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Why Is My Wood Stove Smoking?

Here are the top 6 reasons why your wood stove is smoking and not heating:

Firewood Quality:

The number one reason that wood stoves smoke and do not exhaust properly is the type and moisture content of the firewood used. If the moisture content of the firewood is above 20%, your stove is not going to perform like it should. With more than 20% moisture content, the energy created from the fire will end up boiling the moisture out of the wood. This prevents the fire from entering the second stage of combustion where a fire begins to produce heat. This heat is what drives the draft to exhaust through the stoves chimney pipe and out of the home. If you are unsure of the dryness of the wood, you should pick up a moisture meter also called a digital hydrometer from Amazon or your local hardware store.

Possible Solution:

Pick up a digital hydrometer to make sure you are using dry firewood. Try buying a bundle of firewood you know to be dry and compare how your stove operates.

Chimney Size:

All wood stoves are engineered to use the same size chimney as the inside diameter of the flue collar on the stove. If the flue collar is 6 inches in diameter, you should use a 6-inch chimney. Using a smaller sized chimney will minimize the amount of space needed to exhaust the smoke based on the size of your stove. If venting into a larger chimney pipe or masonry chimney, (per NFPA 211) you cannot use a chimney more than twice the size of the recommended chimney. A 6-inch chimney pipe is 28 square inches. If venting into an 8” round chimney pipe which is 50 square inches, your appliance should work just fine. 50 inches is less than twice the size of a 6-inch pipe. However, if venting into a masonry chimney that is 12 inches x 12 inches (144 square inches), the chimney would be too large for a proper draft. This would require your chimney to be relined which we will go over in a future article. This venting principal is true for both freestanding wood stoves as well as wood inserts installed into wood burning fireplaces.

Possible Solution:

If you are able, take some measurements to make sure your masonry chimney or pipe is properly sized. If you are unsure, have a professional out to evaluate your chimney situation if you are not sure if your wood stove chimney is not properly installed.

Chimney Type:

Freestanding wood burning stoves require black stove pipe (single wall or double wall black pipe) connecting from the stove collar and until you reach your ceiling if venting vertically or a wall if venting horizontally and then vertically. At the ceiling or wall, the black stove pipe has to convert a Class A Chimney. This can be an insulated or air-cooled pipe that is tested to UL 103 HT or a safety inspected masonry chimney. Black stove pipe cannot be used to penetrate through a wall or ceiling. Failure to follow proper safety protocols can result in a fire and most certainly a poorly functioning appliance.

Possible Solution:

Have a professional out to evaluate your chimney situation if you are not sure if your wood stove chimney is not properly installed.

Chimney Height And Wind:

The chimney exhausting your wood stove needs to be at least 2 feet taller than any part of the building within 10 feet of the chimney pipe or masonry chimney. Failure to have a tall enough chimney can cause winds to blow down the chimney at a greater force than is created by the appliance.

Possible Solution:

You can add a length of the same type of chimney pipe you have to your existing chimney to eliminate this issue. Have a professional chimney company tackle this one if you might not be capable to get on your roof.

Outside Temperature:

Hot air is lighter than cooler air and will rise due to gravity but only with the proper temperature difference. As a general rule, the temperature outside needs to be a minimum of 30 degrees cooler than indoors for a wood burning appliance to draft. For example, if its 40 degrees outside and more than 70 degrees inside, the stove should draft properly. This doesn’t mean it is impossible for a wood stove to draft, it just means you can have issues if not cold enough outdoors. It is common for service to receive an influx of calls during a warm weather front. Caps that are meant to handle higher wind situations as well as chimney draft fans are available to remedy these situations. p>

Possible Solution:

Try comparing how your stove operates on a colder day to see if this is your issue.

Negative Pressure:

Another common phenomenon that can occur in a home is when there is negative pressure in a home. This is caused when appliances like your heating system, clothes dryer, bathroom fans, recessed lighting, other exhaust vents, and even strong winds can pull air from your home. Your home needs to make up the air that has left the home and will do so through the path of least resistance. The force of draft from a stove doesn’t stand a chance against these forces.

Possible Solution:

Try turning off appliances you can like your drier, bathroom fans, recessed lighting, and any other appliance that pulls air from your home. This should reduce the negative pressure that your stove is battling. You can also eliminate this as a possibility by opening a door or window on the side of your home the wind is coming from. This will cause air to enter the home more freely and pressurize your home.

Conclusion:

There are a number of reasons why your wood stove is smoking and not heating. There can even be multiple issues happening at the same time which makes things more difficult to diagnose. Making sure your wood stove and chimney are installed properly, using dry firewood, and eliminating pressures in your home can improve the function and safety of your wood stove.