WOW.. Talk about getting your attention..

[84Buckeye]

This is my first year burning. Everythings been going well to this point but all that changed today.
I was scooping out some coals on my wood furnace earlier today to make room for some wood.
Seemed to be more smoke than usual despite my best efforts to minimize smoke (open the damper
all the way and very, very slowly open the door) about a half hour later the smell of smoke was
terrible.. So I ran downstairs and looked through the glass and saw no flame, then seconds later a
HUGE flame and smoke bellowing out everywhere.. kept repeating.. no flame.. then huge flame and
smoke..

Brain going a thousand miles and hour!!

So i completely closed the damper and let the darn thing burn down for a few minutes.. seemed
more like hours though.. So despite the smoke which was pouring out like crazy now.. I figured this was
the best course of action. Eventually it cooled down enough and I emptied it out. The wood was
black!! Very HOT and black as coal.

I've been cleaning my heat exchangers and outlet tube every couple weeks and the cresote
build up did not look that bad.. so I wasn't overally considered about what the stainless steel
liner looked like.

Looking back.. I think I dodged a very BAD situation!

 

[patch53]

So, what was the problem? Sounds like something partially plugged or a restriction of some kind.

 

[84Buckeye]

I have no idea patch. There's an air inlet on the bottom of the door that I try my best to keep coals away from.
The coals glow in-line with it in the bed.. There's also a air inlet in the middle of the damper.. But its path is hidden so I dont
have any idea on how to determine if its being restrictive.

 

[patch53]

Have you checked your chimney or flue? I wouldn't light another fire in there until you find out what the problem is.

Pat

 

[Fsappo]

It could be a blow back from adding very dry wood to a hot bed of coals. The gases are released from the wood but dont burn fast enough to cause "normal" combustion. Lots of wood burners can create puffing. I remember old catalytic VC stoves doing it, as well as the old wood guns by eshland. Of course, this can be enhanced buy a clog in the smoke path. Normally cracking the door open so the wood actually starts to burn will help stop this problem. Keep near the boiler when this is happening and only do it for a short time.

 

[laynes69]

You may have some buildup in the flue. Are you burning the unit hot before allowing the damper to close and is your wood good and seasoned?

 

[Jroz]

I would go for the Flue first, Is your neighbor missing a cat?

 

[84Buckeye]

Thanks for the help guys.. I took out some coals and added about 6 pieces of slab (never been a problem before) but the slab
wasn't burning so I rearranged them on end. About 15 minutes later is when I noticed the smell of smoke upstairs. There wasn't a
lot of coals, so minus the slab it didn't take much effort to totally unload the bed.

Laynes.. I have not been sliding the upper combustion sheet forward when cleaning the left and right heat exchangers. Not
sure if that would be a concern or not. The wood is pretty dry.. But I have been going through a tremendous amout of wood
this year. Part of this stems from the fact that my older home has no insulation to speak of yet to this point, attic or wall. That
is the next project. As you know.. the damper is controlled by the thermostat and since it hardly ever got up to even a decent
temp (70) the damper is always open some.

I shut the unit down for the year.. The outlet tube when you look back at the stove pipe looks dirty.. really dirty! Is it common
to remove the stove pipe and clean it out a couple times a year? I'm going to clean the flue and get everything ready for next
year.. I already have enough wood for next year.. I guess I expected a little to much from the unit with a home with no insulation!

 

[karri0n]

Thanks for the help guys.. I took out some coals and added about 6 pieces of slab (never been a problem before) but the slab
wasn't burning so I rearranged them on end. About 15 minutes later is when I noticed the smell of smoke upstairs. There wasn't a
lot of coals, so minus the slab it didn't take much effort to totally unload the bed.

Laynes.. I have not been sliding the upper combustion sheet forward when cleaning the left and right heat exchangers. Not
sure if that would be a concern or not. The wood is pretty dry.. But I have been going through a tremendous amout of wood
this year. Part of this stems from the fact that my older home has no insulation to speak of yet to this point, attic or wall. That
is the next project. As you know.. the damper is controlled by the thermostat and since it hardly ever got up to even a decent
temp (70) the damper is always open some.

