# Running in Reverse



## bigblulbz (Oct 4, 2015)

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.


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## begreen (Oct 4, 2015)

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

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


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## bigblulbz (Oct 4, 2015)

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.


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## begreen (Oct 4, 2015)

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.


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## bholler (Oct 4, 2015)

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


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## bigblulbz (Oct 4, 2015)

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?


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## bholler (Oct 4, 2015)

bigblulbz said:


> 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?


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## bigblulbz (Oct 4, 2015)

bholler said:


> Is it insulated class a?


Yes.


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## begreen (Oct 4, 2015)

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


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## coaly (Oct 6, 2015)

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


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## Corey (Oct 6, 2015)

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.


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## coaly (Oct 6, 2015)

Corey said:


> 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.


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## bigblulbz (Oct 8, 2015)

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?


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## bholler (Oct 8, 2015)

bigblulbz said:


> 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.


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## bigblulbz (Oct 8, 2015)

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


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## bholler (Oct 8, 2015)

bigblulbz said:


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


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


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## bigblulbz (Oct 8, 2015)

bholler said:


> 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.


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## begreen (Oct 8, 2015)

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.


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## bigblulbz (Oct 9, 2015)

begreen said:


> 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.


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## bholler (Oct 9, 2015)

bigblulbz said:


> 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?


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## jatoxico (Oct 9, 2015)

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.


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## coaly (Oct 9, 2015)

bholler said:


> 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. 



http://www.hvacsolutionsdirect.com/...Wood-Stove-Chimney-Draft-Inducer-SKU1836.html

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


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## bigblulbz (Oct 9, 2015)

bholler said:


> Why not pull fresh air from next to the chimney?


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


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## bigblulbz (Oct 9, 2015)

jatoxico said:


> 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.


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## bholler (Oct 9, 2015)

bigblulbz said:


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


isnt there space through the old window?


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## bigblulbz (Oct 10, 2015)

bholler said:


> isnt there space through the old window?


There is but when I install the new flue I was going to have my mason block it up so I can use a thimble and route it through the wall properly. I don't have to block it entirely but what do you suggest? I'll take a few photos of the whole system so everyone can see what I'm working with.


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## coaly (Oct 10, 2015)

When I was in the propane business, a burner requiring fresh air like in your case would be 3 inch PVC through the wall or closed off window as in your case. An elbow outside pointing down with insect screen. An elbow inside pointing up. That way warmer inside air won't drop down the pipe. Warmer outside air in summer may rise into basement, so blocking it for the summer helps prevent humid air entering and condensing inside. It will only draw what it needs during winter. It was called an elephant trunk by some, and customers would feel the cold air rushing in when the burner was on and plug it with rags. They didn't realize the burner and chimney draft will pull from every crack in the house to get air anyway. So I explained it was better to have cold air feed the burner directly from the intake close to it than create drafts through the house from anywhere it can. Sometimes the house intake becomes a unused fireplace that smells all the time that people think is normal... Every exhaust fan including bath, range hood, dryer, central vac needs a source of air. It alleviates a lot of problems.
If you don't like the idea of a cold air intake, a metal box can be made with HVAC duct work. Run the cold air inlet pipe into it along with holes on the sides to become a mixing box for inside and outside air. Stubborn customers didn't seem to have a problem with that. And a couple holes on top of the box they couldn't plug. 

Your stove now gets air that cools and drops down the stairs and moves toward it. The intake helps prevent it from burning your indoor heated air. You want the air to circulate, not go up the chimney.
The best case scenario for stairways is having the stove on the opposite side of the building away from stairs. 2 vents (with auto closing fire dampers) through the floor above stove allows heated air to rise. (sometimes with small duct booster fans as well) As it cools, it must traverse the house to drop back down the stairs to be heated again. If you only have the single stairway rising up, you don't get the circulation through the house with a good return system. The cold air drops like a waterfall down the steps and back toward stove to be reheated. Goldilocks and Honey Bear for factory built homes have an air intake built into the stove for connection to outside making them more efficient Fisher models.


