Is there a SAFE way to add outside air to an existing fireplace.
Our home has a brick lined conventional wood burning fireplace, with an ash dump in the floor beneath the grate. This ash dump is accessible in the crawlspce underneath.
Can I convert this ash dump to a fresh air intake by running steel duct to the outside?
Thanks Scott
Replies
How tight is your house? I have read that most chimneys do not benefit appreciably from adding outside combustion air. (lopez labs did the research iirc) If you have a sips, ICF or similarly "tight" house it may be necessary.
If you do, I would place some type of fireproof shroud over the ash dump to be CERTAIN no embers fall in, and be sure to run the intake to the windward side of the house. I'd put a damper on it, at the firebox, as well. 4" metal duct should be plenty for most fireplaces.
Does your fireplace have a door? A lot of woodstoves use an "air wash" of cool air to keep smoke off the door and keep the glass clean - with a little work, you could have the air enter up there where there is less chance of hot stuff falling in.
I once put a set of steel tubes in the back of my fireplace and circulated outside air thru them into the room. That over-pressured the house, lending more air than was being sucked up the chimney. This was a metal set-in fireplace with brick front and we used a glass cover with adjustable vent holes.
The air coming out the duct above the fireplace opening made the wife's cooking thermometer go off scale (>500°). The fan came on automatically with a 200° klix-on switch. The duct and lines were well insulated.
The only problem was that I had to then get a house humidifier.
When the fan came on, you could feel the air around all the windows instantly reverse direction.
But, 3 years later we had to guit using the fireplace cause of my daughters asthma. It definitely reduced our heating bill while we were using it since the firewood was free.
PlaneWood by Mike_in_Katy (maker of fine sawdust!)
PlaneWood
Doing that to mine now. Local code here won't let you use the ash dump. Has to come in from the side, short duct to the outside wall.
Is there anything wrong with boring a couple holes straight through the back of my brick fire box and the outside brick? Then installing a couple of pipes through the holes and put screens and a weather hood on the outside ends. I'm thinking three or four 1.5" holes, maybe four to six inches off the floor of the hearth. I'd have to figure out some type of shut-off.