Some homeowners want to know whether installing a coal stove in an existing fireplace is possible. The answer is yes. However, proper flue diameter, hearth size, chimney type, stove heating output, fireplace opening size, and room ventilation are necessary.

Flue Size and Chimney Type

It is only possible to fit the coal burner into a fireplace when it is a class one chimney. If you plan to replace the gas fire, ensure you don’t have a pre-cast flue or class two chimney since these are incompatible with coal stoves. Afterward, you’ll want to review the fireplace flue diameter. The coal burner must be attached to the proper flue liner or flue size; otherwise, it will perform poorly and even become hazardous.

Most stoves up to 70,000 BTU/hr require a minimum six-inch flue diameter. Suppose you find that the fireplace chimney has a smaller size compared to the flue diameter which is required for the stove. In that case, it probably isn’t safe to attempt installing one. You’ll also need to watch for cracks because you must repair these even if you plan to install the flue liner. Suppose the existing chimney isn’t suitable for stove installation. In that case, it might be possible to get around this by installing the twin wall flue. 

Combustible Distance

Another factor that you must take into consideration is combustible distance. When fitting the coal stove into the existing fireplace, you must ensure the fireplace opening is large enough to provide adequate clearance from combustibles. It shouldn’t be too close to materials such as wallpaper or plasterboard to prevent them from catching on fire. The exact distance will vary from one stove to another, so it is best to consult your manual before installing it. 

Suppose your fireplace is constructed primarily from stone, brick, or other non-combustible materials. In that case, most jurisdictions have no specific regulations regarding distance. However, your stove’s performance could be adversely affected if you don’t provide sufficient heat and air circulation space. 

Stove Heating Output 

Generally speaking, stoves have much greater efficiency than fireplaces regarding outputting heat. The increased output means you may only need a small stove. One that may not fill the entire opening. An online stove calculator is the best way to determine which heat output works best for your room/house, so it doesn’t get too hot. If your stove is oversized, your fire may always smolder and create issues. Also, if your stove is undersized, you may shorten the life of the stove by constantly overfiring it. 


Stoves require air for their operation. Suppose you position them in a space without adequate ventilation. In that case, you might experience various issues, such as smoke not rising from the chimney or problems starting fires. Therefore, coal burners positioned in existing fireplaces must have access to high air permeability, which might require a ventilation brick.

You will need to run a pipe from the fireplace insert up in the chimney roughly a third to half the way up the chimney. Most installers use a flexible flue pipe. If your chimney is larger than the flue pipe, you will need to block off or insulate the chimney to prevent your warm room air from getting sucked up the chimney. Some fireplace inserts come with shrouds to block off the fireplace opening.