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## bigblulbz (Oct 11, 2015)

coaly said:


> When I was in the propane business, a burner requiring fresh air like in your case would be 3 inch PVC through the wall or closed off window as in your case. An elbow outside pointing down with insect screen. An elbow inside pointing up. That way warmer inside air won't drop down the pipe. Warmer outside air in summer may rise into basement, so blocking it for the summer helps prevent humid air entering and condensing inside. It will only draw what it needs during winter. It was called an elephant trunk by some, and customers would feel the cold air rushing in when the burner was on and plug it with rags. They didn't realize the burner and chimney draft will pull from every crack in the house to get air anyway. So I explained it was better to have cold air feed the burner directly from the intake close to it than create drafts through the house from anywhere it can. Sometimes the house intake becomes a unused fireplace that smells all the time that people think is normal... Every exhaust fan including bath, range hood, dryer, central vac needs a source of air. It alleviates a lot of problems.
> If you don't like the idea of a cold air intake, a metal box can be made with HVAC duct work. Run the cold air inlet pipe into it along with holes on the sides to become a mixing box for inside and outside air. Stubborn customers didn't seem to have a problem with that. And a couple holes on top of the box they couldn't plug.
> 
> Your stove now gets air that cools and drops down the stairs and moves toward it. The intake helps prevent it from burning your indoor heated air. You want the air to circulate, not go up the chimney.
> The best case scenario for stairways is having the stove on the opposite side of the building away from stairs. 2 vents (with auto closing fire dampers) through the floor above stove allows heated air to rise. (sometimes with small duct booster fans as well) As it cools, it must traverse the house to drop back down the stairs to be heated again. If you only have the single stairway rising up, you don't get the circulation through the house with a good return system. The cold air drops like a waterfall down the steps and back toward stove to be reheated. Goldilocks and Honey Bear for factory built homes have an air intake built into the stove for connection to outside making them more efficient Fisher models.


That's a lot to take in. Will review again in the morning.


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## bigblulbz (Oct 18, 2015)

coaly said:


> When I was in the propane business, a burner requiring fresh air like in your case would be 3 inch PVC through the wall or closed off window as in your case. An elbow outside pointing down with insect screen. An elbow inside pointing up. That way warmer inside air won't drop down the pipe. Warmer outside air in summer may rise into basement, so blocking it for the summer helps prevent humid air entering and condensing inside. It will only draw what it needs during winter. It was called an elephant trunk by some, and customers would feel the cold air rushing in when the burner was on and plug it with rags. They didn't realize the burner and chimney draft will pull from every crack in the house to get air anyway. So I explained it was better to have cold air feed the burner directly from the intake close to it than create drafts through the house from anywhere it can. Sometimes the house intake becomes a unused fireplace that smells all the time that people think is normal... Every exhaust fan including bath, range hood, dryer, central vac needs a source of air. It alleviates a lot of problems.
> If you don't like the idea of a cold air intake, a metal box can be made with HVAC duct work. Run the cold air inlet pipe into it along with holes on the sides to become a mixing box for inside and outside air. Stubborn customers didn't seem to have a problem with that. And a couple holes on top of the box they couldn't plug.
> 
> Your stove now gets air that cools and drops down the stairs and moves toward it. The intake helps prevent it from burning your indoor heated air. You want the air to circulate, not go up the chimney.
> The best case scenario for stairways is having the stove on the opposite side of the building away from stairs. 2 vents (with auto closing fire dampers) through the floor above stove allows heated air to rise. (sometimes with small duct booster fans as well) As it cools, it must traverse the house to drop back down the stairs to be heated again. If you only have the single stairway rising up, you don't get the circulation through the house with a good return system. The cold air drops like a waterfall down the steps and back toward stove to be reheated. Goldilocks and Honey Bear for factory built homes have an air intake built into the stove for connection to outside making them more efficient Fisher models.



Finally got some photos.


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## bigblulbz (Oct 18, 2015)

bigblulbz said:


> Finally got some photos.
> 
> View attachment 164396


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