Smoky oak

[chimneybrush]

We had a stove shop install a harman p38 this summer. Stove is 4 years old, vent goes thru the wall. After they left it started smoking in the small room where it is. Can't see the smoke but can smell it. They came back and taped up the indoor exhaust pipe, also 4 years old. It helped some but after they left it started smoking again. So we called them back and they replaced the inside pipe with a new one, and extend the outside pipe a few inches. After they left it started smoking again.

I removed the OAK tube, which is smaller than the wall fixture, they had taped that up too, i capped off the wall fitting. Now it doesn't smoke in the room any more where the stove is.

Instead smoke comes in whatever windows are downwind. Not bad, but sometimes the bedroom, sometimes where the dog sleeps. With a breeze we don't get any smoke but the wind dies at night and we're getting it in other parts of the house.

Here are pics of the wall fixture. I think there is something wrong with it, either the 2 pipes are too close and the oak sucks in smoke, or something. In the outdoor shot the small hat above the pipe covers a long slot for the air intake, I'm thinking it funnels in the smoke. Is this a poor design, is there a better way to do this?




Thanks for any help

 

[Mt Bob]

I never liked that style of wall thimble.I prefer ones that the fresh air is below the flue pipe.However you need to run the oak as you are creating a bigger suction within your house.When hooked up you would never smell anything as it is being sucked into stove.Startups and shutdowns may cause smell,though.With the oak unhooked enough suction is being created to draw in from every small crack,but in certain wind conditions,with the best install,this may happen anyway.Sounds like you need to do some window work.Best for you might be to run flue above roof edge,but if was mine,being winter,I would add a 90 and go up about 4 foot and see how it does.Also you have wood stoves,do they have oak?

 

[BUBIBEAR]

Bob bare is right on both counts. Need more hight on the outside for better draft .

 

[womaus]

Here are pics of the wall fixture. I think there is something wrong with it, either the 2 pipes are too close and the oak sucks in smoke, or something. In the outdoor shot the small hat above the pipe covers a long slot for the air intake, I'm thinking it funnels in the smoke. Is this a poor design, is there a better way to do this?

I just installed my Harman Accentra with the same type of wall thimble, a bit differently.

From the stove I go straight out through the wall using DuraVent 3". The connector to the stove plus the straight pipe gives it an 18" horizontal run through the wall to the T connector located outside of the house, then a couple of lengths of vertical pipe, then the 90, then the vent cap. This brings the vent outlet about 32" up and away from the intake integrated into the wall thimble. So far no issues with smells or smoke, and a nice clean fire in the pot.

With your configuration I would add at least 24" to the vertical rise, it may do the trick. Will also help (I think) in the event of a power outage, the more vertical the better the draft to keep the smoke going out.

 

[Deezl Smoke]

The thimble is'nt the problem, but the outlet point sure is. You have a large window far too close for that outlet point, and the foundation should have vents in it. Likely smoke can get under the house and show up in any room. IMO, definitely need to get that outlet away from that window.

 

[Wilbur Feral]

...but if was mine,being winter,I would add a 90 and go up about 4 foot and see how it does.

Yep

 

[womaus]

The thimble is'nt the problem, but the outlet point sure is. You have a large window far too close for that outlet point, and the foundation should have vents in it. Likely smoke can get under the house and show up in any room. IMO, definitely need to get that outlet away from that window.

Are the windows original to the house? If so, how tight are they within the casements?

This may sound like a foolish question, but do you have windows cracked open still? We've been in a very mild late year here on the east coast, we still occasionally open the windows on the warmer days, sometimes forgetting to shut them.

All houses have negative pressure due to clothes dryers, oil burners, gas burners, range hoods, anything that vents out of the house. Makeup air needs to come from somewhere, that is what becomes the draft you feel. If the windows are loose in the casements you'll get the outside air coming in...if near or downwind from the outlet vent there is the chance of the flavored air getting back into the house.

As others stated above, the OAK itself is not the actual problem you have, in fact it is part of the solution. It's better to bring in cold outside air for the combustion of the pellets, you're not using the internal house air and exhausting it outside of the house, the OAK will reduce the negative air issue.

