Hello.

I'm renovating a two-unit house and pursuing an Energy Star rating on the units. My HVAC guy usually applies a 'rule of thumb' so he's a nervous about the sizing numbers HVAC Calc determined. I think he's bought into the heat loss calc but he's wondering if we'll have the proper CFM for the system. As a developer I'm not an HVAC expert but I'd like to start paying more attention to doing it right.

Anyhow, I'd like some expert opinion to these to see if these numbers seem reasonable, specifically the blower sizing.

Unit One (1st fl) is approx. 900 sq ft. Heat gain is calculated at about 14k BTUH, Heat Loss about 30k. For reasonable a margin of safety, I anticipate using a 1.5 ton AC with a 40k BTUH gas forced air furnace. My HVAC guy is assuming a 800 CFM blower for this unit.

Unit Two (2nd & 3rd fl) is approx. 1700 sq. ft. Heat gain: 22k, Loss: 37K. Equipment sizing: 2.0 ton and 60k BTUH furnace. My HVAC guys is assuming a 1200 CFM blower for this unit.

Question: Do you anticipate any problems with the blower sizing for these units, specifically since my heating needs are much greater than my cooling needs?

Thanks in advance for your help and opinions.