Will my small HVAC [heat pump] move enough air?
Hey guys, I’m completing a new build in Chattanooga, TN. (South end of CZ 4) Using coolcalc and getting as detailed as I can I’ve come up with a sensible load of 28,000. 2300 sq ft single level. Should be pretty tight. R20 walls and R45 sealed roof assembly with continuous polyiso on both. My HVAC guy predictably shot down my suggestion of a 2 or 2.5 ton heat pump and wants to install a 4 ton. His reasoning has nothing to do with the load calc. I have high ceilings. A lot of the house ranges from 10-14 feet. He argues that a smaller unit won’t move enough air to comfortably cool the house. All of my ductwork will be in the basement underneath with ducts coming up through the floor. I’ll have an ERV with its own duct system.
I’m specifically wondering about the logic of using a much larger Hvac system just to move air around. Is that true? Everything I’m reading on this site is pushing toward 1000 or even 1500 SQ per ton. How much does air volume affect that (due to high ceilings) in the real world?
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