Inverted air creates downward pressure directing smoke and fire gases towards the inside of a home, which is a threatening situation for the owner. The downdraft may release carbon monoxide, a fatal gas to the residents. Invested chimneys require immediate attention.
A fireplace should have a good air circulation opening to run correctly. Some inverted air is the result of external obstructions that interfere or block the movement of air around the fireplace. A large tree near the unit, for example, can cause poor air circulation, resulting in the downdraft in the chimney. Also, nearby buildings may interfere with the airflow in the vicinity of the fire. Increasing the height of the upper part often solves the problem, as the tall chimneys have better air currents that low.
A house develops negative pressure when the air is sent abroad exceeds the amount entering. The negative pressure, a major cause of the downdraft, often occurs when some appliances, such as range hoods, expel air from the house. Avoid turning the hoods on when the wood-burning fireplace is lit. You can also alleviate the negative pressure by opening windows to allow air intake.
Light the fire
Households and fireplaces operate on the basis that hot air rises. The heat creates an updraft, expelling the smoke through the unit and out of the house. When you first turn on the fire, it has not created enough heat to achieve an immediate upstream, causing a downdraft. Using newspapers or additional wood to create an intense fire to initially light it can help solve the problem, as explained by the magazine “Extreme How-To”.
Strong wind can affect the ability of the chimney to maintain an effective updraft. The design of the top of the fireplace can also cause problems in the drafts. Special covers, however, can harness the wind to eliminate downdraft. These caps are comprised of two bells that guide the wind around the unit. As the wind blows around the top, an updraft is created, which expels smoke and gases out of the chimney.