Fan for use in metal ducts around fireplace... (my fireplace, cost, warm)

[Tilt11]

My fireplace has a metal duct inside the wall with two vents above the fireplace, two below. I want to put in a fan in either the tops or bottoms that will help push the warm air out a bit when I have a good fire going.

Im not sure what strength of fan I should go with. Something like THIS which is 105 cfm, or perhaps one that with a little less air flow. I dont want it to be too much where it would essentially cool the warm air but just enough to move it out a bit better to make it more efficient.

[thecoalman]

Looks like this:





That's actually the fireplace we have prior to renovation ,the wallpaper was the first thing to go. The ducts work fantastic on their own. I know on ours the top grate gets hot enough it's uncomfortable to hold your hand on it.

The way these work is there is cavity behind the fireplace, the air is naturally pulled through the bottom grate and circulated through the cavity warming the air and it's expelled out the top. If you do put a fan in either push the air into the bottom grate or blow it out of the top grate.

[K'ledgeBldr]

Convection works just fine without assistance. Besides, the "so-called additional heat" you think you're getting probably doesn't cost as much as the electricity you're using to run the fan(s).