Not sure what you mean by the seal. My OWB has a firebox door with gasket and an outer door with a foam seal. With my Heatmore furnace it operates best when minimal outside air gets to the firebox when the blower is off. If air is leaking into the firebox then the wood is still being supplied with what it needs to burn. If the seals are doing their job then the fire dies down to just a wisp of smoke coming from the stack. When I say a wisp I mean a small wisp of smoke, about as much as a man with a pipe. When the water cools down enough to kick the blower on then the fire comes to life again. Thats how mine works anyways. the seals are very critical in the Heatmore furnaces IMO. I clean the ARD door gasket and Blower motor gasket once every two weeks to keep the creosote levels down so that the unit seals well when the blower is not running. If mine leaks too much air into the fire box the fire will continue to burn and the water temp could go up too high. I have seen other brands that are not so sealed and are not designed like the Heatmore. Some seem to spew smoke all the time indicating they are getting some constant air to the firebox. If your seal is bad then your fire is burning more than it should all the time and that means your going to go through more wood I would think. That being said though I would think your water temp would stay pretty constant being that you have a fire going pretty much all the time. Get the manual on your furnace or call a dealer for your unit and get the scoop on how it supposed to work. There are differences between brands and how they were designed to operate properly.
