AC SEER Selection

[d6btex]

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?

Thanks

[gary_g]

Post model numbers of the condensers (outside units), matching indoor coils, and furnaces.

Most "up to 21 SEER" systems are not 21 SEER, or they are 21 SEER only in a few model numbers on smaller sized units.

Model numbers provide info as to SEER, EER, and actual system btu's.

Good luck.

[beenthere]

The 17 SEER (Bristol TS compressor) will probably be better for you zone sizing.
You are going to use the Infinity zoning system right.

[Mr Bill]

IMO, in Houston anything over a 14 seer is really a waste of money if your trying to recover any from the higher seer units. We have sold one 16 seer RUUD system and from the performance I saw from it compared to equal 14 seer equipment, the 14 seer performed just as good and was better on latent removal. But then again I am not big on the really high seer stuff to me it's just more hype.

[d6btex]

Yes we will be using the infinity controls. I think the 17 SEER is actually about a 15 EER. As you say, with the heat load as presently zoned, I think 70% would be too high.

The 17 SEER (Bristol TS compressor) will probably be better for you zone sizing.
You are going to use the Infinity zoning system right.

[udarrell]

IMO, in Houston anything over a 14 seer is really a waste of money if your trying to recover any from the higher seer units. We have sold one 16 seer RUUD system and from the performance I saw from it compared to equal 14 seer equipment, the 14 seer performed just as good and was better on latent removal. But then again I am not big on the really high seer stuff to me it's just more hype.

I agree, watch out for the sales pitch & the charts based on lab conditions.
In real world conditions, I like the 14-SEER with a good scroll compressor & a TXV.
http://www.udarrell.com/aircondition...l_systems.html
- udarrell

[alex_in_fl]

Best bang for the buck - upgrade the upstairs unit only.