Any way to add more surface area to the air box?

[hans747]

Hi everyone!

Okay, my last big question for the day:

Last season, i added a gas log DV fireplace to my basement office. The unit is an older Lennox fireplace that a friend sold to me for cheap (He's a homebuilder, and this unit had been sitting in his storage unit for a few years). Anyway, I'm starting to see the limitations to this older fireplace and the cheap-o fan that I got from Amazon.

First things first, I'm getting a new fan pretty soon.

Next, I was wondering if there is any common way to safely add more surface area to the air box? I was thinking that I could install vertical strips of metal (held in place with magnets) along the top of the firebox to increase the transfer of heat.

Has anyone tried this? Are there dangers involved? Are ther any off-the-shelf systems for getting more of the heat out of a DV fireplace?

 

[DAKSY]

What is the BTU rating of the fireplace &
what is the square footage of your office?
Are the walls insulated? Does is have an
uncovered concrete floor?

 

[hans747]

Good questions... I had to go back and do some homework.

20,000 btu
700-800 square feet
Insulated exterior walls
About 50% of the floor has rugs. The rest is bare.
9-foot ceilings
Staircase to upper floor has a closed door

 

[DAKSY]

20K BTU is INPUT. If the efficiency is 75% you'll get 15K OUTPUT.
If your insulation is average R13 walls, you will be able to heat about
375 square feet MAX with that unit, no matter WHAT you do to it.
You either need a bigger unit or you need to cut the sf about in half.

 

[hans747]

Thanks for the math, Daksy. Very helpful stuff. It was a few years since I did the insulation, but I think it was somethign like R19 or 21. Still, not huge difference there.

I am closing off the rooms that I don't use, and thinking about ways to close off the staircase. I might also start bringing in some more rugs to cover more of the bare concrete.

I spent some time crawling around, and i noticed that the fan (FBK-100 by Fireplace Blowers) had moved forward a few inches moved inside the airbox. Apparently i did a quick job of installing it last year. It was basically blowing most of its air right into the bottom of the fireplace.