EPA efficiency rating

[Beno]

I wonder, how come all the non-cat wood stoves have 63% efficiency and all the cat wood stoves have 72% efficiency? Do all the stoves have equivalent efficiencies?
http://www.epa.gov/Compliance/resources/publications/monitoring/caa/woodstoves/certifiedwood.pdf

Thanks!

 

[Todd]

Just a default number the EPA came up with for the 2 different types of combustion stoves, cats and non cats. Manufactures do their own tests through independent labs to get better numbers. As they say your mileage will vary.

 

[Beno]

Can I trust the manufacturers "independent" tests? They seem to be always well above the epa.gov numbers.

 

[Todd]

I don't trust either. They test in ideal conditions, and tweek everything til they get good numbers. Not the real world.

 

[Beno]

Is it safe to say that 2 cast-iron wood stoves both cat or non-cat having the same firebox will give about the same amount of heat, in similar conditions? And a cat will give about 10-15% more heat (or longer burn time) than a non-cat? I compare VC cat Defiant with PE Summit, both have about 3 cu.ft. firebox.

 

[begreen]

Not necessarily true. Some stoves of similar capacity and material will perform quite differently depending on firebox shape, baffle design, etc. Also note that some non-cat steel boxes are burning as low as 1.1 gms/ hr, where others of the same size are at 4+ gms/hr.

 

[webbie]

In my opinion, EPA numbers should be looked at as "pass-fail" only - and manufacturers numbers at the same. We have discussed this many times before, but there has only been one set of documented field tests done on EPA stoves. In that test, stoves did not perform anywhere near their numbers! The conclusion of both EPA and the Test lab experts (to date) is that EPA results are not a predictor of long term stove performance.

More specifically, a NEW stove (before any part has degraded) into a 15 foot straight up insulated chimney and using well dried pine firewood - just might perform somewhat in keeping (relatively) with EPA numbers.

My general suggestion is to use firebox size - with the slight caveat that in smaller stoves a catalytic may add to the ability to turn the stove down (longer burns)...... do some searching around here...there are LOTS of older conversations about this.