Registers per square footage?

Old 02-05-02, 07:58 PM
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What is formula for heat registers per square foot?

I am putting two new rooms in my cellar. I have gas heat, forced hot water. I will be putting a new heating zone in these two rooms. How to I know how may feet of baseboard heat I need in each of these rooms? One room is 350 sq ft, the other is 154 square feet. Thanks.
Old 02-05-02, 10:05 PM
Join Date: Mar 2000
Location: Lake Murray, SC USA
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There is a lot of information missing from your post, but I will make some assumptions to get you "in the ballpark".

I am assuming you have no windows, therefore no heat loss by infiltration or thru the windows. Therefore, you have 3 ways you lose heat, thru walls, floor, and ceiling.

Assuming a bare concrete floor 6" thick, the heat loss coefficient is 0.59 BTU/hr-ft2. So for the big room it is 207 BTU/HR, and for the small room it is 91 BTU/HR.

You did not provide the room dimensions, so I am assuming they are square, therefore the big room has 18.7 ft walls (assume 8 foot tall) and I also assume 8" cinder block with 3/8" drywall, for a heat loss coefficient of 0.28 BTU/HR-FT2. Therefore the heat loss thru the walls for the big room is 168 BTU/HR and for the small room is 112 BTU/HR.

Assuming the ceiling is uninsulated, the heat loss coefficient is 0.16 BTU/HR-FT2, so the ceiling heat loss for the big room is 56 BTU/HR, and for the small room is 25 BTU/HR.

Adding up the total heat loss for each room yields, 431 BTU/HR for the big room, and 228 BTU/HR for the small room.

Now, review the heat rating of the baseboard heating your are considering (it will be rated in BTU/HR/ Foot of baseboard). Divide the figures above, by the baseboard heat rating, and it will tell you the number of lineal feet required. BE SURE TO PLACE BAEBOARD ON OUTSIDE WALLS ONLY, NOT INTERIOR WALLS, IF POSSIBLE.

Sorry I could not provide an exact number of feet of baseboard required, but there are many variables to consider, and it is an engineering calculation, based on materials of construction, and exact dimensions, not just square footage.

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