testing standard haveing to carry a seperate test standard for literally every size firebox imaginable, it would no longer be a "standard".

all that said, the GPH ratings are determined by the charge of wood that the testing agency uses, not "real world use" but it does allow a comparison on as level a playing field as the EPA has managed to come up with.

as a note also , the smaller the firebox is , generally the easier it is to get a stove dialed into a cleaner burn which is why there are more less than 2.5 CF units in the "hall of fame" than larger ones.

 

[jqgs214]

Elk,

I agree with you that holes can be poked into that study left and right but unfortunately the "real world" never conforms to a study which is exactly what I take out of this study. Its not a knock on the VC, it just shows that "real world" burning differs greatly from EPA testing and in the real world excellent results can be had with little effort and terrible results can be had if that effort is not put forth.

 

[Gunner]

To be fair these stoves needed to be set up per manufactures specs, and they aren’t. For example the VC Encore only had a 8’ chimney. That’s about half of what is recommended and probably is the cause for the poor performance. Also who knows what the burning habits were during this test?

EXACTLY.... That is the real world. There is no point in doing another "perfect senario" test, we already have those numbers from the EPA.

 

[webbie]

I guess when you don't have real data, just believe the brochure?

I would not make a buying decision from either the real world testing nor the brochure numbers. I would look for user experiences...and other factors such as where a stove is made, etc. - Western stoves - even with cordwood tests - often use softer woods. In the Mid-Atlantic and south we use dense oak - in New England, a mixture of many mid-level hard woods.

We have beat these subjects to death a number of times. Omni admits cat stoves degrade quicker in performance....so if I bought a cat stove I would look HARD at the construction and bypass mechanism.

I think we all agree yet are saying it in different ways. That is "a number of factors affect stove performance MUCH MORE than Epa tests". No one can dispute that. In fact, that is the big problem with OWB - the stumps with dirt on them, the tires, the green wood and all the other junk.

Perhaps in the future we will have "burners licenses", and make our subjects take a test on their pyro abilities.

Are there possible advancements? Yes, certainly they have tuned up the old downdraft setup....and initial reports are hopeful. But until we see what 5+ years of burning does to the liners, castings and stoves, we cannot even say if those improvements will result in cleaner stoves over the long run. I would hope that stove makes learn from experience- but then again, there are few common (and cheap) materials that can hold up to the 1500 degree plus created by the downdraft systems....combined with the shock of throwing wood in the things.

I guess the Elk-Issod test lab is gonna have to do destructive tests in addition to operation and emissions. I LOVE destroying stuff!

 

[MrGriz]

Cast, the last time we beat this horse I made the point that if stove A tests cleaner in the lab than stove B, it is likely that stove A will also burn cleaner than stove B out in the real world. So yes, to a point the GPH numbers are relavant to the real world.

OK, Griz - please see enclosed chart, take the cert numbers and the real world numbers and tell me if they are related in the way you say. If they are not, then let us know if you stand by your statement above, or if it was just a guess.

A quick scan shows absolutely no relationship!

Example: PE - certified at 3.x, runs at 4.x
Earth stove certified at 3.x, runs at 15.x
VC Encore cert at 1.x, runs at 20.x
Haughs cert at 4.x, runs at 2.x

So I guess if we want to say that numbers could be off by a factor of 20X or more, we might be getting closer to reality.

Please show or argue SOME factual basis for thinking that cleaner in lab = cleaner in field.

Craig, I wouldn't call it just a guess. I would call it more of an expectation. Not to mention if you read the quote you are referring to, I said "it is likely that...".

In my mind, your chart only proves the point that certification numbers are useless. Doesn't it? I assumed (I know that's dangerous) that a stove which tested lower in the lab would burn cleaner in the real world. I would think that most people would make that assumption. After all, I am not a stove expert by any means, I am just a typical stove consumer.

This brings up a good point. If the average consumer is using lab test data to make their "informed" decision on which stove to buy, they are basing the decision on a fallacy. That would suggest that they would choose the VC Encore from your list, thinking they were buying the cleanest burning stove they could. Just imagine the look on their face at the cocktail party when they boast about their clean burning practices in front of the guy with the Haughs who then pulls out this study. That's one VC owner with egg on his face and tears in his cocktail.

I still don't believe that a large percentage of consumers pay close attention (if any) to GPH numbers when choosing one stove over another. I'm sure some do, but I would suspect that they are in the minority.

