Wait a minute It's true PE stoves are listed the minium EPA effeciencies 63%

Elk, The EPA doesn't test for efficiency. They arbitrarily assign the 63% rating to all non-cats, and the 72% rating to all cats. If a manufacturer wants an actual efficiency rating, he has to hire the testing done separately.

silly huh.

EBT - Schmee Bee Tee

Yup, Cat stoves are rated higher as the cats lose efficiency the longer they age and by EPA requirements must pass higher minimum standards to compensate for their getting progressively worse. It wouldn't be fair if they both had to pass the same minimum standards. The EPA compensates for cats getting worse as they age by calculating life cycles into the cats. That is, they expect a cat stove brand new to be twice as good as a secondary burn. In mid-life, the Cat & secondary burn should have the same emissions, and at end of life the cat should be putting out twice the emissions of a secondary burn. In the end, over the life cycle of a cat vs. secondary burn it should be a wash, but cats have to have higher starting standards to make that so. Also goes to say a cat stove passing with the lowest emissions recorded is irrelevant. I'd like to know what's the average efficiency or gpm's of a cat stove, I think it unfair they say what the starting value is as it's all down hill from there. In the end, it should be a wash with secondary burn units.

Even if a manufacturer tests for efficiency by an accredited lab, EPA will only allow the default 63% to be printed on the mandated EPA tag.

The EPA approved woodstove listing on their website is generaly updated about every 6 months or so. There's no real schedule but that's been the pattern the last few years.

EPA deliberately continues to list units even if they have expired dates because the old units still meet the test standards - the EPA standards have not changed for a long time. The unit's approval likely has been allowed to lapse by the manufacturer because the units have been discontinued. The expiration date really means that the manufacturer can no longer make the units unless they get them recertified.

With the multitude of fuels (woods) and burning practices is a difference of 10% anything to hang your hat on?

Does a 10% difference in the stated miles per gal fuel efficiency influence a car buyer? Similar principle, how many people actually get the mileage as listed by the manufacturer? Too many variablies in the real world so the best you can do is compare units (cars) in an artificial but consistent setting like a lab. It's a pity that EPA doesn't test for efficiency, then consumers would at least be able to compare units and say that (in optimal conditions) Unit B is 10% more efficient than Unit C but only 2% more efficient than Unit A and make an informed decision.

As I understand it, lower emissions doesn't necessarily translate to higher heating efficiency. Heating efficiency ratings are derived by testing both combustion efficiency and heat transfer efficiency.

To measure combustion efficiency, the fuel load is weighed going in, and the combined weight of the exhaust emissions and ashes remaining in the firebox are weighed after the fire. This part of the test determines how effectively a given firebox design breaks down the fuel to extract the heat.

A stove with a low particulate emissions weight but a correspondingly higher ash weight wouldn't score better in the combustion efficiency part of the test.

To measure heat transfer efficiency, the amount of heat extracted from the fuel (available heat) that transfers to the room is compared to the amount of available heat lost up the flue.

A stove with a low particulate emissions score but a relatively low heat exchange / exhaust temperature ratio wouldn't score better in the heat transfer part of the test.

This isn't to say that there aren't stove models that have low emissions and also have a low ash weight and a high heat exchange rate. I'm just pointing out that a low emissions rate doesn't necessarily indicate a high overall heating efficiency score.

So what is the score # that stove manufactures list on there stove ( xx% efficient )
Heating efficient in general (both ) ?, combustion efficiency ?, heat transfer efficiency ?

And, dealing with efficiency everyone has a different ability. Compare my wife and I, I can get my unit heated in about an hour, sometimes less and my fires produce miniscule amounts of smoke (just in the beginning) and raise my house temp anywhere from 8F-14F per burn. But, I've studied relentlessly and done countless experiments. I enjoy analyzing everything about how I load the wood, how to position the coals/ashes from the previous fire and how that affects the new, how the positioning of the wood inside affects air flow dynamics inside the firebox to maximize the path and turbulance before exiting, and when and how much to move the air handle. My wife, doesn't do any of that she throws the wood in haphazard, doesn't care about smoke, or how to position the wood to get the secondary burn going quickly, nor cares about the air handle setting for maximum burn & transfer efficiency. Her fires take twice as long to warm up, smokes up the neighborhood, and on average she gets the house warmed up 5-8F per burn, much different than my 8F-14F. I think one testing efficiencies & reporting is mostly testing how skilled the user is vs. the stove. So, I'm not sure stating efficiency or what a user can expect from their unit is applicable since, just in my household alone there seems to be a pretty big discrepancy and we're using the same thing. Though, I do like BeGreen's comment from a post way back, that is some units are finicky and others are not. A person that doesn't give two poops is not going to do well with a finicky unit and not get the satisfaction or efficiencies out of it, those with finicky units usually find them more enjoyable after the first year once they've learned just how their unit likes things done.