With my wall thimble, and I believe it may be the same as yours, I have found that the adjustable intake area has a bit of a "leak" area due to the ability to twist the intake to meet up correctly with the air intake on the stove. You could be getting some flavored air in through there.

I used automotive flex exhaust tubing along with a pipe reducer (all found at a local auto parts store) to make the OAK connection. Everything sealed with high temp silicone fusible tape. Worked for me.

My exhaust is well within 12" of of a couple of windows that do not open. No issues there. The windows are original to the house, 5 years short of 100 years old. All other windows are double pane replacements, and the house was somewhat recently dosed with blown in insulation.

Most utility companies now will provide an energy assessment, effectively sealing up areas of the house and providing the equipment to create a positive air flow, to be able to see where the leaks are. You may want to look into that...then address the obvious issues.

 

[chimneybrush]

I reinstalled the oak tube, pushed it in far as i could wrapped it with aluminum tape from the hardware store "made in the usa." Ran it overnight quit smoking almost all the way. Pellet smoke only comes in right behind the stove by the pipes after it's been running a few hours.
I think the problem is sucking in smoke and leaking at the intake. Will check the joint at the stove next, a tight squeeze down there. Maybe the tube is leaking, it is 4 years old, will see about a new one.
Will look at running the outside pipe up, cat sleeps upstairs don't want to smoke her out tho.
No pellet smoke thru the windows, just wood smoke. Connecting the oak helped with that, the end of the tube was sucking almost like a vacuum cleaner. No more house shuddering just a little at the stove once in a while.
Windows are 20 years or newer, house 40 years with good insulation, we added some blown foam, vents are clear
thanks for the help

 

[alternativeheat]

We had a stove shop install a harman p38 this summer. Stove is 4 years old, vent goes thru the wall. After they left it started smoking in the small room where it is. Can't see the smoke but can smell it. They came back and taped up the indoor exhaust pipe, also 4 years old. It helped some but after they left it started smoking again. So we called them back and they replaced the inside pipe with a new one, and extend the outside pipe a few inches. After they left it started smoking again.

I removed the OAK tube, which is smaller than the wall fixture, they had taped that up too, i capped off the wall fitting. Now it doesn't smoke in the room any more where the stove is.

Instead smoke comes in whatever windows are downwind. Not bad, but sometimes the bedroom, sometimes where the dog sleeps. With a breeze we don't get any smoke but the wind dies at night and we're getting it in other parts of the house.

Here are pics of the wall fixture. I think there is something wrong with it, either the 2 pipes are too close and the oak sucks in smoke, or something. In the outdoor shot the small hat above the pipe covers a long slot for the air intake, I'm thinking it funnels in the smoke. Is this a poor design, is there a better way to do this?

View attachment 168923
View attachment 168924

Thanks for any help

I think I'd be looking at that window right there level with your vent and any others near by like that one. And I like the idea of going up with the vent outside as well. My own vent goes 23 ft up and out an existing chimney, so clears the roof line ( required 4" vent).. had I run out the side wall it would have been right into the prevailing NW winter winds, not so great a deal. Even if your OAK sucked in some smoke it would be burned in the combustion process anyway not admitted to room air. Your thimble could leak though.

 

[sparklow]

You need some venting ...

 

[Mt Bob]

I reinstalled the oak tube, pushed it in far as i could wrapped it with aluminum tape from the hardware store "made in the usa." Ran it overnight quit smoking almost all the way. Pellet smoke only comes in right behind the stove by the pipes after it's been running a few hours.
I think the problem is sucking in smoke and leaking at the intake. Will check the joint at the stove next, a tight squeeze down there. Maybe the tube is leaking, it is 4 years old, will see about a new one.
Will look at running the outside pipe up, cat sleeps upstairs don't want to smoke her out tho.
No pellet smoke thru the windows, just wood smoke. Connecting the oak helped with that, the end of the tube was sucking almost like a vacuum cleaner. No more house shuddering just a little at the stove once in a while.
Windows are 20 years or newer, house 40 years with good insulation, we added some blown foam, vents are clear
thanks for the help

