Old 01-16-2008, 07:35 PM
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Join Date: Aug 2006
Location: NJ
Posts: 490
Default Re: Mis-matching HVAC system (replacing outside unit without touching inside)

jwb - 1/16/2008 8:30 PM

The system will not be "mismatched". All that will happen is the SEER will actually fall between 12 and 13. Not a big deal. The primary difference is the size of the condenser coil. A larger coil yields a higher SEER rating.
After the condensing unit is installed, with a drier and properly leak tested, evacuated and charged the entire system should be evaluated. At that time you can check temperture splits on the evaporator (18 - 22 degrees) to determine proper airflow ( eliminating dirty coils, poor duct design, closed diffuser grills, dirty air filters). Then check superheat at the outlet of the evaporator(12 degees) and subcooling on the liquid line (10 degrees). Finally check refigerant pressures and amperages. If all this is acceptable your system should run fine. If I read the OP first post correctly, the system is functioning now. I would do the evaluation now and eliminate any indoor related problems.
I have NEVER had a warranty issue with a manufacurer or wholesaler by replacing a condensing unit on an existing indoor unit. Hell, they just give you the replacement parts and ask for proof of purchase date. If there are any warranty issues it's with the contractor, not the equipment manufacturer. Really, this is a simple job.
BTW, we used to do hydroair installs all the time. This involves a First Company indoor unit with a built in hot water coil. They didn't make an outdoor unit so we matched it to Tempstar condensing unit. No problems.
I think JWB needs to take a refresher class in hvac.
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