On a cold winter evening, who of us is not tempted to stoke up a fire in the fireplace, and read a book in front of the crackling hearth? You may be thinking “I am doing myself a favor by supplementing the furnace with additional heat”. But in fact, the opposite is true.
The open wood burning fireplace is a black hole of heat
I know it sounds crazy, but the air action that a wood-burning fireplace initiates in the home is wasteful. As the fire in the hearth is lit and accelerates, the combustion grabs air from your homes interior, which the furnace had already heated, and burns the combustible gasses in it. Then the fire immediately tosses the heat up the chimney. You can restrict the amount of inside air that the fireplace has access to by installing glass doors, but this will also severely limit the amount of radiant heat that fireplace can cast forward into your living space.
In the meantime the home is drawing in cold outside air from other places (i.e. windows, light sockets, doors, etc) to replace the air that is escaping the home through the chimney. This is referred to as the homes “stack effect.”
Losing heat even while dormant
Even while the fireplace is not being used, the traditional metal dampers tend to leak air since they warp and degrade rapidly in the extreme heat and corrosive soot environment. This can be corrected with a reusable chimney plug, called a Chimney Balloon fireplace damper that inflates into place in the fireplace flue to seal it off.
How to get heat out of the fireplace?
If you are serious about getting more heat from your fireplace you should have it sized for an EPA rated wood insert. Newer EPA rated inserts can run up to 85% efficient and produce significant heat for the home. But they start at $3000, so they are an investment.
There are cheaper tube construction fireplace heat exchangers with blowers, but they do not significantly increase the efficiency of the fireplace burn, so save your money.
Keep down the pollution
If you use your fireplace, burn a fast hot fire. This creates very little smoke and pollution, and it can give you a noticeable amount of radiant heat gain in the room the fireplace it is in. However, even a hot fire will not exceed the heat loss ratio of the fireplace. A slower fire is even worse since you are still losing heated air out the chimney, getting very little radiant heat in return, and generating black sooty smoke. This black type of fireplace smoke is a terrible pollutant and contributes to respiratory irritation for people with asthma and allergies.
Wood burning fireplaces are wonderful nostalgic centerpieces for many American homes. But a homeowner should be aware of the issues associated with fireplace and home heat loss.
Jason Raddenbach is an application specialist for fireplace products like the Chimney Balloon and the Smoke Pencil. With his experience and expertise in hearth products he has helped thousands of homeowners improve the efficiency of their fireplaces. Visit Jason’s fireplace troubleshooting blog.
