Old Mill stove backdrafting

[beenthere]

a cat can be dumb enough to climb a tree and not be able to get back down

Never have seen a skeleton of/or a dead cat in a tree, so they must get back down.  ;)

[martyinmi]

a cat can be dumb enough to climb a tree and not be able to get back down

Never have seen a skeleton of/or a dead cat in a tree, so they must get back down.  ;)

:D :D That's funny--and true all at the same time!

[tyb525]

After rereading this thing a couple times and debating weather or not a stack damper is need I hit on something .

If you are choking down the fire with the intake air what you are doing is shutting off a source of oxygen to the fire .As it smoulders away it's gassing the products of combustion but due to lowered internal temps plus a lack of combustion air the conditions are not such to ignite the gasses .You open the door and it back fires and singes the hair off your arm .

Now it only makes sense that if you more completley burned off the gasses that one you'd get more heat where you need it ,in the stove not going up the stack .Two and also important the more gas you burn off the less rises in the flue and therefore less creosoting when the gasses condense on the sides of the flue .

With a stack damper you can still regulate the temps to keep the flue upwards of 300 degrees which seems to be the magic temp to nullify creosote accumulation .

Take a look at the ashes .They should be nothing but powder if it's set upright .Not lumpy unburned charcoal .

Al, we have a stack damper that restricts draft. If we restrict draft, it slows down and cools forming creosote
more than a good hot draft. Our heat comes from the body of the stove with  fan blowing through it, not from the stack. It is plenty hot that way,and flue temps are right around 400 most of the time.

The fire burns great and gets plenty of air, even with the air vents closed down, while still getting a good draft. With the stack damper closed, it gets smokey and smolders, and flue temps drop. We don't get any woofing.

To the OP, we had draft problems recently, turned out there was a spot right above the tee where the flue enters
the chimney, that the chimney brush didn't reach. After clearing that, all was fine again.

[tyb525]

Now what I said is true for our stove, an '80s Federal Airtight with about 25' of chimney, but it might not work for other setups  ;)

[Al_Smith]

I've read on the net of what a few stove installers suggest about stack dampers  but I'm not so sure everybody agrees with that theory .I don't for one but I also do not have a so called modern stove they are refering to and doubt I ever will have .It is air tight though and 5/16" plate steel --with a damper . ;)

If you stop and think about it the heating stove has been around about as long as there has been the good old US of A in some form or another . The air tight type of course in terms of history are a relatively new innovation .However in the least common denominater they all burn wood and they all produce heat so in theory they all work the same .

A good old barrel stove will put out as much heat as a 2000 dollar high tech catalytic wonder you need a degree in thermal dynamics  to operate .

[johnjbc]

I had the same problem with a stove my dad built years ago. When we lived in our last house I put it in the basement so I had about 20' of chimney. More than It was ever hooked up to before. It has a star wheel on the front door to adjust the intake air. When it got going real hot the star wheel acted like an air nozzle and air entered faster than it could burn. When it spread out it burnt all at once and caused a puff, this made the chimney draw higher. After the puff it pulled a little more air and did it a little worse. It built up to where it was puffing flames back out the star wheel. The fix was to put a longer bolt on the star wheel, and make a 2" circle of metal to mount it on the inside of the door about an inch. This broke up the air jet and prevented the oscillation.
Problem solved 
It was built about 1970 and is currently in my buddies green house



 




 

[Al_Smith]

That thing is about like a heavy duty barrel stove .Looks like an old water pressure tank with a door welded on it .

People might laugh at the old barrel stoves but they have a lot of surface area  and they kept the  army from freezing to death when they built the AlCan highway in WW2 .

[johnjbc]

A couple shovels of soft coal and it kept the whole house warm all night. And if you didn't shut the draft down you could turn the lights off and see it glowing dull red . You can see the grates in the second picture, had to make new ones every few years out of what ever was in the scrap pile.

[Al_Smith]

Oh geeze if you had it full of coal about the size of a baseball and opened up the air you could have forged horse shoes in the fire .That would not be of much good though unless you had horses . I can't imagine getting a horse to climb stairs down into a basement though but I suppose anything is possible .