Downdrafts while not burning

[wetwood4life]

Hi all, last fall I had a wood stove and chimney installed in our house. We're new to wood burning. Since then I've noticed reverse drafts when we're not burning. The room will smell bad like stale soot. I can feel the cold air pouring down into the firebox, and if I try starting a fire all the smoke comes into the room until I can fix the draft by lighting newspaper stuffed up the chimney.

Our chimney is 3' double wall, 90deg out the wall, then 16' class A triple-wall straight up. Our house is 100 years old and not airtight so I don't think this is caused by vent fans but it's likely on any overcast or rainy day. Is this a normal part of wood stove ownership? Any tips to prevent the smell during the off season?

 

[Kevin Weis]

That will happen when the the air in the room is colder than outside. What I do is stuff a towel in the pipe to shut the downdraft. Just have to remember to take it out prior to lighting the stove for the season. This happens mostly when the air conditioning is on during the warmer humid months.

 

[stoveliker]

This happens when the air in the pipe is colder than the air in the room. Cold air sinks.

 

[Eman85]

How is the chimney in relation to the roof/ridge of the house? Wind can come over the roof and down the chimney.

 

[begreen]

If the house is quite leaky, that may be the issue. Air leaks on the second floor or at an attic door or ceiling vent can cause the house to act like a chimney, pulling in air from the stove. Sealing up leaky windows, attic ceiling vents, an attic door, etc. can reduce this effect. Kitchen and bath fans and clothes dryer venting can exacerbate the issue.

If the stove is in the basement, then the problem can be worse due to the above mentioned points and also air being used for a furnace or gas hot water heater.

 

[NewGuy132]

Hi all, last fall I had a wood stove and chimney installed in our house. We're new to wood burning. Since then I've noticed reverse drafts when we're not burning. The room will smell bad like stale soot. I can feel the cold air pouring down into the firebox, and if I try starting a fire all the smoke comes into the room until I can fix the draft by lighting newspaper stuffed up the chimney.

Our chimney is 3' double wall, 90deg out the wall, then 16' class A triple-wall straight up. Our house is 100 years old and not airtight so I don't think this is caused by vent fans but it's likely on any overcast or rainy day. Is this a normal part of wood stove ownership? Any tips to prevent the smell during the off season?

There's a bunch of us from Central MA. What town are you from?

 

[mikey]

Where does the draft come out of, is your damper closed tightly, My Jotul 602 v2 does not close completely as to meet the efficiency standard that’s required but I never notice a draft.

 

[begreen]

Where does the draft come out of, is your damper closed tightly, My Jotul 602 v2 does not close completely as to meet the efficiency standard that’s required but I never notice a draft.

Every home is different. The same stove in the OP's situation might exhibit the same issue. As noted, the air never is completely closed off. Often the secondary air is unregulated.

 

[wetwood4life]

Thanks for the great responses!

@Kevin Weis - thanks, stuffing the chimney in the off season seems like it'll be the easiest and cheapest solution, good point about not forgetting!

@stoveliker - I assumed the warm air from my house would want to rise out through the chimney and keep the cold air from sinking.

@begreen - Leaky upstairs turning the house into a chimney makes sense, that's probably what's happening, and ties in with @stoveliker's sinking cold air comment. We don't have air sealing in the attic and scarce insulation. We need to get the vermiculite/asbestos remediated before tackling that unfortunately.

@NewGuy132 - Clinton, how about you? Do you have a favorite wood guy, esp. for fully seasoned and reasonably fair cords?

@mikey - The cold air's coming down the chimney. I can close the bypass and the air intake, but there's no way to close it completely. Closed bypass just pushes air through the catalysts, and the air intake doesn't shut 100% I assume to prevent backdrafts. We don't have a damper on the stovepipe. Should we have one? Might be safer than stuffing towels up there.

@Eman85 - Our house is basically like a 1.75-story Monopoly house. The stove's on the first floor with chimney coming out the side of the house and going up past the low drip edge then up another ~8' to the cap. Our roof is 12:12, the cap is probably within 1-2 feet of the roof's peak.

 

[NewGuy132]

Thanks for the great responses!

@Kevin Weis - thanks, stuffing the chimney in the off season seems like it'll be the easiest and cheapest solution, good point about not forgetting!

@stoveliker - I assumed the warm air from my house would want to rise out through the chimney and keep the cold air from sinking.

@begreen - Leaky upstairs turning the house into a chimney makes sense, that's probably what's happening, and ties in with @stoveliker's sinking cold air comment. We don't have air sealing in the attic and scarce insulation. We need to get the vermiculite/asbestos remediated before tackling that unfortunately.

