not cooling - http://www.hvacmechanic.com/ Forums
Original message
| hotnmad
 |  "not cooling"
, posted Wed 16 Jul 16:46  
I have a two month old 2 1/2 ton trane unit.
During a 90 deg day the unit runs 8 hours to keep the temperature 80 deg inside the room.
Here is what I know:
Attic temperature 130 deg and pretty well vented.
Walls and ceiling are well insulated (the wall temp and ceiling temp match the room temp of 80 deg)
The air temperature at the R/A filter is 80 deg.
The air temperature at the closest diffuser to the unit is 67-68 (12 to 13 degree drop). At night this spread will go to 15 to 17 degree drop.
There is no sweating on either of my copper lines at the outside unit.
What could be my problem? I'm not getting much help out of my contractor who installed it 2 months ago.
Thanks.
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Replies:
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| Freon
| "Re(1):not cooling" , posted Wed 16 Jul 16:51
Model number? Running all day on the hottest days is good. However your temperature drop seems anemic. That could be a function of air flow through the coil or an improperly charged system. Much depends on the type of system you have.
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| | hotnmad
| "Re(2):not cooling" , posted Wed 16 Jul 18:53
Trane Model# XR13.
It is a plane flat ceiling (8'6") and has a door to the stairwell. We've tried it open and closed...does do a little better with the door closed but not much.
thanks.
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| | Freon
| "Re(3):not cooling" , posted Wed 16 Jul 19:00
The only other possibility is poor insulation in the 2nd floor ceiling. Your cool 2nd floor makes the work for the first floor unit easier. All I can suggest is have a tech get you the subcooling and superheat readings so you know what's really happening. What is the indoor coil model number? Were both the outdoor and indoor unit installed at the same time? Do you live in a high humidity climate, like Houston, TX?
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| | hotnmad
| "Re(4):not cooling" , posted Wed 16 Jul 19:12
i have 12" of blown in fiberglass insulation and an additional 6" of blown in cellulose insulation. when this problem first started i assumed the problem was in the insulation so i re insulated all ceilings and walls. the results were drastic..before re-insulation i could only get the temp down to 88 degrees..now i can get it down to 78 but it has to run all day to do it. i have recessed lights that allow for the insulation to cover the lights. i've checked every square inch of the ceilng with an infrared thermometer and there are no hot spots...the ceiling temp is only a degree or two higher than the room temperature.
i am highly suspecting my problem is a 16" (outside dia) 20' run (with 3 ells) return air duct. does that sound like too long of a run????
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| | hotnmad
| "Re(2):not cooling" , posted Wed 16 Jul 17:03
i'll have to check on the model number.
it does not seem right for it to have to run all day to keep the temp only at 80 deg. if i was asking it to get to 68 deg i would understand.
it is cooling 800 sq ft upstairs and i have one right beside it cooling downstairs that runs 4 hours a day to keep the temp at 75 deg.
i realize one is upstairs and one downstairs but still something does not seem right.
what about the no sweating on the copper lines? could that be right?
i'll get more details tonight and post again.
thanks for your reply.
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| | Freon
| "Re(3):not cooling" , posted Wed 16 Jul 17:56
If it's cooling the upstairs and there's an open stairwell or cathedral ceiling design, then all that 2nd floor cold air sinks to the first floor. 2nd floor cooling can be a challenge The duct system, especially returns on the 2nd floor, becomes important.
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