Help experts! need A/C recommendation advice NOW

[glewis29]

Cmajerus,

Odd that you say you like Trane but recommend a bypass damper for when only one zone is calling.

In the system that I had installed, we did a dual compressor so it only uses 2 tons of cooling for small rooms. If the zones that need cooling are not cool in 10 minutes then the 4 ton compressor will kick in. If for some reason, the system is calling for 4 tons of cooling, but it's too much CFM for the zones that need cooling (as determined by percentage weights on the zone boards) it will do a strategic relief to other zones of the house (this doesn't happen very often) Because of the strategic relief capabilities of the board they contractor didn't install a bypass damper (I don't think there would have been room for it anyway, the space is pretty tight)

The one downside of this integrated Trane system is it doesn't accomodate for humidity (that I know of). However living in Southern California, that's not usually much of an issue (it was a very humid summer and we hit ~65% RH)

Hope that helps...

[cmajerus]

Cmajerus,

Odd that you say you like Trane but recommend a bypass damper for when only one zone is calling.

In the system that I had installed, we did a dual compressor so it only uses 2 tons of cooling for small rooms. If the zones that need cooling are not cool in 10 minutes then the 4 ton compressor will kick in. If for some reason, the system is calling for 4 tons of cooling, but it's too much CFM for the zones that need cooling (as determined by percentage weights on the zone boards) it will do a strategic relief to other zones of the house (this doesn't happen very often) Because of the strategic relief capabilities of the board they contractor didn't install a bypass damper (I don't think there would have been room for it anyway, the space is pretty tight)

The one downside of this integrated Trane system is it doesn't accomodate for humidity (that I know of). However living in Southern California, that's not usually much of an issue (it was a very humid summer and we hit ~65% RH)

Hope that helps...

I have seen a setup like that once, it works well also, we install bypass relief dampers on most single stage zone systems, but have used a system that used a minimum positon on all zone dampers instead of a relief bypass, and that seems to work without overcooling or heating the zones that aren't calling, but that system is in a pizza joint and it is calling all 3 zones most of the time anyway.

[glewis29]

Yeah, I can see how the minimum damper position would be valuable for something like that. For me, since I don't use the upstairs of our house except for entertaining (no kids), being able to turn off the upstairs completely has been very valuable. From plotting the electrical bills in excel I figure out electrical usage for A/C has dropped from $1200 a year to closer to $400 due to the zoning and higher efficiency unit (the old one was 30+ years old).

[cmajerus]

Yeah, I can see how the minimum damper position would be valuable for something like that. For me, since I don't use the upstairs of our house except for entertaining (no kids), being able to turn off the upstairs completely has been very valuable. From plotting the electrical bills in excel I figure out electrical usage for A/C has dropped from $1200 a year to closer to $400 due to the zoning and higher efficiency unit (the old one was 30+ years old).

wow! very nice, won't take long to recoup that investment. Always good to see that much of a difference in energy usage.

[herrerao]

First thing i will do, run the load calculations manual J and manual D and compare the results with what you got. then get a good seer unit.
and a good tech for the installation.

[mo in cincy]

Herrerao
Thanks I watched him do them. he measured all windows doors and had room sizes off the county building plans web site. I have all that what I was looking for more was a cover here a plate there a different valve???

Mark

[sellshomes]

I'm thinking 5 hours,that's a long way in my book!!

I just received an extensive proposal via email, can I forward it to you for your review and comments, there are several system options, including duct and IAQ options. You opinion would be greatly appreciated.

I will gladly pay for your time with a supply of beer and pizza.
Please email me if you have the time.
Thanks,
Steve (sellshomes)