There are 2 fireplaces sharing one pit, 1 on each side in 2 separate rooms. Will burning wood most of the night help with heating costs? What are other methods for cutting back on heating?
Bob L has it right. The amount of air sucked up the chimney will be far greater than any heat gain without glass enclosures. Enclosures also allow control of the rate of burn, resulting in firewood lasting several times longer than uncontrolled burn. You can also get blowers that will blow heated air from the fireplace into the home. Under these conditions, you may be able to heat the entire level of the house with little help from your heating system.
Heating a home with wood is really nice. To cut back on heating put up plastic over your windows, use a blanket to cover the bottom of your doors to stop air leaks, fill any cracks where outside air can come in with poly fill or expanding foam insulation. Check your attic to make sure there is adequate insulation. Have your chimney inspected to make sure it is up to code, and cleaned properly. The wood should be dried at least a year be for being burned, and hardwood burns longer and there is less creosote.
I read they're not effective because cold air can come inside the chimney while the flume is open and you're burning wood. I'm sure as long as you have logs lit it's better than nothing. I don't think you could only get by with a fireplace though. You may want to supplement space heaters along with the fireplaces.
A fireplace that doesn't have an independent outside air source actually increases you heating bill if you leave you furnace on while using the fireplace. If you turn the furnace off then you may experience portions of the house that are cold.- Why? The wood needs air to burn. It takes the air from the inside the house unless you have a separate air source piped to the fireplace. That air is then replaced by outside air some of which will be heated by the furnace if it is on. Otherwise, some portion of the house will get colder. Even a hot fire place and chimney that is open after the fire is out can draft sufficient air up the chimney to replace the air in your house up to 5 times in one hour. I know this doesn't seem reasonable but if you do a carefully engineering analysis, you will see it is true.
Wood is a very effective means of heating. Make sure your chimney is clean and in good repair first. Be sure you have a good damper to control the burn. A closed, insert type, fire place with a blower or heat exchanger is best. The wood needs to be dry and seasoned and of a good BTU producing variety. You can find all this info on line, Your State extension office site is a great place to look. Also, please remember burning wood puts the same pollutants in the air as wood that is just laying on the ground rotting, so why not put it to good use. Most people bank their fire at night, if you intend to have it burning all night you will have to get up every few hours and tend to it. This is what I do: I have a mattress heating pad on the beds, turn this on an hour before you plan to go to bed. Bank your fire before you retire for the night. Set the furnace on 55 or 60 and it will turn on after the fire stops putting out heat. Get up in the morning a little before the rest of the family and stir the coals a bit and put on some more wood and in no time it will be warm again. You can set a kettle of water on top to put moisture in your air. Long ago, when I had a freestanding iron stove, I would put a full large whistling tea kettle on a high trivit on top of my stove as a fire alarm in case my fire got too hot. You could try this and load, not bank your fire before bed I would sit up with the fire the first few times though. Good luck!.
