Manchester vs. Isle Royale vs. Cape Cod output...

[Woody Stover]

As usual, I'm confused by the output numbers on some of these big stoves. EPA rates the Cape Cod well below the Manchester and the Isle Royale, and of course manufacturer claims are totally different.
They are all pretty much the same size so I have to believe the outputs are going to be similar. The IR is the most radiant of the three, clearly.
Might be a while before someone runs all three and can report back.

 

[begreen]

Looking at the heat exchanger design of the top of the Manchester I wouldn't be surprised if that stove naturally convects the best without any blower needed.

 

[webby3650]

All these EPA tests are very confusing! Chris (BKVP) can explain all this very well. Maybe he will chime in. He explained it all to us and showed us how most all EPA tags on your new stoves give an efficiency rating and then In the fine print it says "not tested for effiecency" they just use the default number. So really, it shouldn't even have an efficiency rating a all! It's misleading to say the least. To my knowledge, Blaze King, Lopi Cape Cod, and most likely the Woodstock PH (I'm not for sure) are the only stoves that are publishing an actual efficiency rating.
Here is the tag from my ashford.

 

[BKVP]

OK I'll bite. There are default numbers (assigned by the EPA) for efficiency. Now the hang tag numbers for emissions are the actual number of what is called the weighted average of 4 different burn rates. Manufacturers do not take liberties with these numbers as they are reported by the test agency to EPA.

Now back to efficiency. As a manufacturer we can use the default (cats have slightly higher defaults than non cats) or we can use Thermal efficiency. The later was an option available to all manufacturers starting a few years ago. Few if any folks post their Thermal efficiency. Can you guess why?

To make matters a bit more confusing, in 2008, the original list of stoves meeting the 75% HHV (that's higher heating value) was very, very, very small....in fact they were all cat stoves.

So certain parties convinced the IRS to recognize the LHV (that's lower heating value) and miraculously lots (nearly all) EPA wood stoves qualified. Manufacturers had 3-4 formulas they could use to calculate LHV and they were permitted to choose the best result. Incidentally, self certification was permitted. Our company, and certainly a few others paid third party test agencies to calculate the numbers.

Both our company and my friends in NH had stoves that yielded numbers over 100%! Now how would that look on a BK or WS brochure.

If you go back and look at brochures from before 2008, you will find the efficiencies were 10-11% lower. No changes were made to most if not all the products but now they score high 70's and low 80's.

As most folks here know, the NSPS is in review and early on EPA wanted to create a minimum efficiency. They took too much heat (and rightfully so) so they have indicated the HHV number will be placed on the hang tag. No more default! I suspect the answer to why so few manufacturers report thermal efficiency will become very clear at that time.

Finally, you should never for a second accept any efficiency number other than Thermal or the HHV.

OK I'm off to get a bullet proof vest after this posting!

One final observation.... Our reps have reported that just a few manufacturers have been brazen enough to place their LHV on their gang tags. When this gets noticed by guys in suits, there is certain to be some discussions.

 

[webby3650]

Thanks for filling us in.

 

[begreen]

Thanks Chris, that's helpful information. I note that the BK results are according to HHV B415.1-92. Is this a Canadian CSA standard? Or is it the same standard used in the US?