Heating, Air Conditioning, Fridge, HVAC/Cold Air Return


I have a down flow furnace that is 64,000BTU's. How big does the opening for a cold air return need to be for it?

You should have at least 200 square inches of free area at the smallest area that the air passes through from the living space to the blower compartment.
Return air grills and filters reduce the area 50%.
examine the return air passage, find the smallest area that the air passes through between start to blower cabinet and that's the amount of free area the return has.
As the air filter collects dirt the free area reduces more then 50%.

Heating, Air Conditioning, Fridge, HVAC

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Jim Barnhart


Fifty + years conditioning the air.


Answer questions about , residential and commercial. Answer questions about sheet metal fabrication. Fifty years plus experience. No answers for oil equipment, No answers for kitchen appliances, No answers for laundry appliances, I don't specialize in one particular area of the HVAC area, I'm more of a General Practitioner, Limited in refrigeration/

Hands on since 1950

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