5-ton AC unit at altitude: Trane xl15i

[laaf]

We just received to competing quotes for installing AC and a variable speed, 2-stage furnace. Now we are more confused than when we started!

The question: One salesman refused to sell us a 5-ton Trane AC unit without us signing a waiver (I think the waiver said it may freeze up at our altitude, Denver area), while the second salesman said we absolutely needed a 5-ton AC for our 4200 square foot house (including 1200 in basement, so 3000 sf upper levels). Has anyone ever heard of not using 5-ton AC units because of their performance at higher altitudes?

[hvaccolo]

I am a mechanical contractor in Denver, and I'm not really sure why they are trying to scare you off of a 5 ton unit...the altitude will not cause freeze up problems here. If you need to use the AC on days when the outside air is a little cool (under 70) I would install a condenser fan control system of some sort (like a p-66). As long as the furnace they are selling you has a 5 ton drive system, and your duct system will handle the 2000cfm, shouldn't be a problem.

I would be more concerned with the electrical system handling the power requirements of a 5 ton. That's a lot of amps on a residential system.

If you're going to spend the money on a 2-speed furnace, I would recommend you look at a hi-efficiency furnace, instead. As you know, in Colorado, if the sun is out, the furnace is just for show...when the street lights come on, you will probably need the high speed only...the high-e furnace will be a better bet for energy savings.