elkimmeg said:

They do list the grams polutants to compare. If stove A has 2.3 grams tha stove b has 4.6 i which stove given the same firbox size is more effecient? the one that does the best job of burning up the pollutants turning that into heat /energy.

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I don't discount what you're saying, but once we get down to these low emissions levels, I wonder about it. With, as you say, a 15 lb. fuel load, a couple grams is not very significant, is it? And shouldn't they state the results as a percentage of the fuel load instead of an absolute number? That would be a better measure of combustion efficiency.

The Btu EPA test are only for the same said amount placed in every firebox so that cannot be used a huge fire box with 15 pounds of wood does not indicate total BTU production

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The amount of wood used in the test changes depending on the size of the firebox, so comparisons are only fair within the same size category.

The EPA compliance testing gathers MUCH more data than is required to be published. I really wish they would give us access to more of it. The really useful stuff is kept hidden.

[quote author="precaud" date="1170278677"The EPA compliance testing gathers MUCH more data than is required to be published. I really wish they would give us access to more of it. The really useful stuff is kept hidden.[/quote]

I have a few different older revisions of the B&W Steam Book.
http://www.babcock.com/pgg/tt/steambook.html

They have some examples of test reports and there is no way the data could be boiled down to one number that had any real meaning.

By the way the older revisions of that book have a lot of data in them and burning stuff, that can be applied to stoves like we use, the newer ones have dropped some of that date and concentrate more on very large furnaces burning powdered coal and of coarse nuclear stuff.

BeGreen said:

Our old 602 seemed to have fantastic heat transfer efficiency.

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Yup. That's because, except for those two "burn plates" that hung on the sides, the stove was completely uninsulated. That's what gives high transfer efficiency - a flame path unobstructed by insulation or air channels.

It may sound nuts, but in terms of wood in -> heat out, the Morso 2110 I'm burning now, ythough it is nearly twice the size, is only marginally better than the old 602 when burned hot. The new F602 burns cleaner but, with 50 lbs of insulation, much more heat goes up the stack.

Roospike said:

So what is the score # that stove manufactures list on there stove ( xx% efficient )
Heating efficient in general (both ) ?, combustion efficiency ?, heat transfer efficiency ?

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I can't answer your question, but here's an example. These are the data sheets that came with the Quad 2100M.
Frankly, I don't believe the EPA numbers.
Smoke of 2.1 gms/hr. But the Morso 2110 at 4.5 gms has less visible smoke out the chimney over the whole burn cycle.
We already know the assigned 63% efficiency number is meaningless.
Heat output rate range of 11k - 37.3k btus/hr. I defy anyone to get this stove to burn as low as 11k btus/hr cleanly. This stove wants to burn hot. And 37.3k tops? I say that's low. They tested the Morso 2110 at 42k btus/hr max and I know the Quad stomps it.
So these EPA numbers are suspicious at best and useless at worse.

BUT... the overall efficiency number on the cert that Quad furnished with the stove corroborates my experience with it. For wood input -> heat output, this thing is sick. (That's what my son sez when something is unbelieveably good.) Compared to the Morso, which is about the same size and I considered to be no slouch, the 2100M keeps my house warmer and uses less wood doing it. Period. Judging by the amount of wood needed to keep my inside woodbox full, I'd estimate the Quad is about 20% more efficient overall. That's a significant amount. Needless to say, I look forward to having it back on the hearth next winter!

But.. the point of all this is... the EPA numbers don't tell us what we need to know.

Is anyone familiar with the "Oregon Standard Efficiency Methods" from 1984 that Quad is quoting?