Specialty caps and cap dampers can solve back puffing problems. As the weather gets colder and we close up our homes, turn on the furnace and use our fireplaces, we sometimes experience smoke coming back into the room. Why does this happen?
The underlying cause of back puffing is negative pressure. When your home is closed up your appliances that vent to the outside (like you furnace, your clothes dryer and your fireplace or woodstove) take air from the inside and “push” it to the outside. If your home is air tight, the largest, least pressurized opening will be the one that will be used to bring outside combustion air into the home to attempt to equalize the pressure. Your furnace normally has a draft assist fan and your dryer motor creating more pressure to vent out than your fireplace or woodstove opening. To fix this issue you need to get more outside combustion air. Opening a door or window an inch or two will normally fix the problem.
Occassionally, low barometric pressure or wind can also cause smoke to back up into the room. Opening a door or window an inch or two may not solve this problem! Wind problems can be addressed with special high wind caps. But low barometric pressure may cause you to have to wait to start a fire. We always recommend that starting your fireplace or woodstove be done with kindling and fire starter or paper. Start small and HOT. Make sure there is draw before you add wood. That way if there is a problem it will be very easy to put out.
Another problem happens with double fireplaces, specifically upstairs and one in the basement. What causes the smoke to enter the level where the fireplace is not being used? The most common reason is the damper on the unused fireplace does not seal completely. This can be resolved by installing a new, top closing damper assembly. This fix is not inexpensive, but it resolves the issue.
In extreme cases where there are structural issues with flue size or height cannot be corrected, there is a fix. Expensive, but the manufacturer gives a 6 month money back guarantee that the top mounted, sealed bearing Exhauston fan will solve the problem.
Give us a call if you have additional questions. Have a safe and warm winter