 

[jqgs214]

and Griz, I suspect your right about not many looking a GPH numbers but the ones that are probably will do their best to make sure its burning as cleanly as possible (just speculation) and then your theory would hold true that the cleaner epa stoves would test cleaner in the read world. Biggest problem with that test is the small sample size, like to see 10-20 vc's and average them out. Look at the pe 27'S 2 DOWN AROUND 5 AND ONE AT 15. Oops sorry for the caps.

 

[MrGriz]

wxman, I have no doubt that those who look at the GPH numbers are the ones burning cleanest in the real world. I would suspect that anyone who looks that closely at GPH is also looking into all other aspects of the design, construction and use of the stove much more in depth than the average person. That would lead you to believe that they are also looking closely at their installation, environment, fuel and burning practices in order to maximize every area. Of course I can't back that belief up with a study so I'm not sure.... ;-)

 

[jqgs214]

Case in point, my mother bought a quad freestading stove 10 years ago. Had it installed, never permitted, never once put a thermometer on the thing, too my knowledge never once overfired it, burns the punky wood at the bottom of the pile, some christmas wrapping paper to start a fire (makes cool colors btw) and she couldnt be happier with its output, performance or anything. All she knows is it keep her and the cats warm. Btw, she burns mostly oak and when i see it burning its not putting out smoke so at least she's doing something right. She had the chimeny swept 2x in 10 years and took about a quart of stuff out each time. Internal central single wall pipe. Even the uneducated (and cavemen) can do it right Hogz?

 

[Henz]

Avalon

 

[jjbaer]

I still say that you can throw the actual test emission numbers out the window in the real world because no one burns like the tests are conducted and no one is going to consistently achieve (if ever) the emission numbers that the labs do. For one thing, the tests aren't even conducted with cord wood.

You say you understand it but your words say otherwise.......the very fact that a stove will be used in a non-EPA certified manner means that unless you have other data, you must use what common test data you do have and that means using the original EPA test results.....

 

[jqgs214]

Cast_

Last time I checked there where no regulations by the EPA on the "USE" (the actual day to day operation)of a woodburning stove. They only regulate that stoves manufactured to their specs can be installed. The EPA never wrote a lick of installation code to my knowledge. Who misunderstands??

 

[jjbaer]

Cast, the last time we beat this horse I made the point that if stove A tests cleaner in the lab than stove B, it is likely that stove A will also burn cleaner than stove B out in the real world. So yes, to a point the GPH numbers are relavant to the real world.

OK, Griz - please see enclosed chart, take the cert numbers and the real world numbers and tell me if they are related in the way you say. If they are not, then let us know if you stand by your statement above, or if it was just a guess.

A quick scan shows absolutely no relationship!

Example: PE - certified at 3.x, runs at 4.x
Earth stove certified at 3.x, runs at 15.x
VC Encore cert at 1.x, runs at 20.x
Haughs cert at 4.x, runs at 2.x

So I guess if we want to say that numbers could be off by a factor of 20X or more, we might be getting closer to reality.

Please show or argue SOME factual basis for thinking that cleaner in lab = cleaner in field.

Craig,

were these stoves tested in their various owners homes (in which case they were each operated under different conditions) or were they removed from the owners homes and hauled back into the lab?

 

[karl]

What is the big deal with all of this? Old stoves smoked alot and used alot of wood. The EPA got involved and made the manufacturers improve their stoves. Now, new stoves don't smoke much or any and they use much less wood. It sounds like a great improvement to me.

Who care's about few grams an hour?

 

[jqgs214]

Cast-

read the report

 

[jjbaer]

ah, but thats the "real" world, not some made-up, eveybody gets a permit and inspectyion and it is set up to manufactueres specs.

sad but true

wxman,

.....no problem with "real world" but what the person is saying is that some of these stoves are not being tested using conditions that their manufacturers say they need to be operated in, such as flue size, etc. (you're not comparing apples to apples) whereas with EPA testing you are operating the stoves per each manufacturers requirements.....

 

[jqgs214]

But this is as real a test as you can get- just not enough sample size. It clearly shows that somes stoves can burn as cleanly at they are tested by the epa and some cant (under the conditons of this test) and it does all depend on the set-up which are all going to be different.

 

[elkimmeg]

The EPA never wrote a lick of installation code to my knowledge.

This is not so much a comment on this issue, but it reminded me that every certified owner's manual has to detail how to opperate the stove, how to maintain it.. This is required as part of the certification and listing Point being One has no leg to stand on when they use wet wood never manitains it or acts dumb in opperations. This being so there should be very little stoves out ther to test is such poor conditions