There can be several reasons why a fireplace smokes. The most important thing to remember is to try and notice the different conditions that are present (weather, wind, size of fire, is the heat on or dryer running) when it is smoking so the problem can be proper diagnosed.

Smoking patterns seen just above the fireplace opening can indicate a problem

Check to make sure the damper is fully open before each fire.

This is a very common problem and occurs several times a year. Some homeowners simply forget to open the damper. The smoke comes back into the room since the opening to the chimney is partially blocked or closed completely.

If this occurs attempt to open the damper quickly. Do not attempt to open the damper if flames are visible and high enough to come in contact with clothing. Call the fire department immediately and they will handle the situation. Then close the doors and open windows to that room and get everyone out of the house.

It smokes when the fire is first started.

If smoke just doesn't seem to want to go up the chimney or if smoke suddenly comes back into the room when you light the fire it may be cold draft problem.

When you first light the fire, wood is on the grate, and very little flames showing chances are that the chimney just has not had time to warm up or start a draft. The result may be that some of the smoke goes up the chimney and some back into the room. In the worst case there may be a cold down draft or a "cold air plug" in the chimney that will not allow any of the smoke to go up the chimney until the flue has warmed up enough to start a draft.

To help with this problem, especially if it has occurred before, it is best to warm the flue before you put wood on the grate. This gives the draft a chance to get started and help get rid of the cold down draft or "cold air plug" in the flue. The best way, if available, is to let the gas starter burn for about 10 minutes before you turn it down and place the wood on the grate. Warming up the system before the fire gets going also increases performance. If you do not have a gas starter the starter logs work well by just letting them burn for about 10 minutes before wood is placed on the grate. It is not a good idea to use newspaper to warm the flue. It can be dangerous or even start a chimney fire if direct flames contact is made with the soot build up.

It smokes after the fire has been burning a while.

If the fireplace smokes after it has been burning for a while this may be a true draft problem with the chimney or flue system. Several causes could be suspected such as a larger fireplace opening that the flue size will handle or an air turbulence problem at the chimney termination point. A chimney inspection will need to be done in order to solve this problem.

I have to open a door to stop the smoking.

In the newer airtight homes opening a door may stop a fireplace from smoking. If this is the situation notice what appliances in your home is may be operating at the time the fireplace is smoking. This can occur after the fire has been burning a while. Appliances such as the vent hood over the stove, bathroom vent fans, and dryer or if the heat is on and the air return is working could be the source.

If this is the case you may have a negative pressure problem in your home. A fireplace is a natural draft system and it cannot compete with air being used by mechanical devices.

If the fireplace is smoking and these appliances are running start shutting them off until the fireplace stops smoking and the problem should be solved.