Well, a failing door gasket would provide an excessive amount of combustion air into the fireplace. That's what a dollar bill test would be designed to demonstrate, I presume.
That is presumably causing more fuel to be consumed, but heat recovery per unit of fuel to go down = efficiency of the stove low.
I'm guessing that a combustion analysis might find that the oxygen level too high and the CO2 level low in the flue gasses. Low carbon monoxide reading reflecting the ease with which the CO is burned in the bright fire and abundant oxygen. Those readings and a low stack temperature would point to excessive combustion air through the stove, but not the cause of the problem. Normally oxygen levels should be low and carbon dioxide levels high indicating that combustion has effectively taken place in the stove, turning oxygen into carbon dioxide. Draft pressure low because the stove is being flooded with combustion air?
Presumably the stack temperature would be low, or perhaps moderate, reflecting the excessive combustion air going up the chimney before the heat produced from the fire can be absorbed by the stove and radiated into the room air. The bright fire and rapid fuel consumption would be symptoms of that excessive combustion air, and shutting off the stove's air supply is another effort to reduce that excessive air flow. through the stove.
Shutting off the regular air flow into the stove should cause what? High levels of carbon monoxide as the flames are strangled for lack of oxygen and heat to complete combustion. That's sure! Low oxygen levels. Perhaps low carbon dioxide. Stack temperatures low reflecting poor combustion, headed down to a fire going out. Draft pressure high at the stove pipe above the stove.
The window gasket is certainly a likely culprit, but if it were found to be OK, something else would presumably be causing excessive draft through the stove. In short our experience stove techs have identified
It seems our stove techs have identified the likely cause of the problem and a useful way to test their theory. Combustion analysis would likely point to excessive combustion air as the problem, but not what is specifically causing that problem.
But suppose the window gasket were found to be A-OK? What then? Could something else cause these symptoms? If so, what?
<<If the gaskets are sealing well, try burning larger splits and turning down the air much sooner. Don't wait 30 minutes or for a high stove top temp before turning down the air. Turn it down as soon as the wood is burning well and turn it down until the flames start getting lazy. Then wait for 5-10 minutes for the flames to regain strength and secondary combustion begins. Then turn it down again until the flames get lazy. By turning down the air aggressively the wood will outgas slower. This helps reduce the peak spike in temperature and extends the burn time.
I see Bgreen has a possible answer to that question. Still excessive combustion air as the problem, but a different way of operating the stove to make it work better, is how I'd characterize his recommendations.
Manly
