Running in Reverse

[bigblulbz]

I have a Fisher Papa Bear from the previous owner that was plumbed with a 7" flue. The stove should have 6" and I know this is not helping keep the flue drafting. Unfortunately, the flue is a through wall that goes outside the house. Until I put the correct size flue on I know I will always have a problem getting the stove to run long periods of time. Why does, when the stove begins to cool off overnight and 1st thing in the morning when I open the door and the coals are low, the stove runs in reverse.

My theory is the inside of the house is warmer than the outside and the stove wants to draft in that direction. Any insight is greatly appreciated. This is becoming very frustrating.

 

[begreen]

Could be there's negative pressure in the room. Is this a basement installation?

http://www.woodheat.org/all-about-chimneys.html

 

[bigblulbz]

Yes. Basement installation. We have a large open staircase that I open the window on before I light the fire. Feed it with some nice kindling is gets going and things are great. Its only after the overnight that I have been getting this problem. I've been reading here on the forums that this time of year with the temps may cause some issues as well.

 

[begreen]

As the weather gets colder the draft may improve. If there are any windows cracked open upstairs, an attic hallway vent or staircase unsealed, exhaust fans running, etc. they may be exacerbating the situation. Read the article for more pointers.

 

[bholler]

we usually run 7" on most fishers we have found they generally run very well on 7"

 

[bigblulbz]

I think the fact with the 7" flue & it being exhausted up the side of the exterior side of the house makes matters worse. What do you think?

 

[bholler]

I think the fact with the 7" flue & it being exhausted up the side of the exterior side of the house makes matters worse. What do you think?

Is it insulated class a?

 

[bigblulbz]

Is it insulated class a?

Yes.

 

[begreen]

Most likely it is the basement location together with milder temps.

 

[coaly]

Is this possibly a side or rear vented stove? (not exhausted through the top)

 

[Corey]

If the house is warm and you open a window 'above' where the stove is (ie -up a staircase as you mention) The warm air from the house will generally be escaping through the window which means cold air will try to flow in the house to replace it. The easiest pathway to get the cold air in would likely be coming down your flue, hence the back draft. First step would be not to open windows above the stove. Second, if you have a door to that stairway, you might actually try closing it (at least while opening the stove). That way, heat can not rise out of the basement and pull cool air in through the stove pipe. Alternately a fan placed in / near the stairs so it can 'stuff' the basement full of air may help keep the draft going in the right direction...again, may only be needed while the stove door is open.

 

[coaly]

If the house is warm and you open a window 'above' where the stove is (ie -up a staircase as you mention) The warm air from the house will generally be escaping through the window which means cold air will try to flow in the house to replace it. The easiest pathway to get the cold air in would likely be coming down your flue, hence the back draft. First step would be not to open windows above the stove. Second, if you have a door to that stairway, you might actually try closing it (at least while opening the stove). That way, heat can not rise out of the basement and pull cool air in through the stove pipe. Alternately a fan placed in / near the stairs so it can 'stuff' the basement full of air may help keep the draft going in the right direction...again, may only be needed while the stove door is open.

There you go, keyword "large open stairway" otherwise known as stack effect when the air rises away from stove allowing atmospheric pressure to push the cooler heavy air down chimney. 6 inch is better giving less square inch area for atmospheric pressure to use as well.
If this is a rear vented stove, the situation is worse since the outlet isn't much higher than door opening. (heated exhaust rises easier directly straight up a top vent) Rear vented stove requires double wall pipe on horizontal run to increase heat in chimney. Make sure any horizontal run is tilted up good to gain as much draft as you can.
One of the rare instances a electric draft inducer (stack heater) would start the draft for you when needed.

 

[bigblulbz]

Great. I have the staircase effect as well. I've never batted a thousand before. I am about to purchase a new flue. Any recommended vendors? How are the vendors advertised here?

 

[bholler]

Great. I have the staircase effect as well. I've never batted a thousand before. I am about to purchase a new flue. Any recommended vendors? How are the vendors advertised here?

I would try other solutions before buying a new chimney.

 

[bigblulbz]

I think the previous owner over fired this one too many times.

 

[bholler]

I think the previous owner over fired this one too many times.

Have you had a pro out to evaluate your system yet?

 

[bigblulbz]

Have you had a pro out to evaluate your system yet?

Only when we originally bought the house 3 years ago. He mentioned the same. If you put a flash light in it you will see distorted sections of pipe.

 

[begreen]

Putting in a new insulated 6" flue is certainly not going to hurt and may help a bit. If problems persist then look into addressing the root causes of negative pressure and maybe introduce a fresh air supply close to the stove intake.

 

[bigblulbz]

Putting in a new insulated 6" flue is certainly not going to hurt and may help a bit. If problems persist then look into addressing the root causes of negative pressure and maybe introduce a fresh air supply close to the stove intake.

That is a tough one. The basement is finished with ends of the house not back filled. The end where the flue is exhausted is the driveway. The original owners knocked out the old basement window and threw up a piece of sheet metal and that is how the penetration was handled. The nearest fresh air supply would be to open the door off the garage.

 

[bholler]

That is a tough one. The basement is finished with ends of the house not back filled. The end where the flue is exhausted is the driveway. The original owners knocked out the old basement window and threw up a piece of sheet metal and that is how the penetration was handled. The nearest fresh air supply would be to open the door off the garage.

Why not pull fresh air from next to the chimney?

 

[jatoxico]

If you're going through the trouble of replacing the chimney can you shift gears and take the stove out of the basement? I suffer from the stack effect to some degree so I've had to read up. In some cases it can be a major issue that's not easy to solve. Excepting unusual circumstance, getting it out of the basement ends the problem.

 

[coaly]

I would try other solutions before buying a new chimney.

Yeah, show your wife this $350 draft inducer and she'll start getting up at 3 AM to keep it hot.



(broken link removed to http://www.hvacsolutionsdirect.com/products/Dampers-Draft-Control/Wood-Stove-Vent-Air-Draft-Inducers/DRAW-COLLAR-Wood-Stove-Chimney-Draft-Inducer-SKU1836.html)

It's a 500 watt heater you would only need to turn on when you need it.

 

[bigblulbz]

Why not pull fresh air from next to the chimney?

How though? I don't want to core through the concrete foundation.

 

[bigblulbz]

If you're going through the trouble of replacing the chimney can you shift gears and take the stove out of the basement? I suffer from the stack effect to some degree so I've had to read up. In some cases it can be a major issue that's not easy to solve. Excepting unusual circumstance, getting it out of the basement ends the problem.

The main floor of the house has the pellet stove that is more than adequate for that floor. Not sure what to do. We're going up a floor and there will be another pellet stove there as well.

 

[bholler]

How though? I don't want to core through the concrete foundation.

isnt there space through the old window?