I have recently hired a heating company to design and install a new gas furnace and ducting. I'm not sure they really know what they're doing. I have an 1800sf house in a cold climate (Vermont). They are installing a new furnace with 70,000 BTU output and max CFM of 1300 with the blower on high.
I have two questions.
1.) Does this furnace have enough CFMs? I've read that a general rule is 1 CFM per sq. ft. Is that correct?
2.) Shouldn't the total CFM of the supply ducts add up to the max CFM of the furnace?
Any advice would be greatly appreciated. Thanks in advance!