I shut the unit down for the year.. The outlet tube when you look back at the stove pipe looks dirty.. really dirty! Is it common
to remove the stove pipe and clean it out a couple times a year? I'm going to clean the flue and get everything ready for next
year.. I already have enough wood for next year.. I guess I expected a little to much from the unit with a home with no insulation!

I don't think "Overuse" would cause something like this, unless it's not actually burning most of that time and is smoking and forming creo deposits... Does your boiler idle a lot? Do you have thermal storage?

Also, was anything calling for heat when you experienced this, or was it idling?


edit: Ok, I'm not sure if this is a gasifier or a traditional furnace/boiler. Also, has your wood been split and dried for a year?

 

[Hunderliggur]

I had a problem like this. It turned out that the screen on my chimney cap was clogged. A combination of ash, creasote, and damp weather combined to clog the mesh. Removed the cap and it tapped out easily. Hasn't happened again. Check your chimney cap and/or flue. Better to fix now than forget next fall.

 

[laynes69]

Having no insulation you will burn alot of wood. You do need to pull the baffle forward if you are pushing everything to the rear of the furnace like the instructions. I don't and I pull everything forward to the front and empty it there. If your wood isn't seasoned properly then you won't get the heat and the furnace won't operate properly. Plus it will cause excessive creasote buildup. Once you get insulation in the house and good dry wood you shouldn't have to worry about creasote. We have nothing in the chimney and a little buildup in the flue. I checked it mid season and it was fine. Do you have a barometric damper on the furnace and what kind of chimney do you have? How many cords have you burnt this year?

 

[horrocksd]

This may not apply, but is it possible that your boiler is somehow allowing the damper to shut when there's a heavy draw on the chimney such as during a strong wind, or a very strong fire? My 30 year old Vermont Castings wood stove does this occassionally and it's scary. The draft control on the stove is on a coil spring with a chain going down to a flapper valve. If I overfire the stove it noticeably can't keep up with evacuating all the gases produced. It will draw real hard, overcome the spring tension on the damper control and suck the damper shut. Then gases build up, eventually ignite and create a sizeable blow-back. Then it cycles and keeps doing it every 40-60 seconds. Just for a nice touch the smoke alarm in the house goes off adding to the tension and confusion!

The way I found to eliminate the sucking and puffing cycle is to insert a piece of coat hanger just behind the flapper valve damper so that it keeps the damper from sucking shut, but still allows a little air in. The narrowly opened damper slows the burn down, but keeps it burning enough to stop the sucking and puffing cycle. It only takes 3-4 minutes to stop. Again, is it possible your damper is somehow being drawn shut when you have a large active fire or heavy winds, or both?

 

[horrocksd]

Here's an interesting post from another website I ran into that talks about "puffing" caused by burning over-dry wood. Hope this helps.

Jim K in PA said...
Tom - thanks for the info on the Wilo. I think I am going to use a delta P based VS pump for my house zones, so I will look into the Wilos.

I have been burning wood that is almost TOO dry. I want to get a moisture meter to find out what the content is, but it will probably be all gone before I do. I had a problem with the ultra-dry wood burning too fast, causing the GARN to "puff", or essentially be gasping for more air. This is with a 3/4hp Dayton jet pump fan motor pulling in hundreds of CFM!!

I am also burning several cords of scrap wood left from the farmhouse renovation and new addition construction. I love being able to heat the house with what would have otherwise been landfill or burn barrel fodder. I mix it in with the cord wood.

February 12, 2009 1:35 PM

 

[southbound]

I had a problem like this. It turned out that the screen on my chimney cap was clogged. A combination of ash, creasote, and damp weather combined to clog the mesh. Removed the cap and it tapped out easily. Hasn't happened again. Check your chimney cap and/or flue. Better to fix now than forget next fall.

Me too..

Got ride of the screen and never looked back...........