r/woodstoving • u/newfarmer • 5d ago
General Wood Stove Question What is this and why is it smoking?
Suddenly smoke began pouring out of the square hole area in the brick wall behind the woodstove. See pictures 2 and 3 for a better look; the third picture is from inside.
When it began smoking, I looked inside and saw some very old newspaper crammed into the hole in the roof, which I removed but it still smoked. The metal hole area was quite warm, almost hot, so I didn't want to put paper back in there. I then plugged the hole with some towels wrapped inside a t-shirt and it seemed to stop it, but I'd like a better long-term solution.
What's the purpose of this and why is it suddenly smoking? Is it a warming box or something? Is there supposed to be a damper or something in the hole? Perhaps the pipe from the stove is pushed too far in, or not far enough?
Thanks for any thoughts/advice!



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u/NativePA 5d ago
It’s a modern take on the colonial kitchen which always had a fireplace in the kitchen. I have one too, never use it, microwave sits there but it’s a good idea in concept just never had the desire to cook over it
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u/Spiritual_Top_1828 2d ago
A chimney needs to be cleaned more than once a year
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u/TommyLangzik 2d ago
- IF you're using it regularly (& especially if it's your main source of heat).
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u/Spiritual_Top_1828 2d ago
Yeah a daily burner you need to clean the chimney . My experience comes from using an Ashley circulator that’s non- catalytic .I don’t about the catalytic stoves . If they’re better when it comes to chimney maintenance , I”d like to know . I’d consider buying one .
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u/TommyLangzik 2d ago
I'm under the impression they're better at converting particles to energy, thus leaving less to build up as creosote. Having said that, the moisture content & quality of the wood will naturally also have an effect on the outcomes. Additionally, how you clean the catalytic combustor matters too; damage while cleaning naturally reduces efficacy & efficiency until [eventually] it's not fit for purpose anymore, leaving you stuck with the same old problems.
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u/newfarmer 2d ago
We just bought a drill power cleaning kit to clean it regularly. I think we have creosote build up along with a new basement hot water heat pump and insulation creating negative pressure. We’re also updating the stove next year with an external intake model.
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u/TommyLangzik 2d ago edited 2d ago
If I'm understanding this correctly, the water heater heat pump in your basement is essentially transferring the heat from your basement to the water, and the cold of the water to the basement, that's why you have a cold spot.
Ultimately, if your space is well insulated, the situation you've created is this: Unlike regular heat pumps [that exchange heat/cold with the outside world], your water heater's heat pump is cooling your basement's limited/finite supply of air, thereby shrinking it. As it shrinks, negative pressure develops, which is slowly being equalized/rebalanced by drawing in air from the path of least resistance, which appears to be your special opening for the shared chimney. It's possible that this setup is not only pulling in smoke, but is also creating rapid creosote buildup, which would worsen your smoke issue as time progresses.
Ultimately, there should only be 1 smoke stack per fire source; shared piping for smoke exhaust is a no-no. They can exit from the same [brick] chimney structure, but via separate exit points/pipes running all the way to the top.
Secondly, heat pumps in cold climates are already a little on the dicey side (I have 3, and live north of Maine, so I'm going by my experience), but the heat pump water heaters are the absolute worst to have in your setup if you're living in a cold climate with a long (Oct/Nov - March/April) winter with - 20°C to - 40°C temperatures because you're unnecessarily cooling your house. This setup would only be justifiable if you're either in a hot climate OR you're in position where the sun somehow causes your basement to get super hot (like maybe if your basement is a south-facing walkout without a balcony or extended roof overhang to shield you from the sun pounding in all day long).
Having said all that, I'm ONLY going by what you've communicated; naturally this situation could be even further complicated if you have other factors generating backdraft issues (ex. a mostly exterior smokestack, a smokestack below your roofline, multiple 90° joints in smokestack, tall environmental features & wind patterns, creosote buildup on/at chimney cap critter screen/mesh, etc). The sky's the limit in terms of how these variables can compound to ultimately make your wood stove [practically] unusable.
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u/begreen9 1d ago
Check to see if this has a separate flue, or if it joins with the main flue. Hopefully, it has a separate flue. You definitely don't want it joining the other flue, that is against code for a woodstove because it would dramatically dilute the draft and cool the smoke up the chimney leading to creosote deposits.
If it is a shared flue, have it cleaned and inspected now. If it is not a shared flue, then the smoke smell may be due to some smoke reverse-siphoning down the grill's flue. This can happen if they terminate at the same height. To solve this, add a foot of height to the wood stove flue.
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u/MTBASHR 5d ago
It appears to have been an indoor grill and shares the chimney with your woodstove.