Hi folks. I am replacing my heat pump/air handler for a house with 2000 sq ft on the first floor and 800 sq ft on the second floor including a large loft and smaller bonus room. The house has vaulted ceilings. We were unable to adequately heat or cool the second floor with the original system (3.5 ton HP, 4 ton blower, and electric heat backup) installed in 1996 when the house was built. We live in Indianapolis, IN.
We have had seven estimates and all the proposals are for either a 3.5 ton HP or 4.0 two-stage HP with variable speed air handlers. A couple people have proposed a 5 ton blower. No one has mentioned a Manual J calculation although one person did measure the perimeter of the house after I told him several estimates were for 4.0 ton HPs. He said it was borderline between a 3.5 and 4.0 ton HP.
Here are my questions.
1. In my situation, is there much difference between the 3.5 HP and 4.0 two-stage HP? I like the idea of having a two-stage heat pump, but I do not want to oversize.
2. Should I consider zones for the house? If I decide to create two zones (for the first and second floors) with zone dampers, will it make a difference which size heat pump I purchase?
3. Is it reasonable for me to sign a contract to purchase contingent on a Manual J and/or Manual D calculation? Should I pay for the calculations? How much should they cost?