I am building a new home and the architect has included in his plans some information on HVAC requirements. I will be involved with the general contractor in approving bids. I have three questions.
1. Should I require HVAC contractors to provide a formal load calculation with the bid? Is this the only reliable way to get a correctly sized system?
2. I have two bids so far. The first bid is for a 2 unit York system (one 4-ton unit and one 2.5-ton unit, according to architect's specs). The other bid is from a Trane dealer who has provided a similar bid for 2 Trane units, then he has also provided a bid for a single hi-efficiency Trane (4 ton unit) unit with air handlers. What questions or concerns should I have concerning a single unit being used to heat and cool the entire house?
3. Last question. Is there some way to determine if the higher efficiency units actually make economic sense? I would like to have a higher efficiency unit but not if it has a 20 year payback period. Our climate is quite warm (California central valley) so I was thinking I should be more concerned about a high efficiency a/c unit but not so much about a high efficiency furnace. Is this the correct way to assess this issue.
Thanks very much for any advice.