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# adding heating and air duct to converted garage

## adding heating and air duct to converted garage

#1
10-07-10, 07:12 AM
Member
Join Date: Oct 2010
Location: usa
Posts: 1
adding heating and air duct to converted garage

What size (airflow) do i need for this 11 x 13 room

#2
10-07-10, 12:58 PM
Member
Join Date: Mar 2006
Location: Wet side of Washington state.
Posts: 16,321
You first need to do a heat loss / heat gain calculation on the room.

#3
10-07-10, 02:24 PM
Member
Join Date: Jul 2004
Posts: 1,694
First you must determine the BTU/hr and a rough rule of thumb to get this is to allow 10 to 20 BTU/hr per sq.ft of floor area.

In your case 11’x13’ = 143 sq.ft of floor area, say 150 sq.ft times 10 = 1,500 BTU/hr

To find now the air flow in CFM (cubic feet per minute) you need the temperature rise. Lets assume the room is to be maintained at 70 F and your heated air is at 100 F. The temperature rise is then 30 F

Then, CFM = BTU / (1.08 * TR) or 1500 / (1.08 * 30) = 46 CFM, say 50 CFM

You substitute your actual conditions to the above to get a more accurate result