Why is smoke coming into the living room?

If your chimney has been swept and your fireplace checked recently the smoking problem might be due to negative pressure.

Negative pressure of a home occurs when the air pressure in the house is lower than the air pressure outside.

When there is negative pressure inside, the outside air will enter the home through any opening it can find. Unfortunately sometimes this is through the chimney or flue.

Both mechanical and natural conditions can produce negative pressure. Modern homes are often of such tight construction that little outside air infiltration occurs.

In these homes both natural and mechanical negative pressurization can easily cause a fireplace to smoke. It will help you to consider the following examples of negative pressurization to see if they might apply to your situation.

Mechanical causes can be rangehoods, extractor fans, clothes dryers, These literally suck air out of the home.

Often the fireplace flue is the only opening available for the home to get air while one or several such appliances are operating. The result of air being sucked down the flue causes smoke to come into the home.

You can reduce the negative pressure by supplying makeup air to the fireplace or home. Sometimes something as simple as opening a window or sliding door slightly will overcome the negative pressure and cure your smoking fireplace

Natural causes include wind loading and nearby trees and high structures. If providing makeup air by opening a window make sure it is always on the side of the house that faces the wind. This will pressurize the home and should make smoke go up the chimney more easily.