Q: I am tired of high propane prices and I can’t afford to upgrade my furnace yet. So, this winter I am trying to heat my living room area with my wood burning fireplace. My intent is to use the fireplace as a supplementary heating source so my furnace doesn’t run so much. SB

[SB has an open zero clearance fireplace that is built on an outside wall of your home. It has no glass doors and not heatilator or fan.]

A: SB, Unfortunately, Efficiency wise this is probably the worst type of setup possible in order to generate heat to the living area. As a matter of fact, you will probably find that you consume 10% to 230% more propane when you are using the fireplace than when you don’t use the fireplace. I would encourage you NOT to use your fireplace as a way to save money on heat. Here is why:

1) The first thing you do when you go to start a fire in the fireplace is open the damper in the flue. Opening your fireplace damper is like opening a hole in your sealing. The second you open it the warm interior air is raising right out the chimney. So until you get a sizable fire going that is generating a good amount of radiant heat you are loosing heat to the chimney.

2) While you have a sizable fire going in the fireplace you are loosing in 3 ways.

  • The fire is drawing warm air from your home for the combustion process.
  • The fire is casting 90% of its BTUs up the chimney and only putting forward 10% into your home as usable radiant heat.
  • The chimney is continuing to pull warm atmospheric air from your home and allow it to rise out the chimney. This in turn creates a vacuum stack effect that draws cold outside air in through cracks, windows and doors making your home cooler.

3) When the fire dies down and smolders you still have to wait with your damper open. The smoking and heat has to stop entirely before you can close the damper. During this time your fireplace is not generating any radiant heat at all and the damper is still robbing your home of heat.

SB, The moral of this story is a fireplace is not a good source of heat for a home. I know that our forefathers use to heat their entire homes with this type of heat, but the issues that I explained is the reason that potbelly stoves and wood furnaces became so popular in the 1800’s.

There are some things you can do to make your fireplace more efficient and I discuss them in this blog article: http://chimneyballoon.typepad.com/blog/2007/01/how_can_i_help_.html