Efficiency discrepancy?

[Redbear86]

I noticed that the EPA lists just about all stoves with a cat @ 72% efficiency, and all the stoves without cats @ 62% efficiency which is about (at least) 10% discrepancy from what the individual companies advertise, any comments/explanations?

 

[stoveguy2esw]

those are "default" when geting a stove certified a manufacturer has option of paying a lot more for an "actual" rating or accepting default which is the minimum. doesnt mean the stoves all burn at that efficiency, but they were tested to at least that and in most cases a bit higher

 

[Redbear86]

That makes sense. Thanks for clearing that up- so checking the epa ratings for the efficiency of a stove thats out of production wouldn't be accurate! Looking to see what the efficiency is of a lopi 380-400 think its was the first model year or so.

 

[Hass]

don't forget there's burn efficiencies and heat transfer efficiencies... make sure you're looking at the one you're after.

 

[Martin Strand III]

don't forget there's burn efficiencies and heat transfer efficiencies... make sure you're looking at the one you're after.

Actually, there's a bit more to it than that. To know the actual heat that is transferred from the stove to the room, one needs to know the
COMBUSTION EFFICIENCY which is high(90% or more) for most new stoves and the
HEAT TRANSFER EFFICIENCY (THERMAL EFFICIENCY) which depends on the thermal mass of the stove, how much heat escapes through the chimney.
Know these two efficiencies, multiplied together and you get the
OVERALL EFFICIENCY.
Sorry, but there's still more.
Wood stoves differ in their ability to store heat and, thus, must be dampered down to prevent all the heat from the fuel escaping into the room in a short time and overheating the stove. This is the
LINEARITY OF OUTPUT of a stove which varies with its mass. Then, at last, there is the
PARTIAL CHARGE EFFICIENCY which is the ability, or not, of a particular stove to handle a small fuel load 'efficiently' without smoldering. This is important in off season days.

So, when a mfg puts out an "efficiency" number, it really does not have much meaning. Buyers would spend their time much better choosing a stove that appeals to them esthetically, is sized properly for their application and has a dealer with some integrity who will guide the person in the right direction, charge a fair price and stand behind the sale if problems develop.

Aye,
Marty

 

[Redbear86]

Thanks Marty S.- sounds great! Someone like me would probably need a pie chart to understand that..... mmmh.. pie...... lol- my main question about this stove was whether or not the endeavor was a lot more efficient than the 380-440 or just cleaner, it seems the main difference is that the endeavor has two secondary air supplies while the older model had only one.

 

[Martin Strand III]

Maybe it's not obvious that most newer stoves burn cleaner than old ones; Phase II v pre-phase II.
Then there's the cats v the non-cats for 'cleaner', more 'efficient'...
An argument can be made for 'cats are cleaner' but they require fussen' which turns a lot of folks off.

The bottom line is go with what you like, burn safe, hot and clean since it's not the stove that will make
the difference in the end - it's you, the operator.

Aye,
Marty