I have a feeling that this one is "some or all of the above" including the customer expectation, the weather, the lighter (and possibly faster heating) of the older stove, etc. etc. .....I think the dealer replaced the entire board (earlier in the thread?). It would seem that computer control and sensors would pretty much be able to "know" if something was vary wrong....i.e, if the exhaust was VERY hot, it would shut down the stove? Confusing, for certain. GVA, too much heat coming out the stack and too little heat could mean the same thing! What I mean is that if the exhaust pressure (flow) is low, then it might be too hot, if it is way too much air coming through the thing (excess air), then it is low. BTW, back during those old "in the field" tests, it was "excess air" which caused the low numbers of most stoves! The combustion numbers were fairly good.....but too much air (even at a low temp) ends up sending BTU's up the stack. As is probably obvious, I am just poking around with these theories.