Very Poor Chimney Draw

[antlerman]

My friend has a stove that he had installed - all in he spent almost $6k. The stove is a Hearthstone (see pic - the same brand I own but have not yet used). He said that it is a nightmare to get a fire going. He has so much back-draft when trying to light a fire that it actually blows out the matches AND a lighter! He has resorted to using a hairdryer for 10 minutes or so to warm the chimney from inside the stove before he can even get a lighter or match to burn long enough to catch the paper on fire. Otherwise, if he doesn't do this, even if he's lucky enough to get it burning, it will fill the basement with smoke and will not draft.

I think the chimney needs another 2-3 feet on top? It appears to be the "10 ft from nearest peak" but not high enough above the peak of the roof. Your thoughts please....

 

[begreen]

This sounds like strong negative pressure in the basement. What was the outdoor temp at the time of testing? Have your friend on a cool day try opening a nearby window in the basement about an inch and see if the back draft issue is reduced. If that works then investigate to see if there are house issues that are exacerbating the problem. Things to look for would be a leaky attic door, or ceiling entry or ceiling vent. Open windows upstairs, exhaust fan running (bath, kitchen, dryer), can also cause issues with basement installs.

 

[jetsam]

All the elbows are not helping.

Could be as begreen said.

Also, I see on the weather report that it will be 80 in Manchester, MI tomorrow. Nobody's flue drafts well unless it is colder outside than inside. If it's 80 out and 60 in the basement, it *should* be drafting backwards.

 

[antlerman]

The fires he made were last year, and it was so difficult he all but gave up on using the stove. He said he always opened a window, after the first time, because there would be smoke in the room every time he tried to start a fire - at least until he came up with the hair dryer blowing up the chimney technique.

Do you think the exterior chimney is high enough?

Thanks.

 

[brenndatomu]

Looks to me like he has 18-20' total chimney height, that should draft pretty well. It may not quite be high enough above the roof, and the surrounding trees may be screwing with things too.
But all in all, I agree with @begreen , I bet it is something with the way the house "breathes"...

 

[vwmike]

Install looks pretty good actually, the angle thimble should help a lot compared to the traditional 90s and a T.

I also fought a similar problem on my own house. The stove definetly needs an outside air kit. Also make sure the other appliances in the basement have their own air supply. Upstairs make sure everything is air tight like pot lights, attic hatches, make sure bath fans and hood fans are ducted out side and not just into the attic.

 

[Ludlow]

Gotta have some kind of air intake to the house at level with or below the stove at least until a draft is established. Open a door in the basement until the stove warms up and the draft is established. Think about it. The stove will need to pull air down to the stove to send it up. That is a lot to ask of a cold flue.

 

[antlerman]

Ok, good points and ideas.

What is "an outside air kit?"

 

[brenndatomu]

You run an air supply line from the outside directly to the stove...many stoves have a way to hook up to them. Outside air kit, or OAK

 

[jetsam]

If a house is very tight, the stove can't pull air from outside like it could in an older/leakier house. The pressure inside the house drops, and the draft gets weaker and weaker as the pressure goes down. Giving the stove its own air supply solves the problem.

Even people with old houses can benefit, because the 0 degree combustion air is being drawn in at the stove instead of through that leaky window in the back bedroom...

The first step is to check with the stove manufacturer's tech guys- an OAK may not be allowed at all due to the basement install (risk of draft reversal).

 

[Ludlow]

I believe the risk of an OAK in a basement comes from people routing the intake above the stove and foundation. You want the OAK to remain level or below the stove in it's entirety.

 

[mcstatz5829]

I believe the risk of an OAK in a basement comes from people routing the intake above the stove and foundation. You want the OAK to remain level or below the stove in it's entirety.

This confuses me. Does that mean it’s pulling air through the soil?

 

[yooper08]

This confuses me. Does that mean it’s pulling air through the soil?

No, if the stove is in the basement and the entire basement is below grade, what tends to happen with OAKs is that the kit is installed like a dryer vent...attached to stove and installed in opening near ground level. This can be a no-no as the OAK can now act like another flue in the right conditions. Walkout basements make it much easier/better to install OAKs since the run can stay level or below the stove.

 

[Ludlow]

This confuses me. Does that mean it’s pulling air through the soil?

Is your basement backfilled on all sides?

 

[yooper08]

Things to look for would be a leaky attic door, or ceiling entry or ceiling vent.

@antlerman, these should be checked. In our house, we have AC ducts in the attic which pour down cold air if left unsealed over winter. This just means warm air is going up, which exacerbates stack effect and creates the negative pressure in the basement. So, as stupid an idea as it was to cut a bunch of holes that open the house to the attic, I have to seal off those vents each fall (and I hate it). Same goes for whole-house fan, which eventually I just need to get rid of the ugly thing.

 

[Ludlow]

Same goes for whole-house fan, which eventually I just need to get rid of the ugly thing.

I put that window insulator plastic over mine every October. If I dont it will rain in the hallway under certain conditions.

 

[mcstatz5829]

Is your basement backfilled on all sides?

Yes but I don’t have a stove in my basement - curious how you get a OAK below the stove when it is backfilled on all sides.

 

[yooper08]

I put that window insulator plastic over mine every October. If I dont it will rain in the hallway under certain conditions.

That's what I use for the AC vents. The whole house fan I have some sort of insulation roll the previous owners had but never used. It's white and goes on with Velcro strips. Haven't taken it down since last winter.

 

[yooper08]

Yes but I don’t have a stove in my basement - curious how you get a OAK below the stove when it is backfilled on all sides.

You put the stove above grade.

If the stove needs an OAK because of the house, a basement fully below grade basically rules out that location in my mind.

 

[bholler]

Yes but I don’t have a stove in my basement - curious how you get a OAK below the stove when it is backfilled on all sides.

You can run fresh air near the stove but you cant hook it up directly

 

[begreen]

You can run fresh air near the stove but you cant hook it up directly

The OAK on some stoves indirectly connects this way, perhaps to cover this situation.

 

[bholler]

The OAK on some stoves indirectly connects this way, perhaps to cover this situation.

Technically no you still cant hook it up. But practially if it is not sealed i doubt it would cause a problem.

 

[yooper08]

You can run fresh air near the stove but you cant hook it up directly

True, definitely an option, had my blinders on OAKs. Could run a vent to the floor (prevent lots of warm air going outside) in the same room as the stove.

 

[Ludlow]

If you have to resort to dumping ice air into the room to make it work I would scrap that location and put it upstairs.

 

[mcstatz5829]

You can run fresh air near the stove but you cant hook it up directly

That makes sense. From what I’ve read about pressure gradients within warm houses, the basement is almost always going to be negative pressure, and you’re basically guaranteed a backdraft until the flue is hot, unless you have an OAK or find a way to equalize the pressure with another source of fresh air.

Is that right?