@NewGuy132 - Clinton, how about you? Do you have a favorite wood guy, esp. for fully seasoned and reasonably fair cords?

@mikey - The cold air's coming down the chimney. I can close the bypass and the air intake, but there's no way to close it completely. Closed bypass just pushes air through the catalysts, and the air intake doesn't shut 100% I assume to prevent backdrafts. We don't have a damper on the stovepipe. Should we have one? Might be safer than stuffing towels up there.

@Eman85 - Our house is basically like a 1.75-story Monopoly house. The stove's on the first floor with chimney coming out the side of the house and going up past the low drip edge then up another ~8' to the cap. Our roof is 12:12, the cap is probably within 1-2 feet of the roof's peak.

I am from Westboro. There is another guy on here from Westboro, and I think someone from Marlboro. As far as wood goes I am 99% sure that we all just get logs and process it ourselves. Last year I bought a couple cords from a company our of Spencer I think and not only was it short probably 1/3 of a cord, but it still isn't seasoned a year later.

Oh also to add this smell happened to me the other weekend when it got nice out. I opened up the damper on my stove and it seemed to go away. I think that due to the design of my stove leaving the damper open is key to not getting the downdraft smell.

 

[kborndale]

Thanks for the great responses!



@NewGuy132 - Clinton, how about you? Do you have a favorite wood guy, esp. for fully seasoned and reasonably fair cords?

The only way to get fully seasoned wood is to buy it a year or two in advance and season it yourself. The chance of buying ready to burn wood is slim to none.

 

[begreen]

There are other factors that can cause downdraft. Two more are chimney location in relation to the house, and geographic location. For example, chimneys in the one-story section of a house that has a larger 2 story section can often perform poorly. Houses located where there is a strong positive pressure caused by the wind can also have issues with downdraft.

Here's a good article on this topic.

A non-commercial service in support of responsible home heating with wood - How Wind Affects Chimney Performance

The Wood Heat Organization was formed to support the public in the responsible use of wood energy in the home. We fulfill our mandate by providing reliable information, by conducting research into wood heating-related issues and by representing the public interest in discussions of policies that...

woodheat.org

Another one about draft issues.

Sweep's Library - Troubleshooting Chimney Draft Problems

Improving chimney updraft

hearth.com

 

[wetwood4life]

I actually used to work down that way and lived right near the old Marlborough airport. I hear they've sold it to a developer unfortunately - "progress".

Our property is tiny and really can't support firewood processing. Last year we bought 2 cords fully seasoned. It was a generous 2 cords, but only half was burnable. This year we bought 1 cord from another supplier and it was 1/3 short like yours. From the weight I doubt it's fully seasoned. When I asked the guy about being 1/3 short he lost it. Makes no sense. If you're going to rip off all your customers and most don't notice/care, just apologize and top up the 5% who actually call you out.

 

[RomanW]

Another one about draft issues.

Sweep's Library - Troubleshooting Chimney Draft Problems

Improving chimney updraft

hearth.com

I'm having issues with this as well. The downdraft is really bad when my chimney is cold. Has anyone ever tried the gelled alcohol trick? That sounds like a really good method to remove a smoke issue while trying to remove the cold air plug in the chimney...

 

[Kevin Weis]

Forgot to add if you have an outside clean out below the tee, leave that open and most of the downdraft will/may go out the clean out. Unless you have an hermetically sealed stove whereby you can close off air 100%, just by closing the stove won't do it and you can't alter the chimney otherwise either leaves you few other choices.

 

[Lightfan]

Forgot to add if you have an outside clean out below the tee, leave that open and most of the downdraft will/may go out the clean out. Unless you have an hermetically sealed stove whereby you can close off air 100%, just by closing the stove won't do it and you can't alter the chimney otherwise either leaves you few other choices.

I'm having issues with this as well. The downdraft is really bad when my chimney is cold. Has anyone ever tried the gelled alcohol trick? That sounds like a really good method to remove a smoke issue while trying to remove the cold air plug in the chimney...

Hi,

Just tried to light my stove. Really difficult. Very bad down draft despite having the chimney swept yesterday. Eventually got stove lit, however whist its warm/ hot not like its usual furnace even when vent fully opened. HELP!

 

[Rich L]

I resolved my basement downdraft issue by buying a stove large enough to give me 14 hrs of heat. That heat time gives me enough time to reload the stove before it cools off creating a downdraft.