I don’t know how many people are actually advocating stoves be “sealed”. Modern stoves are highly engineered to add a specific amount of air in theory to balance good burn time with achieving as clean a burn as possible.
So you mean they are calibrated to have the right minimum amount of air when at fully closed setting?
Some people try to block the “boost air” port that enters the stove to limit air this way. However, this is just one of the locations that air gets in to the stove- you still have the primary and secondary air intakes.
Hmmm. I would not do that. I understand people want a long burn, but I like a clean burn.
BTW , how did you “seal” your stove?
It is something people talk about on the forums. I did not say I sealed mine. I suppose did "seal" the small Jotul by taking it apart to clean it and putting new cement on the seams when putting it back together. I did not block or modify any air intakes.
IMO, the important thing with sealing is to get the air to go where it best contributes to combustion. A non catalyst stove needs combustion to get up to 1200 degrees minimum with adequate turbulence to start to combust CO (most shoot for 1300 to 1400 degrees). The only way that happens is by preheating fresh secondary air full of oxygen that is injected into the hottest part of the primary flame and that usually requires that the air goe through tubes or castings exposed to flames to heat it up. Air goes the path of least resistance so if it is a leaky stove the air just skips the secondary air system and the peak combustion temp never gets high enough to burn CO. It goes right up the stack which is the equivalent of throwing away every 4th piece of wood. That is the primary reason modern stoves are that more efficient.
I'm sorry I asked.
Hahahaha, no, actually this is great. It makes sense and does explain why one wants the seams to be air tight to the extent possible, and the air to flow in particular places.
1200 degrees? As opposed to only 500 degrees needed for a catalyst? I wonder if that explains why I feel I can engage secondary combustion on my cat stoves much sooner than I can on my non-cat stove.
This is most important when the stove is trying to be turned down, at full load unless the wood is wet combustion temps do tend to get over 1200, but once someone tries to reduce the output, a leaky stove is going to pull in air from the wrong places and actually cool the flame temp.
I used to think, who cares if the air pulls in from the "wrong" places... just turn down the air intake more. It does not matter where the air comes from. But now I see how it does matter for an EPA stove trying to achieve secondary combustion.
A catalyst drops the ignition temp of CO so that it burns at lower temps so secondary air is (or was) less important. The new EPA stoves in order to meet the standards have to be very careful where the air goes and turn down is more of challenge. People tend to buy one stove which is typically very oversized most of the heating season and then try to turn it down.
This is why I have two stoves - a small iron for shoulder season, a large soapstone for longer burn or when it is colder, and then I can run both stoves when it is brutally cold outside.
Running turned down can lead to low combustion temps so one of the tricks is have hidden secondary air inlets not controlled by a damper so that the stove cannot turn down. The stove owner will complain that the stove will drive him/her out of the house but its actually doing what its supposed to do. The approach with those type of stoves is to burn small fuel loads hot but that means shorter burn time. If you follow the forums on occasion folks will post how to block the secondary air ports on various stoves to make them turn down more. Effectively they are voluntarily dropping combustion temps and turning their new stove into a "smoke dragon".
Sneaky. But I am not a fan of turning stoves way down to smoulder and get everything dirty anyway.
A lot of the issues with a wood stove and even older wood boilers is they depend on natural draft and every installation has a range of drafts so sometimes the stove installed is outside the range it was designed for, most folks buy new stoves in the summer so when fall rolls around they are trying to learn how to burn in the toughest conditions where the outdoor temps are not that low and the owner wants low heat output and there wood is probably not that dry. Thats when more experienced folks sometimes get a deal on almost new stove when the original owner gives up
That is a triple reason why early fall is a difficult time to burn. It was not the time to use the Woodstock Fireview! But I wanted to test it out. I should be using the little Jotul (which I have running right now).
BTW the big biomass power plants I used to tune dont depend on natural draft. They have a big (500 HP) induced draft fan that pulls the combustion gases through the boiler and the downstream equipment including a big air preheater (heat exchanger) and then pushes it the gases up the stack. A separate forced draft fan takes in outdoor air and runs it through the other side of the air preheater and then air is injected into the boiler where it can do the most good. Because its pressurized it when it gets to the boiler it also can reach farther into the flame as the combustion zone of a small biomass boiler may be 20' wide by 40' deep. I also needed to worry about NOx formation that happens when the temps get too high, (above 2200 F). Home stove owners do not have to worry about NOx.
Some home wood boilers would not meet the new EPA regulations until they added forced draft fans and even prior to the new EPA regs some designs like my taarm solo plus included forced draft fans. Anyone with pellet stove is quite familiar with blowers as its an easier way to get a clean burn but I suspect that most wood stove owners would object to having to plug in a blower to run their stove.
This is interesting. One has to them burn fuel of some sort converted to electricity to run the fans. I suppose it is still a net gain?
Well, now I see why sealing seams on an EPA stove can be beneficial. But what about my old antique, completely unsealed stoves? Would my rationale hold that it does not matter where the air comes in on those stoves? They are basically an iron box with a sliding plate under the door to sort of somewhat control some of the air flow (while a bunch of air leaks in from many other places).
