Nasty Smell caused from rain or snow going down flu

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dboone

Member
Nov 22, 2008
45
Western Missouri
I am nearly positive I saw a thread on this subject, but could not come up with the right words to find it. I have not burned for a couple weeks. Sometimes now when it rains, I assume some moisture is going down the flu and causes and nasty smoke smell. This smell works its way through the whole house. I do have a chimney cap and the air control is shut all the way. I have not yet removed the ash from the last burn. Is the moisture reacting with the soot or creosote in the flu? Any suggestions for eliminating or minimizing this?
 
Wow! BeGreen you have a good memory. I posted the thread you referenced in December and since then it seems the problem with smoke escaping has decreased. I would think mostly because I was getting the hang of it.

Please explain how the negative pressure would be related to the problem I am having. Is this negative pressure sucking air through the flew & stove and into the basement? What are the remedies?
 
dboone said:
Please explain how the negative pressure would be related to the problem I am having. Is this negative pressure sucking air through the flew & stove and into the basement? What are the remedies?

Yes, the pressure in your basement is probably lower than the air pressure outside. Everything always wants to be at balance, so air flows through the easiest path (hmm 6" chimney) to the lower pressure zone. EPA stoves are never 100% sealed because of the minimum air inlet required even when shut down fully.

How to fix it, well first of all you want your house tight up top and loose on the bottom. If the "top" is loose warm air rises and escapes out through the leaks in the top of the house (can lights, attic access hatches, any holes in drywall for fans, whatever, etc...). Then normally air would leak back in down lower but often times houses are much tighter on the bottom than up top. This creates the a neg pressure in the basement and lower floors. So if you make it tighter up top it will help a lot.

Opening a window in the basement will probably fix it also, but not the best solution. You may be able to consult a HVAC pro for the best way to let extra air into the house. Either a fresh air duct going into the heating return air, or something as simple as a filtered pipe going from outside to inside.

Also you should get your chimney swept very well and clean the inside of the stove. This will help with the smell a great deal. You could probably even put one of those fridge packs of baking soda inside the stove.
 
The best way of killing the summer stink is to get up on the roof and put a cover seal over the flue exit to keep air from being able to come down into the house. I use a piece of sheet metal with some weather stripping and a couple bricks to hold it in place. It's a pain because the cap has to come off first.

I have found that it helps to make sure that the last fire I burn is about as hot as I can get it to basically burn off any creosote. Still, even with that there's still odor on rainy days.

I have heard suggestions like putting a 25 watt light bulb in the stove to create just enough heat to keep airflow going up. I've never tried this one.
 
dboone said:
Please explain how the negative pressure would be related to the problem I am having. Is this negative pressure sucking air through the flew & stove and into the basement? What are the remedies?

Jtp summed this up very well. Here's an article about negative draft. As the weather gets warmer it can be more of a problem. Of course you want to open up windows, probably on the second floor. But the air venting out needs to be replaced with incoming air. In this case, it's sucking some of it back through the stove. Is there an outside air kit connected to the stove?

http://www.gulland.ca/florida_bungalow_syndrome.htm
 
Couldn't you guys have given me a simple answer that takes very little effort to resolve the problem. Negative pressure was not what I had in mind. :) It is hard for me to stomach taking actions that increase cold or hot air from the outside to the basement. It just seems like it is the opposite of what I have always known and tried to do. Tightening the upstairs, now that sounds better, but I am not sure where to start. Am I missing something? If you let outside air in the basement doesn't this defeat your efforts of heating/cooling the house. Would it help with the smell if I was to cover the 3" or so round air intake on the bottom of the stove? The last couple days I have had our HVAC fan running continously. Would this stabilize the pressure throughout the house?
 
I made a plug out of 6" thick foam rubber that fits tightly in the pipe where it passes through the chimney thimble. I install that plug when I'm done burning for the season, and remove it right before the first burn of the next season. To make the foam rubber more airtight, I smeared silicone caulk on one face.

Works great as long as you remember to install it. And remove it!
 
BeGreen said:
Is there an outside air kit connected to the stove?

??
 
Would be nice to have outside air, but do not. The routing of the OAK pipes would be difficult. I wish I would have known about this before building the brick hearth. It would have made the OAK installation easier. Can an OAK draw from the garage?
 
An OAK should not exit in the garage. This is mainly to keep exhaust gasses from entering the house through the OAK.
 
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