Pellet Stove Exhaust Under Wood Decking

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medrestore

New Member
Jan 24, 2022
1
georgia
I want to install a pellet stove in the basement, where the exhaust will come off the stove, go up about 2' turn and go out of the wall with a 2' piece. The problem is the decking above that spot. To clear the deck, I would need to go up 2' and then out about 8 '.
If I use double wall 4" pipe, is this distance okay or would this be a fire hazard
 
As long as you maintain proper clearance I see no problem
 
Granted I have zero pellet stove experience, I'd want to be able to see the exhaust. Why? Because trouble often shows at the exhaust. Having it under a deck (even if code compliant) prevents one from doing that. So why not add a 90 degree and exhaust above the deck.
 
Horizontal for 8 feet? That sounds like a very bad idea.
If going that far horizontal, it's important to have it at least tilt uphill. If it exits under the deck, and it's just a short horizontal to there, you may well get sparks exiting -- not generally the hottest, but still sparks. Assuming you're not using the deck in heating season, what about putting a hatch in it and putting a vertical pipe up through, which can be removed in deck season. I can't imagine you want to be up on a deck with smoke rising through the boards anyway.
 
It would be helpful if you shared some pictures of the deck at the location you want to install the pipe.

I like whit's idea of the hatch. During the heating season have it come out and then up through the deck and up for a ways above it.

During the off-season, take the pipe down and plug the pipe coming out of the house with a Fernco cap, so it's water tight and won't need to be looked at until you're ready to turn the stove on in the fall.
 
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I want to install a pellet stove in the basement, where the exhaust will come off the stove, go up about 2' turn and go out of the wall with a 2' piece. The problem is the decking above that spot. To clear the deck, I would need to go up 2' and then out about 8 '.
If I use double wall 4" pipe, is this distance okay or would this be a fire hazard
What does your stove installation manual say? My manual (for a Pelpro 130/60) says 12 inch vertical clearance for the vent termination if under a deck. It does not mention anything about having to clear the entire width of the deck, i.e, the termination has to stick out the other side of the deck.
 
As a service tech I would want the exhaust in a accessible place. When I walk up on a call for a stove issue the first thing I do before walking into the house is pop the term cap off to check cleanliness of pipe and cap. This is a prime example. Customer complaint was that the stove would take a long time to light but would not stay running. He swore his auger motor was going out. :). Before I walked inside and started disassembling the stove and checking for voltage or doing a draft test ect. I pulled the cap and determined that there was a good chance the stove was fine and just needed cleaned.

[Hearth.com] Pellet Stove Exhaust Under Wood Decking
 
As a service tech I would want the exhaust in a accessible place. When I walk up on a call for a stove issue the first thing I do before walking into the house is pop the term cap off to check cleanliness of pipe and cap. This is a prime example. Customer complaint was that the stove would take a long time to light but would not stay running. He swore his auger motor was going out. :). Before I walked inside and started disassembling the stove and checking for voltage or doing a draft test ect. I pulled the cap and determined that there was a good chance the stove was fine and just needed cleaned.

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I am not sure how your response relates to OP's question? I think he was concerned about clearing the deck as it could be a fire hazard if the exhaust terminates below the deck.
 
Pretty sure any building code prevents you from putting one under a deck unless its a deck that's 8 foot off the ground.
 
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Pretty sure any building code prevents you from putting one under a deck unless its a deck that's 8 foot off the ground.
I have no idea about building code. I just think what OP was asking can be a common case. I mean a lot of houses have walkout basements, and a deck on top of the walkout. This is a popular configuration where I live.

So if someone like OP wants to put a stove in the basement, they will have to think about where the terminate can be. Chances are it will be exiting the wall under the deck. And the deck typically is 8 to 10 feet wide from the wall. So I can understand the OP's concern of this being a fire hazard.

The installation manual of my stove only calls for 12 inch clearance between the deck and the termination, which I was not expecting.
 
I am not sure how your response relates to OP's question? I think he was concerned about clearing the deck as it could be a fire hazard if the exhaust terminates below the deck.
The original post does not state the exact reason for concern or many details. Is the deck 2 ft off the ground or 8ft off the ground? The point I was making is the termination needs to be accessible. You would not want to be belly crawling back under a deck to service the pipe. And as we all know the pipe needs serviced regularly.
 
As a service tech I would want the exhaust in a accessible place. When I walk up on a call for a stove issue the first thing I do before walking into the house is pop the term cap off to check cleanliness of pipe and cap. This is a prime example. Customer complaint was that the stove would take a long time to light but would not stay running. He swore his auger motor was going out. :). Before I walked inside and started disassembling the stove and checking for voltage or doing a draft test ect. I pulled the cap and determined that there was a good chance the stove was fine and just needed cleaned.

