need facts from the experts

[flamtap]

Hiya,

I'm in the market to replace my downstairs gas pack. I am in North Carolina. I've been looking up different things here for a couple weeks and now I have some questions.

I've had 3 different companies out for estimates. There are a few systems I'm considering but I need to get some facts straight.

Two of the companies did load calculations and both came up with a 2.5 ton requirement for the downstairs, which matches the current unit.

One company offers the Trane XL14c unit, but that is only available in 2 or 3 ton. The rep claimed that with the variable-speed blower the 3 ton unit would be able to efficiently remove humidity even though it is technically "oversized". The return would have to be made larger (16" to 18") but the rest of the ductwork would be ok. But a rep from another company claimed that it wouldn't work well at all. The blower would be too strong and my vents and return would whistle when the blower is at full speed. Plus I'd be paying for capacity I didn't need.

The Trane 13 SEER unit does not have variable speed. I'm interested in that because of the ability to remove humidity on the spring days where the temp is only 75-80 but high humidity. Will the 13 SEER be able to do that?

Also will a dual-fuel (heat pump) system save me much on cooling, or does the savings come in on the heating side there?

How much will I really save with higher SEER? Is it worth the cost increase for a downstairs unit in 2 story house?

Here are units I'm considering. Any advice for or against any of these would be appreciated.

Trane XL13c - 2.5 ton single speed, single stage cooling
Trane XL14c - 3 ton var. speed, single stage cooling
Trane 14 SEER dual fuel - 3 ton var speed,

Tempstar 13SEER, 2.5 ton, 2 stage heat/cool, var speed blower
Tempstar 14SEER, 2.5 ton, 2 stage heat/cool, var speed blower

Lennox 15 SEER, 2.5 ton, single stage cooling, var speed blower

Thanks again,
flamtap

[Daltex]

The 3 ton with VS blower will be good with a 2.5 load. The ducting is indeed needed to be sized for 3 tons to prevent noise and effeciency loss AT FULL speed. Most of the time the blower will be on a slower speed so the ducting could be ok. This need to be verified by the installer (manual D). Most higher eff. units are sold in 1 ton increments because the VS blower will handle the "sizing" to a point. If cost and effeciency are your only concern then go with the exact 2.5 with single speed blower. The VS units are a comfort issue. Yes the 2.5 can remove humidity. At lower outdoor temps. the unit will run less so less humidity will be removed. The heat pump will only save on heating costs unless the electrical cost is out of balance with the fossil fuel cost. There are calcs. avalible to determine this. Post your elect. / natual gas cost and someone here may be able to help. Won't save much SEER wise between 13 and 14 SEER. Correct installation is best way to save.

[BaldLoonie]

If the duct system is marginal or undersized, a 3 ton variable speed blower will ramp up to move the air it wants too. That's when things get NOISY!

The right sized single stage unit with dehumidify on demand ran by a Vision Pro IAQ will give great mild weather control. The Tempstar units have this feature, I would think variable speed Trane units would as well.

[super_tech_1]

trane 14 seer duel fuel. In your area it would be very cost effective. Going only what you tell me i don't have supreme faith in the other guy or the one that didn't do a load calc. You will have better humidity control with variable and using the heat pump mode in warmer winter times will eventually pay of assuming of course the price difference isn't to high. I'm not a trane fan at all either it just sounds like the better system for you.

[flamtap]

Thanks for the responses. I'm going to be talking with the most competent (so it seems) and recommended company again today and make a decision soon.