Help with sizing?

[06Corvette]

Yep. I was combing through the AHRI site tonight and discovered that Carrier's units list the 5 ton for efficiency quite a bit.

What is the hit to go to the MVC furnace? It looks like that's a premier unit, and quite frankly, nobody around here has been quoting anything over 80% AFUE. The story you get down here in Texas is put the money in cooling, not heating.

However, I did find one combination that seemed to fit. Is this the one you were referring to with the 4 ton coil and 90K furnace? I'm not an HVAC guy.

Carrier
Performance 17, 4 ton, 24APA748A**31
Performance series 4 ton coil, CNPH*4821A**+UI
Infinity 80, 90,000 BTU furnace, 58CV(A,X)090-16

This combination comes up at 16 SEER, 13 EER. And it seems to match 4 tons all around.

But you're right. There was nothing much else available. The only other option I saw that was interesting was this:

Carrier
Performance 17, 4 ton, 24APA748A**31
Performance series 5 ton coil, CNPH*6124A**
Performance Boost 80, 90,000 BTU furnace, 58PH*090-16

Thie combination is 17/13.4, but I don't think the furnace supports two-stage - not that it's essential.

I will inquire on the 21, but I don't think I can swing that if I can't get the tax credit on a well matched system.

Look into it. best bet is to go with the 2 stage cva 90000 with 4 ton unit and coil with infinity stat--you get federal and manufacturer sal tho save about 2500 there so far.

[swendler]

Look into it. best bet is to go with the 2 stage cva 90000 with 4 ton unit and coil with infinity stat--you get federal and manufacturer sal tho save about 2500 there so far.

Searching on the 58CVA090 furnace, the biggest Infinity 21 system I can find that qualifies is a 3 ton (although they qualify very easily). What am I missing?

I did see an Infinity 21 4 ton that was paired with a 5 ton coil and the two-stage 58MEC100. That was as close as I could get.

[swendler]

I kinda touched on this equipment before, but I am interested in hearing opinions on the following tradeoffs.

I think I'll be going with the 4 ton 24APA7, but which matchup is better advised?

...the 5 ton CNPHP coil and the 110K 58CVA furnace, which achieves 17 SEER and 13.5 EER? (Better efficiency due to bigger coil.)

...or the 4 ton CNPNP coil and the 90K 58CVA furnace, which achieves 16 SEER and 13 EER? (Better balance of furnace size to need.)

I'm in Texas and 80-90% of our energy cost is cooling.

I realize that the 110K furnace is more heat than I need, (heck, even 90K might be considered too big), but I'm wondering if the additional 1 SEER point and 0.5 EER point would help me with utility costs in the summer months more than the detriment of being oversized in heating?

I'm currently running 115K single-stage, which is WAY oversized. At least the 58CVA is two-stage.