This is my 1st post. I've lurked at this site for awhile. Lots of knowledgeable folks! I'm about ready to sign a contract with one of the HVAC contractor for my yet to be built new home. I'm somewhat concerned about the size of the units the contractor spec'd out which I think is too large (in my inexperienced opinion!). I hope some of you won't mind giving inputs.
Here's the brands and spec's (I spec'd out 2 stage units with 2 stage thermostats). Lennox G61MPV 110,000 BTU 1ST floor, 90,000 BTU 2nd floor; HSXA19 (probably mis-spelled in contract, should be HSX19?) 4 TON 1st floor, 3 TON 2nd floor. Lennox Signature thermostat and WB2-17 humidifier will be included. Here's the info on my new house: approx 3700 ft2, 2 stories with 2 story front foyer (100 ft2) and 1 1/2 story hearth room (224 ft2) at the rear opening up to 2 story breakfast room (200 ft2); 1st floor, 9' ceiling, 1950 ft2, front of house facing west with 108 ft2 of windows, back of house facing east with 234 ft2 of windows; 2nd floor, 8' ceiling, 1650 ft2, front house with 108 ft2 of windows, back of house with 80 ft2 of windows. House construction is wood framed with R19 walls (2x6 framing) and R38 vented attic. Windows are vinyl, low E, triple pane. The full basement will be unfinished. The house will be fairly air tight (I will try to seal all potential leaks and apply mastic to all ducts). Location is St.Louis, MO.
I did asked for them to do a Manual J calc, but did not think about D calc. My wife got the heat/loss gain calc over the phone which from what I remember off my head (don't have #'s with me now) is around 90,000 1st floor/30,000 2nd floor. Is this about right? I cannot remember the calc for the A/C.
Also, I'm debating on whether I need HRV or fresh air intake (I don't think I need fresh air since I will not have above 300 cfm kitchen vent and above 100 cfm bath vents). How do I know whether I need one of this system or not?
[Edited by miked2 on 08-03-2005 at 08:50 PM]