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#20092 01/08/03 09:50 PM
Joined: Mar 2002
Posts: 179
D
derater Offline OP
Member
Just did a small 'in-laws addition and likely went a bit heavy on the feeds.Is there a simple sq. ft./amp.Btw,per the builders layout.thanks.

#20093 01/08/03 10:06 PM
Joined: Oct 2001
Posts: 41
R
Member
My formula was, I guess still is even though I don’t do much residential anymore as follows:

Square footage of room times 8 for new construction or a tight house.

Square footage of room times 10 for an older / drafty house

It seemed to work fine I would fudge it depending on the room as well maybe a little more for the bathroom a little less for the bedroom.

#20094 01/08/03 10:07 PM
Joined: Oct 2001
Posts: 41
R
Member
Oh yeah forgot one important thing that’s the wattage!!

#20095 01/08/03 10:22 PM
Joined: Nov 2002
Posts: 267
W
Member
That's a good method, also you can go by the cubic foot, which makes for ceiling heights, some ceilings are pretty high. 2 watts per cu.ft.

#20096 01/09/03 12:24 AM
Joined: Aug 2002
Posts: 141
E
Member
In years past we installed 10 watts per sq ft. With new energy requirements (attic insullation, double pane windows, etc, allow us to install only 3 watts per sq ft. I've never known an inspector to check the wattage of installed heaters. When in doubt I install on the high side of 3W/sq.ft. I believe the inspectors allow a maximum of 3,ooo watts installed on a 20 amp 240 volt circuit.Here in Seattle it does not get below 30 degrees too often. bob


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