Cursed 5 ton zoned system.

tgkxAugust 14, 2011

Hi everyone, i need help as i feel ive run out of ideas. I have a two zone 5 ton carrier ac in my new 2800 sq ft home. It is two stories. I have had two separate companies out at least seven times each trying to fix problems with condensation on the outisde of the air handler in the attic and the system tripping the DATS sensor for too cold.

Tonight i measured the air temp with a probe just after the evap coil and it read 53 degrees. The air before the coil read 77 degrees. I also measured some places on the exterior of the air handler with a infrared sureface gauge and got readings in some places at 55 degrees and at others 45 degrees!

What is wrong with this cursed system causing it to sweat so badly and get surfaces so cold???


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5-tons in a 2800sq ft home with zoning! Where do you live, on Mercury?

Seriously, was a Manual J load calculation done? Post the model numbers for all the equipment installed.


    Bookmark   August 16, 2011 at 12:24AM
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As a follow-up, can your zoned duct work handle 5-tons?


    Bookmark   August 16, 2011 at 12:27AM
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Hey just saw your followup. I almost live on mercury (Houston, TX).

Models are as follows:
Carrier 58STA110-22 130 Series furnace
Carrier 24abb460a310 compressor
Carrier cnphp6124ataabaa coil
Honeywell HZ311 damper control board

We've been through numerous iterations trying to get enough ducting to properly flow 5 tons worth of air. Right now we have a supply plenum that feeds two rectangular dampers (1 for each zone) which are apparently rated at 1100 CFM each. There is also a bypass damper with the weighted arm for adjusting the extra air, its run with 12" flex. It loops way back around into a mixing box on the return side.

Current problems are its sweating on the outside of the supply plenum. The furnace blower is set to high speed. AC company measured static pressure (took a reading at the return side and supply sides) and said it was .4. Specifically, he measured at the return before the air hits the filter and on the supply side after the coil.

I can get you any other info ya need such as air temp etc.

    Bookmark   August 29, 2011 at 10:19PM
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