I am a homeowner trying to sort out the hvac issues in our home - have had a few contractors out to look and want to vet some recommendations and questions.
Home is from 1986, new england, about 2200sq ft downstairs and 1200 upstairs - loft ceilings everywhere. 5 year old Carrier infinity ECM furnace and 5 ton 14 seer compressor. upstairs is offset from downstairs and farthest bedroom might be one story up and 80 feet away from the air handler. Hardly any airflow there.
In Summer, AC needs to run for hours to cool from 78 down to 72; maybe one degree an hour and that is downstairs, upstairs is hot, maybe 4-8 degrees above downstairs depending on room. In winter, heat downstairs is good, but upstairs ranges 2-4 degrees cooler than downstairs, but heat situation is definitely better than cool. House is well insulated.
Contractor did measurement and when system called for 2000CFM, measured 1200 CFM with 0.5 static; he then found some foam insulation in the blower and system went up to 1700CFM, 0.8 static (limit of blower - not running efficently). He suggests no more than 3 tons downstairs due to ductwork sizing.
Computer model he ran says 6.1tons for house with about 4 downstairs and 2 upstairs; but given the way model works and some high foyer areas that retain heat, suggests 3 ton downstairs and 2.5 ton upstairs (is this slightly undersized based on computer model? Is such ok?).
So, recommendation is downsize (rebates for this) downstairs unit to 3 tons.
Install heat pump and new ductwork upstairs at 2.5 tons.
Does this all sound reasonable?
Other contractors had similar suggestions, but were not as scientific about it all.
Lastly, any thoughts on exposed spiral ductwork high up in loft style bedrooms? (easily solves some duct run issues).