Expected BTU

[liderbug]

I keep day dreaming and sketching and thinking and...

When the garage was built it was a standard 2 car with an added 10 ft to the back. I've made some improvements, insulation etc. My shop is now a 10x25x8 box. What I'm missing in my calculations is what to expect from a hot air panel. I have a propane heater 30/40/50k, and a 1500W heater. The shop was 70 deg at 7 PM last night and is now 40 at 9 AM with an outside temp of 10 deg. I left the 1500W heater running. I'm thinking if I went to 2500/3000W the temp might hold. I say the above so you get the feeling for size (250sf) and insulation factor.

My question is: One square foot of a pop can panel will deliver ??? BTU on a average. So if I need 10K BTU and 1 sf will/would put out say 300 a 4x8 panel would work. But if only 150 BTU per foot then I'd need 2 4x8 panels. 75 would require 4 panels.

Thanks

[sunburnt]

myself ....i would not worry about the btu . buld it a big as you can. or make so you can add 1 or 2 or 4 as needs...... its free heat... and TAX free 4 now..

[brododge]

What is important is to control the heat loss from the shop. Provide lots of insulation.

I have a home built wall unit on my 16x16x9 shop. The unit is about 12x8 feet. The collector surface faces directly south and is made from discarded storm windows. The collector media is bulk furnace filter bats painted black that are hung in a cavity behind the glass. The wall behind the filter bats opens to the shop through a slot at the bottom and a slot at the top. Air naturally moves through the filter media from bottom to top because of the heat. So cool air leaves the shop at the bottom of the wall and reenters as warm air at the top of the wall.

At night to conserve heat I close the top slots to prevent air movement. If I didn't, the air flow would reverse drawing warm air from the shop ceiling and cooling it as the air moved down through the collector.

The shop is very well insulated to retain heat. It will approach 70 degrees F on a sunny 20 degree day. I do have a 1500 watt electric space heater to make sure the temperature stays over 40. It doesn't work if it is cold and cloudy. On those days I find a good book by the fireplace.

The whole thing cost me $65 plus the heater. The only maintenance needed is to take out the filter bats each fall and vacuum off the sawdust.

The vertical glass wall is under a 16 inch roof overhang and keeps cool during the summer without covering.

[sunburnt]

Wold love to see photo of you heaters .... Always looking for something different...

[brododge]

Okay

I'll put it on a new thread to get out of the BTU question.

[inetdog]

Okay

I'll put it on a new thread to get out of the BTU question.

http://www.solarpaneltalk.com/showthread.php?9499-My-shop-wall-air-heater

[liderbug]

Thanks for the advice.