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Why Does Smoke Exit My Wood Stove When Door Open?
Lately I've been opening the front door of my wood stove to add wood to the fire and smoke has poured out into my house. I have no idea why this is happening. I was wondering if anyone has any advice for me. Thanks.
There may be a few reasons for what you're experiencing. Some will say that it's because your chimney is too short, but I don't know if that's entirely true. I've seen lots of folks make that claim, so I don't want to discount it. It's just that I've never experienced that being the cause. I run two wood stoves in my home and one of them has a relatively short chimney and the other has a much taller chimney. The taller one is the one that smokes when I open the door to load firewood. The only difference between the two stove setups is that one (the taller chimney one) has a few angles in the pipe that leads out through the wall and then a 45 degree angle that goes straight up into the air. On the other stove, it's a straight shot up through the roof. I've rarely ever seen smoke come out of that stove. The draft is great. So angles in your piping can cause a lack of draft.
Regarding draft, if you're not familiar, that's what sucks the smoke and gasses up and out of your chimney. If you've got bad draft, your smoke will sit still and likely come out of your stove and into your house.
One huge factor that might cause smoke is it being too warm outside. I've had both of my stoves smoke when the door is open on warm days. That's simply because there isn't much of a temperature differential between inside your home and outside of it. Chimney draft is created when the inside of the chimney is warm compared to the outside temperate. Heat rises, so if your pipe is hot, that heat will go right out, smoke along with it.
If you've got a new house that's very tight, that can have an effect on draft. Essentially, because the house has no air flow, there's not much air to pull up through the wood stove and out the chimney. For this, I recommend a fresh air vent on your wood stove. Similarly, if you're house is two or more levels and is old and has got lots of air leaks (usually through old drafty windows), you may experience what's referred to as the stack or chimney effect. This occurs when your entire house is acting like a chimney and is pulling the warm inside air out through the upstairs windows. When this happens, the suction comes from down below and a great place for that suction to occur is through your wood stove piping. So if you've got a bad enough situation, you might actually experience a reverse draft, which would be terrible. You would need to take a close look at the efficiency of your home if this were the case.
I like to build small cool fires in my wood stove because many days it's just too warm outside to get a roaring fire going. The problem is, these cool fires never heat up the chimney enough to create a good draft. So when I open the door to add wood, I see all sorts of smoke leave the wood stove and enter my home. Wood stoves like hot fires to operate smoothly and properly. They don't like cool or cold chimneys.
Along the same lines, if you build cool fires, expect to have a clogged chimney cap a lot if you have a spark arrestor screen inside of it. Take a look at the clogged chimney cap post for more information on this. And always make sure your chimney itself is clean. Do this at least once per year and possibly more if you burn a lot of wood every season. It's critical to clean your chimney for safety reasons, but if it gets too clogged, that could be the cause of a poor draft as well. Remember, wet wood smokes a lot and makes for cool fires. Neither of these things is conducive to a well drafted chimney pipe.
Lastly, if it's a windy day, expect to see some smoke when you open your wood stove door. Wind creates all sorts of varying pressures inside of a house and the smoke travels up and down that chimney pipe like a yo-yo if it's windy enough outside.
If anyone else has any advice or suggestions (if I'm missing anything), I'd love to read them.
Two things: I used to own a wood stove and when I would sense that I was going to get smoke in my house when I would load wood into my stove, I'd open the door just a little bit for a few seconds (probably around 10 seconds) to let some air in. I'd get the flow of air going up the chimney before I would open the door all the way. Also, an ex-boyfriend of mine once wrapped heat proof insulation around the piping that was inside and outside and that helped keep the pipe warm and the draft good inside of the pipe. That reduced the smoke that came back into the house a lot, especially on warm days.