Lightning wrote:How do I figure out how much heat I'm getting from my furnace? Lets say my cold air return is 67 degrees and my warm air duct is 107 degrees. Lets also say my blowers are pushing 1000 cubic feet per minute. What is the net output in BTUs per hour?
The simplified formula for air is - BTUH = CFM x 1.08 x delta T (deg F)
1000 cfm x 1.08 x 107-67 = 43,200 btuh.
Word of caution. You need to know the actual air flow not just the "rated" air flow. Fans ride on a curve against static pressure resistance just like a pump rides against system friction loss. You need test instruments and some knowledge/training to read actual air flows.