Assistance with replacement HVAC
First off, I'd like to thank the professionals and knowledgeable people who generously share their time and experience on this forum. Without them, I most likely would have gone with an oversized and possibly poorly designed system.
I'm currently remodeling my newly bought home and will be replacing the existing HVAC system (including all ducts). I've never used the current system because I never moved in, but it was a 5 ton Goodman condenser and a 85000 BTU 80% AFUE Carrier, both about 14 years old. The 3250 sq ft house is in southern california, about 50 miles inland. I will be upgrading the house with new insulation (R30 attic and R13 all exterior walls) and new windows (LoE 272 on north and east sides, LoE 366 on south and west sides). We had a Title 24 done as part of the planning process and they came out with approximately 32,000 BTU Heat Gain and 41,000 BTU Heat Loss, with the planned upgrades. I used HVAC-Calc (thanks for the previous thread), raised the outdoor summer temp 5 degrees as suggested, and came out with 48,500 BTU Heat Gain (46900 Sensible), and 64,000 BTU Heat Loss. It's likely that some of the difference was due to the windows, since HVAC-Calc doesn't go into great detail about the different possible glazes and ratings. Based on these calculations, does a 4 ton system seem reasonable? Any suggestions for furnace BTU rating? It will be a 2 zone system. I'm working out the details for some quotes I've received and hope to get them posted shortly. Some of the contractors will do an official Manual J, but only after the contract is signed.