I think we've decided to put the wood stove in the basement. If you have the chimney/flue running up two stories and insulate it with Kaowool, would that stop the backdraft potential or negative pressure issues?
Woodstove in basement-backdraft issues?
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Welcome to the forum Ravenly.
I do not think it would necessarily do away with the negative pressure issue. For sure, many folks have the stove in a basement. For some it works, for many it turns out to be a big pain.
Is your basement insulated? If you want a wood stove in the basement it has to be insulated else almost all the heat from the stove is soaked up with the cement or blocks and you get no benefit.
I do not think it would necessarily do away with the negative pressure issue. For sure, many folks have the stove in a basement. For some it works, for many it turns out to be a big pain.
Is your basement insulated? If you want a wood stove in the basement it has to be insulated else almost all the heat from the stove is soaked up with the cement or blocks and you get no benefit.
I recently installed a wood stove in my finished basement. It is all insulated with R-9 and potentially an unfortunate situation, the suspended ceiling has decent insulating properties. I was concerned with negative pressure because I have enough to pull a the basement door closed at the top of the stairs if it is within 6 inches of closing.
The install ended with a 32' chimney which provides great draft. In the end, only on an occasional start up will I get smoke in the house. Outside of that it seems to be operating well.
The install ended with a 32' chimney which provides great draft. In the end, only on an occasional start up will I get smoke in the house. Outside of that it seems to be operating well.
I also have a basement installation. Single story ranch. Basement is unfinished/uninsulated. Stove is connected to internal block and tile 7x11 chimney. Drafts great, no smoke issues. We moved in last year and burned last winter. A couple weeks ago I finally ripped down all the fiberglass insulation from the floor joists (along with 4 dead mice and a 1/2 gallon of mouse poo) and now the 1st floor gets more than enough heat.
My stove is in my basement workshop, exhausting through a 30 foot 6 inch uninsulated liner in an external masonry chimney. There was no room for insulation in the old masonry flue so I went without it. If anything, at times I have too much draft, I assume because of the length/height of the chimney. The stove has never backdrafted, not once.
You'll find folks here with insulation and without, though not sure how many have crossed-over from one to the other to make a comparison.
But to answer the OP's question, insulating the liner will not eliminate a potential for backdraft, which would occur upon lighting the stove, when the flue is cold. Insulation won't create heat, so if you have positive (downward) pressure in the flue, insulation won't remove it, unless you are planning to only let the stove/flue cool for a couple of hours at most between burning in it. In that case, you could go longer between burns with an insulated liver versus an uninsulated liner.
As far as I can see, the only advantage of an insulated liner is the development of a strong draft faster than in an uninsulated liner. I'm not sure if that's really much of a need for most folks.
Insulation to protect the surrounding structure from the heat of the flue is a different story.
You'll find folks here with insulation and without, though not sure how many have crossed-over from one to the other to make a comparison.
But to answer the OP's question, insulating the liner will not eliminate a potential for backdraft, which would occur upon lighting the stove, when the flue is cold. Insulation won't create heat, so if you have positive (downward) pressure in the flue, insulation won't remove it, unless you are planning to only let the stove/flue cool for a couple of hours at most between burning in it. In that case, you could go longer between burns with an insulated liver versus an uninsulated liner.
As far as I can see, the only advantage of an insulated liner is the development of a strong draft faster than in an uninsulated liner. I'm not sure if that's really much of a need for most folks.
Insulation to protect the surrounding structure from the heat of the flue is a different story.
Ravenly said:
There are more factors than just the location of the chimney that will affect draw. We would just be speculating on how the chimney will react in this circumstance. Are you proposing lining an existing chimney? Is it interior or exterior, how tall? It's important to determine if there are already several devices and appliances creating negative pressure in the area. Typically these would include a furnace or boiler, gas hw heater, dryer, bathroom exhaust fan, etc.
If this is an interior 2-3 story flue and there are minimum competing appliances, the flue may draw strongly. If this is a 1.5 story flue, exterior and there are other appliances competing for air in a fairly well sealed space, weak draft or negative draft could be an issue. But if this is the case, there are possible remedies.
Thanks so much for all of the replies 
Hubby and I both work for commercial/industrial insulation companies so we can get Kaowool either free or dirt cheap.
The chimney will be run inside on an exterior wall, through two stories and an attic (not in anyway affiliated with the furnace chimney). The dryer and whatnot are located on the first floor. In the basement (910 sq ft), in a separate room we have the furnace and water heater.
DH wants to cut vents in the return air ducts to draw air up, I am not sure how this affects the balance of airflow of the house.
