Downdraft! Help please!

[Speace0181]

I've been reading allot about downdrafts and negative pressure. I have a super 27 that I brought from my old house. It was used on the main floor and never had any trouble with it.
Our new home has an exterior masonry chimney with clay liner going to the basement. The house is a two story with the chimney on the east side of the home which goes 4-5 feet above the peak of the roof. Since hooking it up I have noticed I have to run the air intake about half open to get any heat out of it. I also have noticed there is a substantial downdrafts when not in use. I have to leave the basement door cracked to get the fire going and if I close it anytime prior to a decent fire it'll smoke back through the dvl pipe.The furnace is about ten feet to the right of it and is a geothermal unit.
I contacted the company i purchased muy stove from and they thought an outside combustion hose would need to be used to solve it. I agree it might solve the combustion part but would it benefit me from having the smoky smell in the basement? I guess I'm asking if it would solve the downdraft when not in use?
Any help would be appreciated. I'd really like to use the stove as supplemental but that smell is being circulated through the whole house.

 

[begreen]

Negative pressure in the basement is not uncommon, especially if the upper part of the house is poorly sealed. If there is an attic vent or stairwell close that up. Any air leakage upstairs will make the situation worse. Or move the stove upstairs and be done with problem.

 

[Speace0181]

That could very well be the issue. Has anyone figured out a good way to find leaks in the attic yet? I think I may try the incense sticks to see, but I heard I may get mixed results.

 

[yooper08]

I would just find all of the penetrations into the attic and seal them up, even if temporarily for the season.

 

[Doc C]

That could very well be the issue. Has anyone figured out a good way to find leaks in the attic yet? I think I may try the incense sticks to see, but I heard I may get mixed results.

I use the smoke in a bottle for hunting. Not the cheap primos stuff that is like baby powder and comes out with half smoke and half powder that gets all over everything.

It's the stuff that makes good smoke and just hangs in the air. Then I go close to the penetrations and test the area with it.

 

[Marshy]

Google smoke pen.

 

[Speace0181]

I'll look into the smoke pen. I spoke with a couple of dealers today. The one I purchased the stove from suggested that the 90 degree elbow I have installed plus the 28"horizontal run may be the culprit. I pulled the pipe out of the thimble today and lit a match. It went mostly up the flue and then back a little. However the temps are inthe 50s today so I'll have to wait until it cools down again. I also realized there is no cap on the chimney either. So, i am hoping with two 45s and a chimney cap it might resolve the issue. What do you all think?

 

[begreen]

Sounds like a good plan. It would be worth a try to soften that 90º turn by using a pair of 45's and an offset. That will eliminate the 28" horizontal. Do this with double-wall stove pipe to keep the flue gases hotter. Something like this.

 

[yooper08]

No cap? Would that also mean there’s no liner in the chimney?

 

[Speace0181]

Correct. No liner in the chimney. It is 6.5 x 6.5 inner diameter clay liner in a masonry chimney. So I assume it's 8x8 o.d.

 

[Speace0181]

 

[Speace0181]

Still waiting to go get pipe this weekend. However, i did a little test while the dryer was running and the flue pipe disconnected last night. When the dryer is running it pulls a downdraft. When off, smoke goes up chimney. I am hoping with the two 45s and the stove hooked up with the damper closed i won't get any downdraft. What is your opinion? I did check it with the furnace on and that is not the culprit. I assume that since it doesn't exhaust to the outside it is not causing a vacuum. If it is just the dryer causing the issue that is manageable, and i would imagine when a fire is lit shouldn't be an issue.

 

[begreen]

The draft is marginal the dryer running, maybe a bathroom or kitchen fan will also cause downdraft when conditions are right. Even a window inadvertently open on the 2nd floor could cause it. The problem is that one doesn't know when this will happen. Murphy's Law says this may happen at the worst time.

 

[missedbass]

I keep a window cracked in the basement other wise I have backdrafts occur. Be careful if you use the stove 24/7 and not your primary heat you could get a backdraft on your boiler flue.

 

[Speace0181]

Alright now I'm scratching my head. I checked the flue today after sealing up my attic entrance. Had the door going from 1st floor to basement open stuck smoke stick in front of the flue and it went up like it's supposed to! So I turned the dryer on and it still works great. Go and shut the upstairs door and downdraft occurs again. So I'm thinking okay I can handle leaving the upstairs door open. Well, long story short. Tonight I tried to replicate the test. The upstairs door made 0 difference. Either way I had a downdraft. The outside temp was about the same. Only difference was the sun. Possibly warming the masonry chimney? I don't know guys. I'm about ready to sell my stove. What's your opinions on an OAK? I'm hearing mixed reviews.

 

[Doc C]

Alright now I'm scratching my head. I checked the flue today after sealing up my attic entrance. Had the door going from 1st floor to basement open stuck smoke stick in front of the flue and it went up like it's supposed to! So I turned the dryer on and it still works great. Go and shut the upstairs door and downdraft occurs again. So I'm thinking okay I can handle leaving the upstairs door open. Well, long story short. Tonight I tried to replicate the test. The upstairs door made 0 difference. Either way I had a downdraft. The outside temp was about the same. Only difference was the sun. Possibly warming the masonry chimney? I don't know guys. I'm about ready to sell my stove. What's your opinions on an OAK? I'm hearing mixed reviews.

