My house is fairly leaky, but haven't tried burning with a window open. The folks at chimneysweeponline.com thought that adding the outside-air kit might solve the back-puffing problem.Todd said:It's a good possibility if you have a negative pressure problem. Good way to check is to burn the stove with a nearby window open to see if it corrects the backpuffing. Does your Defiant have a thermostatic coil? Maybe it's stuck or broke?
Gridlock said:Could installing an outside-air kit potentially cure back-puffing problems?
This is exactly the situation. I have no problems starting and maintaining the fire with the damper open; in fact with it open, the stove top temperature gets very hot fast, and I have to close the air control almost all the way to prevent it from over firing. Yet, when I close the damper to engage the cat, it seems to work Ok for a while, but am soon in the same situation with back-puffing, even with the air control open wide open. With the air control closed down somewhat, it starts back-puffing badly. This happened again tonight. The stove top temperature drops, and the cat chamber temperature rises rapidly to 2200 degrees. It is worse if I close the air control as this will produce more smoldering/smoke which will increase the cat temperature even more and cause back-puffing.grommal said:Not all back-puffing issues can be traced to poor draft. We used to have terrible back-puffing with our old stove, yet when you opened the bypass around the cat, it would run away instantly because of the strength of the draft that was already present. Plus, with our new stove, there seems to be zero tendency to puff, and enough draft to start the stove from cold with all the doors closed. Nothing on the chimney was changed. Only the stove.
Opening the air control does help reduce back-puffing, but does not cure it. Not sure what you mean about opening the door as a cure for back-puffing.madison said:grid,
Does opening the primary air prior to opening the stove door change the amount of back puffing? And does the outdoor temperature make any difference with your problem?
Thanks; the chimney sweep is coming Monday to check things out. The funny thing is that he seems to almost not want to deal with it and give my money back. We'll see. As I mentioned in another post, I do wonder if it could be a problem with one of the thermostats. The air control is quite sticky and scratchy when moved, and that is connected directly to the main thermostat. I also wonder if having a 6" flue instead of an 8" is part of the problem. VC mentions a 6" can be used but does not recommend using it this way in fireplace mode (doors open with screen).ddown said:Gridlock said:Could installing an outside-air kit potentially cure back-puffing problems?
I've been following you backpuffing/New stove saga. I'd wait until sweep/shop checks out your setup. I traded a couple stoves before I figured out part of problem was a bad section of class A not sealing and wood quality could have saved about 5 grand and had the Stove I originally bought. Your assuming it's the stove have it checked first. My dealer missed it first three trips until I got pictures during a burn.
Gridlock said:I also wonder if having a 6" flue instead of an 8" is part of the problem. VC mentions a 6" can be used but does not recommend using it this way in fireplace mode (doors open with screen).
Gridlock said:Opening the air control does help reduce back-puffing, but does not cure it. Not sure what you mean about opening the door as a cure for back-puffing.madison said:grid,
Does opening the primary air prior to opening the stove door change the amount of back puffing? And does the outdoor temperature make any difference with your problem?
The issue does seem worse with outside temperatures that are not as cold.
BeGreen said:Yes, backpuffing is a mini-explosion of unburnt wood gas that is often strong enough to force smoke out of pipe seams, past door and top lid gaskets. A big backpuff is something you won't forget. I had a big one while learning about the Castine. It was my fault. I was impatient and had a balky starting fire on which I put too large splits before the kindling bed has a good chance to get going. The fire snuffed out after a few minutes and filled with smoke. Stupid me cracked open the ash pan door to get it quickly started. The moment a flame caught, it ignited the unburnt wood gasses with a mighty whumpf!
It's moments like these when you are very glad the flue has 3 screws per joint and that the stove is well made. I actually looked outside to be sure the cap stayed on. Needless to say I never did that again and stopped ever trying to start the fire using the ash pan door.
Jags said:BeGreen said:Yes, backpuffing is a mini-explosion of unburnt wood gas that is often strong enough to force smoke out of pipe seams, past door and top lid gaskets. A big backpuff is something you won't forget. I had a big one while learning about the Castine. It was my fault. I was impatient and had a balky starting fire on which I put too large splits before the kindling bed has a good chance to get going. The fire snuffed out after a few minutes and filled with smoke. Stupid me cracked open the ash pan door to get it quickly started. The moment a flame caught, it ignited the unburnt wood gasses with a mighty whumpf!
It's moments like these when you are very glad the flue has 3 screws per joint and that the stove is well made. I actually looked outside to be sure the cap stayed on. Needless to say I never did that again and stopped ever trying to start the fire using the ash pan door.
+ 1000 :sick:
You won't forget that sound.
fbelec said:Jags said:BeGreen said:Yes, backpuffing is a mini-explosion of unburnt wood gas that is often strong enough to force smoke out of pipe seams, past door and top lid gaskets. A big backpuff is something you won't forget. I had a big one while learning about the Castine. It was my fault. I was impatient and had a balky starting fire on which I put too large splits before the kindling bed has a good chance to get going. The fire snuffed out after a few minutes and filled with smoke. Stupid me cracked open the ash pan door to get it quickly started. The moment a flame caught, it ignited the unburnt wood gasses with a mighty whumpf!
It's moments like these when you are very glad the flue has 3 screws per joint and that the stove is well made. I actually looked outside to be sure the cap stayed on. Needless to say I never did that again and stopped ever trying to start the fire using the ash pan door.
+ 1000 :sick:
You won't forget that sound.
or sight
My chimney is somewhere between 23 and 26 feet (I measured it the other day but don't remember exactly). The chimney is stone on the outside, about 2/3 of which is inside the house, and the other 3rd juts outside past the exterior wall. The stove sits just outside the fireplace, so the stove pipe runs horizontally for 1 or 2 feet into a T fitting, then runs straight up the chimney. The pipe is 6".fbelec said:how many feet is your chimney? sorry. how tall is your chimney?
how long are you waiting to engage the cat?
what temp is the stove top when you engage?
if your cat is burning that hot you might want to engage a little sooner when the temp is lower and let the stove do it's thing a little slower. it's worth a try.
Good thought. I inspected and cleaned the CAT 3 times already within the past couple of months thinking that that may be the problem, but it didn't make a difference. The last time I cleaned it (on the advice of someone at Woodstock Stoves who was very helpful even though I don't have a Woodstock stove) I used a can of compressed air to flush any ash that might have plugged some of the honeycomb. I also used my vaccuum. The CAT appeared very clean, and it does light up (actually too well, as I've seen CAT chamber temps up to 2,200 degrees (although I believe the Condar guage is reading too high)!Jags said:Plugged CAT? (just thinking out loud).
I looks like it is puffing upward.Jags said:Just revisiting a few things to stir up thoughts.
Back puffing happens because of un-burnt volatiles in the stove or pipe being in a state of non-combustion then having oxygen and ignition re-introduced.
The stove appears to draft well with the cat by-passed. Check!
The fuel appears to be seasoned and ignites well. Check!
You get periods of "proper" burn when cat is engaged, but then will die back to a state where back puffing occurs.
Hey - when this back puffing happens - can you visually see the direction it goes. Does it puff UP or do you see a rush of air coming DOWN?
We use essential cookies to make this site work, and optional cookies to enhance your experience.