chimney problems

[gsganzer]

I know someone that had a similar problem. The cause was that the flue diameter was too big.

Here's the technical description of what was happening:
The flue gas exits the stove/wood furnace through a 6" pipe. When it entered the chimney, the chimney flue was oversized. This results in a slower velocity through the chimney. The slow velocity results in the flue gas giving up temperature too fast and reaching the dew point, resulting in moisture. In fact the degree of the problem will usually get better or worse according to the outside barometric pressure (changes the dew point) and the firing rate of the stove or wood furnace (lower firing rate results in lower velocity and temp.)

The problem was fixed by lining the flue with a smaller diameter pipe.

 

[Chuck52]

I have an unsued fireplace in my basement and have thought about putting a woodstove down there as there is no other heat except loss from the furnace. However, what's slowed me down is that I've been told I would have to use a metal insert all the way up the chimney in order for it to both draw well and be safe. The expense hurt my penny-pinching soul.

Chuck

 

[powerstroke2000]

I have heard the same thing about the flue being to big I got a 7x7 flue which I wastold was the smallest side.
One think that does sound good was running the stove pipe all the way thru the cross pipe to the flue liners mine just goes just runs in a couple of inches in to a clay thimble as the call it.

 

[djradz]

I'd start by getting rid of the draft breaker, or whatever the technical name is for that swinging device that lets in air. At least try it for a while with it wired shut and sealed over with aluminum foil. It may be that it introduces a lot of cooler air and is serving to help in keeping the chimney cool. Also, don't overload the fire with a lot of wood if you really don't need the heat. If you do, much of the combustion is smoldering rather than a hot fire. With a clay liner in an uninsulated chimney, you are going to have some difficulty, but needing cleaning every two weeks is way to often.

 

[Youare]

Lot of good advice. Sounds like the chimney is not staying warm enough to prevent the condensation of the unburned volatiles in the smoke. If your chimney runs outside the house it takes a long time to warm the whole thing up. If the chimney runs through the house and roof the cold region is usually in the attic space.

Sounds like your chimney is not too large to prevent a decent velocity of the smoke. Having a stainless steel liner will not prevent the condition you are experiencing. I relined an old masonary tile lined chimney last year with a stainless ateel liner because I was concerned about the tile. There were several cracks and missing pieces.

Running a little hotter fire if you can I think would help the situation.

Randy

 

[CTyler]

</font><font color="blue" class="small">( I'd start by getting rid of the draft breaker, or whatever the technical name is for that swinging device that lets in air. At least try it for a while with it wired shut and sealed over with aluminum foil. It may be that it introduces a lot of cooler air and is serving to help in keeping the chimney cool. )</font>

If you shutdown the air flow on the intake your shutting/slowing down the burn process. This will drop the heat output from the stove and lower the stack temp. The more air you let in the hotter it will be, to a point.

 

[Old_Hickory]

I have one of those "barometric dampers" and I do not think it is that great,I am like you I think it keeps my chimney too cool. I get a lot of creosote in my chimney too.

 

[powerstroke2000]

The damper I have is a manual damper that is in the pipe itself it doesn't let air in it just restricts the flow but I can't get it hot enough to use it. The idea of it I believe is to open the stove up more to produce more heat then close the damper slightly to keep temps of the pipe from overheating.

Anyhow I have been burniong hotter and seems to be helping

 

[Old_Hickory]

Do you have a good angle/slope/rise from the wood stove to the chimney?In other words what I am asking is does the flu from the stove to the chimney have a good rise ?

 

[CTyler]

Your talking about the chiminey height past the roof line right?
So if it sticks up 2' then you draw a straight/level line to the up side of the roof and it should be 10' min distance. If the distance is shorter than that you need to raise the stack. That just happens to be the minimum requirement for my wood stove with a 6" flue. Yours is probably different.