Hi, all. I came across this forum in my never ending search of the internet for an answer to my issue. Simply put, my exhaust smoke smells bad. It doesn’t smell like wood stove from the chimney. Chimney is all clean and fresh swept. Wood is decent at 19-20%The stove smells fantastic inside (When I open door to load it) But outside the smoke from the chimney smells gross. Almost metallic? Very pungent Have tried running stove low and high. As the fire burns down to embers it will start to smell like proper woodstove smoke outside. What’s causing this? Is the smoke too hot when it vents out the chimney cap? Too cold? I’ve taken the whole system apart an cleaned it all really well. (Brushed up Inside the stove too). It didn’t solve any of the issues. Again, stove smells proper inside, only the chimney exhaust stinks.
Stinky smoke
- Thread starter Mrcanoe
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On a cold day do you see lots of white smoke?. Usually stinky smoke is sign of too much moisture in wood or improper burning. Any chance you hear hissing from the wood?
Can you be more specific about improper burning? I’ve tried so many different combinations of draft setting and it changes nothing. I hear the odd hissing if I bring in fresh wood with some surface moisture on it from outside (I do keep my wood covered). However this smell is produced even with wood that has been sitting indoors for 2+ years (12-14% moisture) I have even tried different suppliers, initially thinking it was my wood.
Since we really dont know anything about the stove and its internal configuration, its hard to make a guess. It could be crappy design or some internal component out of place/missing. Generally, smell implies poor combustion and poor combustion is related to peak combustion temperature and enough turbulence to ensure all the gases meet or exceed the peak temperature. In most stoves, combustion temps are tied to air flow or the amount of vapor being generated by moisture in the wood.
Moisture in wood is in its liquid phase even if you cannot see it. 10 pounds or wood @20% moisture content has 2 pounds of water in it. Even pound of liquid water absorbs 1000 btus of latent (hidden heat) to turn into water vapor that goes up the stack. That heat has to come from somewhere so it cools down the gases in the stove. That latent heat is lost to the stove and hopefully the stack as if it cools back to down to liquid form inside the chimney it causes lots of creosote issues.
Not enough air flow in the right place is the second issue, If there is not enough oxygen in the combustion zone the various carbon chains in the fuel will not combust fully forming incomplete combustion byproducts. The simplest one is Carbon Monoxide but that is just one of many and the other ones do have an odor as anyone with an outdoor boiler will know when it chokes down the airflow when there is no heating demand. The OWBs stack is much lower to the ground than a typical woodstove but a woodstove can do the same thing its just that with a higher exhaust point the odor gets diluted.
My advice is start with kiln dried wood or biobricks and make sure that moisture is not the issue. If its a stove issue, its going to be very hard to diagnose from afar or even in person unless some pretty exotic equipment is used, like an extractive gas probe and high temperature thermoprobes to get internal temperatures.
Moisture in wood is in its liquid phase even if you cannot see it. 10 pounds or wood @20% moisture content has 2 pounds of water in it. Even pound of liquid water absorbs 1000 btus of latent (hidden heat) to turn into water vapor that goes up the stack. That heat has to come from somewhere so it cools down the gases in the stove. That latent heat is lost to the stove and hopefully the stack as if it cools back to down to liquid form inside the chimney it causes lots of creosote issues.
Not enough air flow in the right place is the second issue, If there is not enough oxygen in the combustion zone the various carbon chains in the fuel will not combust fully forming incomplete combustion byproducts. The simplest one is Carbon Monoxide but that is just one of many and the other ones do have an odor as anyone with an outdoor boiler will know when it chokes down the airflow when there is no heating demand. The OWBs stack is much lower to the ground than a typical woodstove but a woodstove can do the same thing its just that with a higher exhaust point the odor gets diluted.
My advice is start with kiln dried wood or biobricks and make sure that moisture is not the issue. If its a stove issue, its going to be very hard to diagnose from afar or even in person unless some pretty exotic equipment is used, like an extractive gas probe and high temperature thermoprobes to get internal temperatures.
Literally the last post before yours they said it even happens with 2 year old wood that is 12-14%.
Buy some hickory, nothing smells better. Many species of wood don't smell good when burning, blame it on their DNA.
Several woods will have that "acidry" smell to it when burned. Especially the hedge woods like Locust and Osage Orange. Your "sweeter" smelling woods are usually your nut woods like Oak and Hickory and of course your fruit woods like Cherry' Apple etc.
I find the exhaust from my two epa stoves (1 cat, 1 tube) to be less pleasant than the exhaust from my non-epa fireplace. The fireplace smells like a good campfire. The other two are more acrid, somewhere between the campfire and the very strong smell of burning creosote. Using the same wood for all 3. I'd also say that the epa stoves smell worse with higher moisture fuel.
I'm burning lodgepole pine mainly. All you easterners found out what that smells like when Canada caught fire last summer!
I'm burning lodgepole pine mainly. All you easterners found out what that smells like when Canada caught fire last summer!
My cat stove smells worse than my previous non-epa stove. During the first half of the burning cycle….
All I can think is the exhaust during the first half has more moisture in it. I don’t get “smoke” from my chimney except on start up
All I can think is the exhaust during the first half has more moisture in it. I don’t get “smoke” from my chimney except on start up
sneefy
Burning Hunk
When mine (Lopi Evergreen) is burning efficiently, hot and clean with no smoke coming from the chimney and only heat waves, it smells like you describe. It only smells good when there's visible smoke and that only happens during startup. I burn a mix of oak, ash, a little pine, and pressed logs.
I think inefficient and incomplete burning sends up a lot of the more pleasant smelling particulates. When the burn is clean, and the reburn tubes or the cat are doing their job, those particulates are consumed and there's not much left that actually smells good.
That's my theory, anyway.
I think inefficient and incomplete burning sends up a lot of the more pleasant smelling particulates. When the burn is clean, and the reburn tubes or the cat are doing their job, those particulates are consumed and there's not much left that actually smells good.
That's my theory, anyway.
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What makes the smell of wood is Polyaromatic Hydro Carbons. They will burn if exposed to sufficient heat. PAHs is what makes smoked meat taste smoked.
sneefy
Burning Hunk
Sure, but it's the aromatics in the wood that give it flavor and make it taste/smell like hickory, apple, mesquite, etc. That's probably what give the smoke it's appealing smell as well. Or, are you concurring that those are what is getting burned off and thus the aromatic smell is gone?
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