It sounds like your stove is the perfect candidate for outside air. I’m not sure what you are speaking of by hearing mixed reviews other then some stoves don’t need them.

I have a proximity air intake with a damper built in across the room from the wood stove. Also built into my hearth I have a vent that acts as an outside air kit pretty much. Not a direct hook up to the stove but the vent is only a couple inches from my oak hook up.

I don’t really see a down side in trying an outside air kit. As you stated you are about ready to sell your stove anyway. Spend a couple bucks and try it.

 

[Doc C]

And maybe I missed it but your chimney is clean correct? When my chimney started to get clogged due to other issues one year I develop a horrible down draft.

I’m sure you ruled that out though.

 

[Speace0181]

And maybe I missed it but your chimney is clean correct? When my chimney started to get clogged due to other issues one year I develop a horrible down draft.

I’m sure you ruled that out though.

I've only burned twice since cleaning. So I wouldn't think that would be the issue. And had to run the damper on medium due to lack of combustion air from poor draft and competition with dryer etc..

I don't have a problem installing the combustion kit. I am positive it would help the stove draw better when in operation. My question is whether or not it would resolve the downdraft when not in use.

 

[Doc C]

I've only burned twice since cleaning. So I wouldn't think that would be the issue. And had to run the damper on medium due to lack of combustion air from poor draft and competition with dryer etc..

I don't have a problem installing the combustion kit. I am positive it would help the stove draw better when in operation. My question is whether or not it would resolve the downdraft when not in use.

As far as resolving the down draft when not in use I can almost guarantee that it will not .

I can say that from personal experience and also from thinking about the way stoves work.

IF you could seal your stove 100% including the holes in the bottom if it has them, any connections in pipe or stove, the damper, and all other holes and connect an air kit then I guess in theory it could help but I don’t think it’s feasible.

 

[stovelark]

It sounds like you are doing/have done things to try and manage the situation. If you still are getting the downdraft smell coming from the stove's intake bleeding out into the basement- with an outside air kit installed, in theory this negative loop would vent all or mostly back outside, no?? I would try the fresh air kit, not a lot to lose. Negative pressure planes cause a lot of headaches for woodstove owners operating in the lower levels of houses. Just make sure the piping to the stove for air is metal..... good luck with it..

 

[Doc C]

It sounds like you are doing/have done things to try and manage the situation. If you still are getting the downdraft smell coming from the stove's intake bleeding out into the basement- with an outside air kit installed, in theory this negative loop would vent all or mostly back outside, no?? I would try the fresh air kit, not a lot to lose. Negative pressure planes cause a lot of headaches for woodstove owners operating in the lower levels of houses. Just make sure the piping to the stove for air is metal..... good luck with it..

The only thing I found that helped after fighting downdraft when not burning for about 3 years was a lit candle placed in the stove. It worked surprisingly well. My wife and I ended up making about 25 large candles in order to always have some to keep in the stove when not burning.

 

[Speace0181]

I do believe I'll try the air kit, mainly due to the way I have to operate the stove now. I know I have issues with getting enough combustion air because I have to run the damper allot more open than the old house. There it was installed on the ground floor with a stainless chimney. It would run you out and actually probably had too much draft after turning damper all the way down. Had me scared a few times when secondaries would kick in.
I believe part of the smell was from a combo of the damper setting and the downdraft. I noticed when I cleaned the ashes there were some coals that didn't burn completely. I think that is where the smell came from. Maybe.

 

[stovelark]

I will add too, since you are running into a masonry chimney, even a 7 x 7 flue, which size wise meets code, it prob still hinders the stove drafting as well, it stays colder longer and cools quicker. I see you are in Ky, a milder area temp wise, was your other home there too? We all agree that the issue is negative pressure- I do believe in this case, an OAK might positively impact the situation... Good luck with it.

 

[Pertzbro]

Surprised you don't have a liner down the masonry chimney. Not as cheap to do compared to an outside air hookup but would likely help... Other option would be to put one of these on top of the chimney. Helps with the wind.

https://extendaflue.com/

 

[Gyprat]

I'm an industrial engineer and not a stove expert by any means. A lot of this can be explained by simple physics. All chimneys may have some downdraft when stove is not in use. This depends chimney location (and height) in relation to the house structure, outside wind and wind direction, any open windows, HVAC system recirculating air inside the house etc. This is normal. What's not normal is that you have smell caused by downdraft.
Adding an external air supply system will not reduce the downdraft but may relocate the smell to where the air intake will be. The air intake should be very tight, with no gaps to keep the smell from inside the house.
I find it a bit strange that you get smell from a stove when it's not in use. Perhaps it only smells when the stove is done burning and you simply let it cool down for a few days while there are some slow burning coals in the stove. This is probably caused by lack of updraft from the cold chimney. This can be fixed by installing a dual-wall chimney liner inside your existing chimney. This will keep the inner chimney pipe a lot warmer thus creating sufficient draft, even at lower exhaust temperature.
Adding cap on the chimney will help to keep the moisture out and possibly reduce downdraft. A properly shaped chimney cap will actually create additional draft (low pressure) in the chimney when wind blows across it. If the cap is missing, wind may create slightly positive pressure in the chimney thus increasing downdraft (Bernoulli's principle from middle school physics).