I'm looking for a few opinions (I know, there are LOTS of opinions here).
Over the last few years, I've been evaluating replacing an existing Carrier AC system in my home. The existing unit was built in 1987 and has been working fine, though I suspect it's days are numbered. Hence I've been comparing options.
Based on my own rough Manual J, as well as estimates of a couple contractors that have been out here, the house should have about a 4 ton unit. Currently it's running with a 5 ton unit (the previous owner always liked to supersize everything...) so I'm stuck with a system that doesn't effectively remove moisture or maintain a stable temperature. So I'm looking at making some changes.
Today I had a guy in who strongly pushed a Unico high velocity system
- tear out all the existing ductwork and replace the entire system. I hadn't considered this previously because, well, it seemed like overkill. But I'm comparing all options. So that's option 1.
A second option is to replace the existing units with a nice variable speed air handler and two stage compressor, keeping the existing ductwork. That's appealing as it should be quite efficient and maintains the investment in ductwork (which the contractors have told me was quality work).
The third option is to do option 2 and add another zone. This would require some additional ductwork but the guys I've talked to said that the current ducting is set up pretty well for this addition.
Here are my specific questions:
1) I've heard that the HV systems can be noisy and inefficient. This makes intuitive sense since the HV systems will require more energy to push air around. Smaller tubes = greater resistance. Plus, higher velocity would imply higher turbulence and hence more noise, though I've heard this is offset for by lower overall CFM.2) I've heard that HV systems can be considerably more pricey. I'm waiting on the proposal, but from what I've heard, $10-20k is in the ballpark. Is it a rule that HV systems are considerably more expensive than a modern, 15 SEER dual stage, variable speed system? Or are people comparing them to run of the mill systems? For reference, last year I had a quote of $6600 for the retrofit including a Carrier
38TDB048-3 and FV4BNB006000 (with all labor etc.) which seems like a pretty decent price.3) While the air flow isn't optimal and I think a two zone system is warrented for maximum comfort, is there any reason why I shouldn't go for the simple upgrade, see how it feels next year, then add the second zone if necessary a few years down the line? I've lived with the current non-optimal setup for 5 summers so far and it really hasn't been such a big problem. I understand that it will cost more if I do it in two shots, but are there any other fundamental reasons why I shouldn't go this route?
Thanks for the feedback.
-Ted