New build house in Houston Texas area. Not many heating days, but lots of humidy and heat. Icynene foam insulation with the attic part of the latent conditioned airspace. Insulated steel ductwork.
Will be going with a Carrier Infinity system. Based upon the manual J calcuations, installer is reccomending a 4 ton downstairs with ERV and two zones. Upstairs will be 3 ton with ERV with two zones. Both will be mated to variable speed air handlers and Infinity 96 lpg furnaces.
Both reccomended ACs are the 17 SEER units. The question is if it is worth it or not to move up to the 21 SEER units. To upgrade both systems would cost 1,600 additional. I like the ideal of moving to the scroll compressor, but then the low speed moves from 50% to 70%. The heat gain per zone is 60-40 downstairs and 65-35 upstairs.
Not sure the additional SEER would pay out or that it would suit the current zoning requirements.
Thoughts or suggestions?