The most common complaint about a fireplace is that it is a smoking fireplace. Some smokes rolls out from the top of the fireplace and pours into the room. This not only fills the room with smoke but also stains the walls and ceiling.
This can be caused by a few things. Obviously the all the smoke is not going up the chimney, but why? The first thing to do and easiest is to make sure the chimney damper is opened all the way in the fireplace being used. If it is even slightly closed this can cause a smoking fireplace. It is like pinching a straw, not everything will be sucked up the straw. If your damper is opened all the way, make sure the chimney is cleaned and has no blockages. Sometimes the screen on the cap can become clogged by creosote.
Another possibility that the fireplace opening is too large for the size of the flue, causing a smoking fireplace. If this is the case, a fireplace smoke guard is recommended. What it basically does is it makes the fireplace opening smaller. They are available in black or brass. Also available in a 4″ of 6″ width.
If you have 2 fireplaces, sometimes what will happen, is you will be using one fireplace and smoke will come out of the other fireplace that is not being used. What is happening is that a fireplace needs air to burn and send up the chimney. It always takes air the easiest possible way. So if your home is well sealed and doesn’t have any drafts from windows or doors it may be drawing air down through the other fireplace flue and drawing some of the smoke down the chimney.
To fix this you need to make the fireplace draw air from another area. What is recommended is that the flue that is used more often is at least 4 inches higher than the other flue. You can even slightly open a window in the same room as the fireplace that is burning. This way the air is entering via the window instead of the other fireplace. You can also install a top mount damper on the flue that is not in use. These dampers make a much better seal than the throat dampers. They have rubber gaskets on them that makes a 100% seal. They completely seal off the top of the flue making it impossible for smoke to enter.
Or another easy fix is to install a Flue Extender cap. This cap can be made either to mount to the crown if there is no flue exposed or directly to any size flue. It is available in a 1′ or 2′ extension.
You can also install an outside air kit. This is much easier if the fireplace is on an exterior wall. It is basically an opening to the outside that allows air in through a door that can be opened or closed.
There may be other issues causing a smoking fireplace, what you should do is talk to a professional and see what could be causing the problem. An unlined fireplace chimney is extremely dangerous. You need a stainless steel chimney liner.