OK you made progress.First,you are getting no smoke from the inlet.When stove is running the inlet is under slight vacuum all the way out the tube to outside.Would not even matter if you had a hole in it.Would only cause a problem if stove was off but still smoldering.Your problem is probably at the stove to pipe adapter.There is a gasket there.Also the stove adapter to pipe adapter is a stupid tapered thing,and sometimes installers use the wrong pipe adapter,or damage the right adapter.Has happened many times,even to where smoke goes between the layers of pipe.Wrong screws can also cause problems.On my personal stove I welded 4" exhaust pipe to stove adapter,then used slip on connection,hose clamp no screws,very easy to r&r.

 

[rona]

I reinstalled the oak tube, pushed it in far as i could wrapped it with aluminum tape from the hardware store "made in the usa." Ran it overnight quit smoking almost all the way. Pellet smoke only comes in right behind the stove by the pipes after it's been running a few hours.
I think the problem is sucking in smoke and leaking at the intake. Will check the joint at the stove next, a tight squeeze down there. Maybe the tube is leaking, it is 4 years old, will see about a new one.
Will look at running the outside pipe up, cat sleeps upstairs don't want to smoke her out tho.
No pellet smoke thru the windows, just wood smoke. Connecting the oak helped with that, the end of the tube was sucking almost like a vacuum cleaner. No more house shuddering just a little at the stove once in a while.
Windows are 20 years or newer, house 40 years with good insulation, we added some blown foam, vents are clear
thanks for the help

I would add 12 inches to the exh pipe before that endcap. That should keep the exh from being sucked in the OA system. adding two 90 degree elbows plus 3 feet outside might make a draft to help if power goes out but you can be sure you will be cleaning the bottom elbow twice or more often during the season. Reason being the exh will be cooled off by the winter temps. It will be cheaper to buy a 12 inch pipe then the other assorted pipes and elbows.

 

[womaus]

This is my own installation. Again, I hope the inspector finds it acceptable, I've got 24" between the exhaust outlet and the OAK inlet. I've got a couple extra 12" pipes if needed...maybe I should get them configured, lengthen the stack.

 

[alternativeheat]

I would add 12 inches to the exh pipe before that endcap. That should keep the exh from being sucked in the OA system. adding two 90 degree elbows plus 3 feet outside might make a draft to help if power goes out but you can be sure you will be cleaning the bottom elbow twice or more often during the season. Reason being the exh will be cooled off by the winter temps. It will be cheaper to buy a 12 inch pipe then the other assorted pipes and elbows.

Yeah and I have concerns that this exhaust is already up and out as it. To add a T outside and go up again might be starting to restrict it a bit without going 4" pipe for the rest of the rise.

 

[alternativeheat]

This is my own installation. Again, I hope the inspector finds it acceptable, I've got 24" between the exhaust outlet and the OAK inlet. I've got a couple extra 12" pipes if needed...maybe I should get them configured, lengthen the stack.

View attachment 168993

Womaus, if you look at an Accentra FS install sheet you might find that the outlet is to close to those windows, being that I assume the windows are functionally able to open and the outlet is right under them. Check your instructions. Here is a link to the downloadable PDF manual if you don't have one: (broken link removed)

 

[womaus]

Womaus, if you look at an Accentra FS install sheet you might find that the outlet is to close to those windows, being that I assume the windows are functionally able to open and the outlet is right under them.

These windows are non-functional, fully sealed. I fully checked on this, dealing with a possible new purchase and dealer installation. Both verified no issues.

I decided to go with a used Accentra after seeing close to a $5K purchase price for new with installation.

Good thoughts though, thanks for the concern.

 

[alternativeheat]

These windows are non-functional, fully sealed. I fully checked on this, dealing with a possible new purchase and dealer installation. Both verified no issues.

I decided to go with a used Accentra after seeing close to a $5K purchase price for new with installation.

Good thoughts though, thanks for the concern.

That's why I said "assuming", LOL! One never knows. Nice looking install by the way.

 

[chimneybrush]

I think we found the problem. The intake pipe wasn't hooked up to the stove inlet. So much for a professional installation.