Hubby and I both work for commercial/industrial insulation companies so we can get Kaowool either free or dirt cheap.
The chimney will be run inside on an exterior wall, through two stories and an attic (not in anyway affiliated with the furnace chimney). The dryer and whatnot are located on the first floor. In the basement (910 sq ft), in a separate room we have the furnace and water heater.
DH wants to cut vents in the return air ducts to draw air up, I am not sure how this affects the balance of airflow of the house.
Ravenly said:Thanks so much for all of the replies
Hubby and I both work for commercial/industrial insulation companies so we can get Kaowool either free or dirt cheap.
The chimney will be run inside on an exterior wall, through two stories and an attic (not in anyway affiliated with the furnace chimney). The dryer and whatnot are located on the first floor. In the basement (910 sq ft), in a separate room we have the furnace and water heater.
DH wants to cut vents in the return air ducts to draw air up, I am not sure how this affects the balance of airflow of the house.
Many here will chime in about this. Cutting holes in the vents or the floor I believe violates fire codes, as it would allow fire/smoke to spread much faster from downstairs to upstairs.
Is the basement space one that needs to be heated? If not, it is far better and more efficient to put the heat (the stove) where it is needed.
If it has to go in the basement, with the intent of heating upstairs, expect the basement to get quite hot in comparison with upstairs. If there is a nearby staircase, that may help a bit.
Also, is this a new flue? If so, I would install a metal flue, in which case the insulation question is moot.
If it has to go in the basement, with the intent of heating upstairs, expect the basement to get quite hot in comparison with upstairs. If there is a nearby staircase, that may help a bit.
Also, is this a new flue? If so, I would install a metal flue, in which case the insulation question is moot.
Do a google search for 'stack effect' and you'll see the best place for a wood stove is at or above the neutral pressure line, which simply is not in the basement of most homes.
Unfortunately the basement is the only place that is feasible to do due to our floor plan and placement of windows. We plan on turning the basement into a rec room/playroom and spending lots of time down there. Getting the heat upstairs is somewhat secondary. We want to have something in place in case natty gas gets to be crazy expensive. (We are big into studying the economy and are VERY VERY concerned about the massive amounts of printing going on at the Fed and what impact it may have on gas prices). If we had to, we'd just make the basement our place to hang in the winter. However, if there are going to be safety concerns I'm not sure.
My other concern is the fact that our house is two stories, so its going to have quite a long chimney. Not sure how this affects the backdraft. I did the basement door pressure test (Thanks for that, btw! I found watching that door rather fascinating!). Pressure was equalized without the furnace running. With the furnace running there was some noticeable pull on the door. Not enough to close it, but I could actually feel the pressure on the door.
My other concern is the fact that our house is two stories, so its going to have quite a long chimney. Not sure how this affects the backdraft. I did the basement door pressure test (Thanks for that, btw! I found watching that door rather fascinating!). Pressure was equalized without the furnace running. With the furnace running there was some noticeable pull on the door. Not enough to close it, but I could actually feel the pressure on the door.
With a tall interior stack it is possible that you are going to have to damper the flue due to too strong draft. This might be helped with downsizing the flue a little, but we need specifics on the stove and the chimney design first. If the furnace is the only competition, either the stove or the furnace could get an outside air kit. More important are going to be the stove size, location, safety, chimney design.
dave11 said:Ravenly said:Thanks so much for all of the replies
Hubby and I both work for commercial/industrial insulation companies so we can get Kaowool either free or dirt cheap.
The chimney will be run inside on an exterior wall, through two stories and an attic (not in anyway affiliated with the furnace chimney). The dryer and whatnot are located on the first floor. In the basement (910 sq ft), in a separate room we have the furnace and water heater.
DH wants to cut vents in the return air ducts to draw air up, I am not sure how this affects the balance of airflow of the house.
Many here will chime in about this. Cutting holes in the vents or the floor I believe violates fire codes, as it would allow fire/smoke to spread much faster from downstairs to upstairs.
Violaton of codes all depends on local ordinances, many, many, many, homes in my area, NEPA, that have wood stoves and multi story homes have vents in floor/ceiling including my home. Violation of code? Not that I know of. Some areas have different requirements, like vents with a circuit that when broken (the circuit essentially melts) the vents automatically close. Note this is not required in my area. Check with local codes to see what if anything is required.
Also please note that vents in floor/ceiling do NOT draw heat up, they act as a cold air return in most homes, usually the heat is drawn up a stairwell. The warm air acts similar to electricity and takes the path of least resistance, in my case up the stairwell, and the vents allow the cooler air to fall into the stove room.
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