View attachment 290812
I have had a couple of vent pipe fires when the stove is cranked after a couple months of low fires. The creosote at the termination catches. Not a big deal, but I would be concerned if the termination is under a deck and there are actual flames coming out of the vent.
 
I have had a couple of vent pipe fires when the stove is cranked after a couple months of low fires. The creosote at the termination catches. Not a big deal, but I would be concerned if the termination is under a deck and there are actual flames coming out of the vent.
Thats not good. You need to crank it up more often to keep the creosote from building up. Or run it hotter for shorter times.
But yes that is a very good point
 
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Thats not good. You need to crank it up more often to keep the creosote from building up. Or run it hotter for shorter times.
But yes that is a very good point
I heated with wood for many years and that was the one thing I did every single morning. 15 years ago, when I bought my first pellet stove, the word was that I didn't have to worry about creosote. Getting a call from my wife that there were flames coming out of the vent changed my thinking real quick. I sold the old stove (which was the root cause of the creosote due to poor design) and bought a Harman Accentra. I turn it down at night but when I turn it up in the morning it cranks for an hour to an hour and a half. I religiously check the exhaust venting and in the 3 years I've owned it, I've never seen any buildup on the termination. Still, that's me. Judging by your picture, it's not an all too uncommon problem.
 
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The original post does not state the exact reason for concern or many details. Is the deck 2 ft off the ground or 8ft off the ground? The point I was making is the termination needs to be accessible. You would not want to be belly crawling back under a deck to service the pipe. And as we all know the pipe needs serviced regularly.
I see. That makes sense. Thanks for the explanation. I just assumed OP has an 8ft deck off the ground. Hard for me to imagine why someone will run a pipe under a 2 ft deck? I mean the exhaust port in the back of the stove is already 1-2 ft off the floor already?
 
I heated with wood for many years and that was the one thing I did every single morning. 15 years ago, when I bought my first pellet stove, the word was that I didn't have to worry about creosote. Getting a call from my wife that there were flames coming out of the vent changed my thinking real quick. I sold the old stove (which was the root cause of the creosote due to poor design) and bought a Harman Accentra. I turn it down at night but when I turn it up in the morning it cranks for an hour to an hour and a half. I religiously check the exhaust venting and in the 3 years I've owned it, I've never seen any buildup on the termination. Still, that's me. Judging by your picture, it's not an all too uncommon problem.
I learned something new here today. So what you are saying is, run the stove at high heat for an hour or so to use the hot exhaust to burn off the creosote buildup?
 
I learned something new here today. So what you are saying is, run the stove at high heat for an hour or so to use the hot exhaust to burn off the creosote buildup?
I guess my answer is it depends. My venting comes out the back of the stove and goes up 8 feet then a 90 out through the wall to the termination about 18 inches out from the house. Creosote forms when the exhaust is cooled and the moisture in the exhaust condenses on the cold pipe. Over time it builds up. Especially on the screening at the end of the cap. When you crank the stove the exhaust is hot even out to the termination. If it's hot enough it will cause the creosote to expand and turn to ash. That ash can be brushed away. Now if you have venting that goes straight out the back or is not long the exhaust usually doesn't cool as much so there is not as much condensation. That said, cranking the stove for an hour every morning can't hurt
 
My stove vents under my deck. I have 3' of vertical clearance from the deck and 2' of horizontal clearance from the house. The building inspector approved and his only comment was that there needs to be good air circulation under the deck.
 
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I see. That makes sense. Thanks for the explanation. I just assumed OP has an 8ft deck off the ground. Hard for me to imagine why someone will run a pipe under a 2 ft deck? I mean the exhaust port in the back of the stove is already 1-2 ft off the floor already?
Right, We dont know if it is a walk out, split level or full depth basement. I have seen some pretty shady unsafe stuff.
 
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I learned something new here today. So what you are saying is, run the stove at high heat for an hour or so to use the hot exhaust to burn off the creosote buildup?
If the stove is idling for extended periods of time yes it is good to crank it up regularly. Before I converted my P38 to a P43 auto ignite, I would keep it on a low fire to maintain temp in the basement, So it was burning at a low temp 24/7. Then one day I kicked it up and had a small chimney fire. That is when I converted it so it runs for a period of time then goes into chit down then refires when needed. So it is burning at a higher temp when it is running.
 
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If the stove is idling for extended periods of time yes it is good to crank it up regularly. Before I converted my P38 to a P43 auto ignite, I would keep it on a low fire to maintain temp in the basement, So it was burning at a low temp 24/7. Then one day I kicked it up and had a small chimney fire. That is when I converted it so it runs for a period of time then goes into chit down then refires when needed. So it is burning at a higher temp when it is running.
I do a similar thing. Room temp, feed on 4 and set the temp. 67 during the day, 60 at night. It really cranks in the morning when I turn it up.
 
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