I'm surprised it wasn't smoking more. I was pretty sure it had something to do with the intake pipe, had no idea it wasn't connected. Taped it up for now, so far so good. thanks for the help.

 

[alternativeheat]

I think we found the problem. The intake pipe wasn't hooked up to the stove inlet. So much for a professional installation.
View attachment 168994
I'm surprised it wasn't smoking more. I was pretty sure it had something to do with the intake pipe, had no idea it wasn't connected. Taped it up for now, so far so good. thanks for the help.

No seems unlikely, the intake draws air in not pushes smoke out. But looking at your exhaust pipe I see a trail of ash that appears to be coming from where the pipe connects to the stove. I bet that joint is not sealed. And actually in looking closer it more looks like the flange is leaking rather than the exhaust pipe.

 

[Deezl Smoke]

I guess someone might be able to do such a good job of applying sealant that it is not noticeable, but I mostly doubt it. Each of these joints needs a high temp sealant applied. A screw only keeps it from coming apart unintentionally. It does nothing for sealing the joint no matter the gasket inside the piping.

 

[Mt Bob]

ok done here,poster has not learned gas cannot escape when under vacuum,do not recognise the pipe or adapter,screw placement would make me take it all apart and inspect.As to deezl,I have (and am still) using pipe to stove adapters,with no sealer,for a while.Not everything in the world needs to be glued.As we say in the automotive business,it should not leak without sealer,but sealer will make the seal last longer.

 

[womaus]

ok done here,poster has not learned gas cannot escape when under vacuum,do not recognise the pipe or adapter,screw placement would make me take it all apart and inspect.As to deezl,I have (and am still) using pipe to stove adapters,with no sealer,for a while.Not everything in the world needs to be glued.As we say in the automotive business,it should not leak without sealer,but sealer will make the seal last longer.

What I find concerning is the opening sentence of this thread:

We had a stove shop install a harman p38 this summer.

I would be on the phone to that stove shop pronto...

 

[bogieb]

Plenty of people run without an OAK hooked up, so unless there is something seriously wrong with the stove, the fact that the semi-rigid duct pipe was not hooked to the stove should not account for smoke.

The end of the T is notorious for leaking (I see they sealed the joint of the T, but not the end). Use silicon tape to seal up the end of the T, and as others have pointed out, seal up the rest of the joints that are inside the house. Silicone tape is cheap, comes in several colors so you can make it almost unnoticeable, easy to apply and easy to remove if so needed.

What I find concerning is the opening sentence of this thread:

We had a stove shop install a harman p38 this summer.

I would be on the phone to that stove shop pronto...

This is an even better place to start - you, as a novice, should not be chasing this issue by yourself since you didn't install it!

 

[womaus]

Plenty of people run without an OAK hooked up, so unless there is something seriously wrong with the stove, the fact that the semi-rigid duct pipe was not hooked to the stove should not account for smoke.

But, if there was a nearby clear and open path to outside air that terminated quite close to the exhaust vent, could the negative air pressure caused by the stove suck some of the exhaust back in the house? With the intake ducting not tied in securely to the stove I imagine there could be some leakage there? Sort of like leaving a window cracked a bit near an exhaust? Wouldn't happen all of the time I imagine, but under the correct wind/weather conditions?

I agree with you fully that the obvious is the exhaust pipe, seams, gaskets, etc due to these being under positive exhaust air pressure.

 

[bogieb]

But, if there was a nearby clear and open path to outside air that terminated quite close to the exhaust vent, could the negative air pressure caused by the stove suck some of the exhaust back in the house? With the intake ducting not tied in securely to the stove I imagine there could be some leakage there? Sort of like leaving a window cracked a bit near an exhaust? Wouldn't happen all of the time I imagine, but under the correct wind/weather conditions?

I agree with you fully that the obvious is the exhaust pipe, seams, gaskets, etc due to these being under positive exhaust air pressure.

Well, that is an interesting theory and after reading the original post, it seems that it may have something to do with at least part of the infiltration. Especially since the infiltration started at random areas in the house after the OAK was disconnected and capped.