Should I Add a Flue Damper to My Wood Stove?

[ritmatt]

I recently bought a house that included a wood stove. The house and, presumably, the stove are about 25 years old. The stove has two small intake vents on the front, but there is no damper in the flue. All of the wood stoves I've ever used have included flue dampers, which have been instrumental in slowing down the burn rate of the wood fuel and heating the stoves. Also, after burning wood in my stove once, the room it's in smelled like burnt wood for days afterwards. I think the absence of a flue damper allowed wind to blow the smell back through the not-so-airtight intake vents and into the room.

Are some stoves designed to be used without flue dampers? Is there any harm in adding one to my wood stove?

 

[murphy1244]

I recently bought a house that included a wood stove. The house and, presumably, the stove are about 25 years old. The stove has two small intake vents on the front, but there is no damper in the flue. All of the wood stoves I've ever used have included flue dampers, which have been instrumental in slowing down the burn rate of the wood fuel and heating the stoves. Also, after burning wood in my stove once, the room it's in smelled like burnt wood for days afterwards. I think the absence of a flue damper allowed wind to blow the smell back through the not-so-airtight intake vents and into the room.

Are some stoves designed to be used without flue dampers? Is there any harm in adding one to my wood stove?

Whats the make of your stove? Mine is like yours called a Old Timer and it has a fixed removeable steel flat piece and you control the burn by controling the intake air with those two vents.

 

[dave1949]

It certainly wouldn't hurt anything. The newer stoves are air tight enough to not rely on a flue damper. Every chimney/stove/house siting combination is different, so you go with what works.

Is there a reason something else in your house, forced-air heat, clothes dryer, etc. would be pulling air down the chimney? That would account for the burnt wood smell. I think creosote in the chimney or flue pipe would be be biggest contributor to that type of odor. Is that all clean?

 

[ritmatt]

Whats the make of your stove? Mine is like yours called a Old Timer and it has a fixed removeable steel flat piece and you control the burn by controling the intake air with those two vents.

I can't find any identifying marks on it anywhere, but the intake vents seem similar to yours. Two flat pieces that can be moved to block or reveal the intake vents. Here's a picture I took for Facebook a couple weeks ago.

 

[murphy1244]

I can't find any identifying marks on it anywhere, but the intake vents seem similar to yours. Two flat pieces that can be moved to block or reveal the intake vents. Here's a picture I took for Facebook a couple weeks ago.

View attachment 286851

I do not have a glass doors and my vents spin to go in or out.Wish I had glass doors but I can burn a 24 inch log.

 

[CalG]

A damper will make the air intake setting a bit less sensitive, but just something else to attend to.

We burn wood, have for over thirty years,

Downstairs stove is a Fischer that I once did fit with a flue damper. But that's gone, and all burn rate control is by way of the two screw cap air intakes on the front door.

The upstairs stove is a Vermont Castings, The air intake control is a slide lever, and it works fine over a broad range of burn rates.

If you are having trouble with fast burns on an airtight stove, check your door seals, and the fit of your flue pipes. Air can easily creep in through a poorly fitted pipe connection.

If everything is tight, closing off the the air intakes should put the fire right out.

Oh! Suggestion..if you have the fire throttled back, open the air intakes a bit before you open the door to check the fire or refuel. Get's the smoke going the right way. ;-)

 

[westcliffe01]

Look carefully for a control on the intake, there has to be one. Have the entire flue system inspected carefully. If it is that old, it is quite likely that a lot of components need to be replaced. Stovepipe does not last forever. Even good quality stovepipe may only last 5 years when used 6 months a year. I nearly burnt down a rental property when I made a fire in the fireplace and embers fell through a crack in the hearth onto the wooden ceiling below. Depending on how the flue was done, you may just be able to fit a liner, which is much cheaper than the alternatives.

 

[KennyG]

A flue damper may (on an older stove) give you some more control over burn rate, but it won't help your smoke smell. Dampers don't seal completely. Check to see if you have negative pressure in the house. Open a window very slightly and see if you get a noticeable inrush of air. The low pressure in the house will pull air in through the stove if that's the path of least resistance. You can try sealing the chimney pipe better but if it's an older stove and not an airtight one you won't be able to stop the airflow. The only thing you can to is provide another source of outside air to bring the pressure back up.

Do a search on the internet about "stack effect" to see how this works.

 

[dmccarty]

The fire is using up air to burn so air has to get into the house someway, somehow. In our case, we have a six inch pipe under the floor that pops up behind the stove to provide combustion air. In our old city house we had a fireplace. If I tried to start the fire with the clothes dryer running, the smoke would back draft out of the chimney. Only took once for that to happen. :laughing: The old city house was old enough to be leaky to air so the fire would get enough combustion air but we stopped burning the fireplace because the bedrooms were freezing when the fire was running. The air was being pulled out of those rooms and sent up to the chimney. The fireplace side of the house was comfortable though.

On our wood stove, the damper is at the bottom of the stove. I would be shocked if the stove did not have a damper. Can you find a manual for the stove on the Internet?

Later,
Dan

 

[Raspy]

A flue damper may (on an older stove) give you some more control over burn rate, but it won't help your smoke smell. Dampers don't seal completely. Check to see if you have negative pressure in the house. Open a window very slightly and see if you get a noticeable inrush of air. The low pressure in the house will pull air in through the stove if that's the path of least resistance. You can try sealing the chimney pipe better but if it's an older stove and not an airtight one you won't be able to stop the airflow. The only thing you can to is provide another source of outside air to bring the pressure back up.

Do a search on the internet about "stack effect" to see how this works.

Kenny's got it right here. Dampers don't seal completely so wind can blow back down the chimney after the fire is out and go right past the damper. Also, when the fire is going, if you damp it with the small air controllers on the front of the stove, there will be a negative pressure in the entire stove and chimney. This will help prevent smoke from entering the room. But if you use a chimney damper, the firebox can go to positive pressure and back up smoke into the room.

I like a chimney damper, but they are not always useful. Sometimes the air damper on the stove is not enough and you have to damp the chimney too. Or a sudden gust can partially be controlled with the damper if it is nearly closed.

Also, a lot of modern stoves need a high velocity draft to enter past the designed in air supply controller. This helps to keep the glass clean or to mix the incoming air with the exhaust for better combustion. The chimney damper makes this velocity lower.

Be sure you have an adequate fresh air supply! Just relying on house leakage means cold rooms and poor draft, or no draft. The best is a cold air supply from outside that is piped directly to the stove intake. It can be sealed to the stove or terminate close to the stove intake.

Finally, make sure the chimney is clear and the spark screen is not clogged. These will definitely make smoke back up into the room if blocked.