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New to AC

Matching the outside unit to the inside. So 30 years ago my father removed the outside AC unit from their vacation home in South Eastern Virginia. Some good reason at the time, between lower taxes on non AC homes, extensive remodeling and real men don’t need AC. LOL. So now the condenser in the attic space that blows air, a drip pan that does not leak and the system worked when disassembled has me looking for a good outside unit. I expect the two units are sized to fit each other? How close do they have to be? No obvious tag info on the air handler. Is there a way to measure the condenser and determine how many tons? Sorry if I am using the wrong terms. Measuring the “A” coil?


    JUGHNE Member Posts: 10,914
    30 years ago system were most likely R-22 gas.
    That was phased out a few years ago.
    Were the lines capped to prevent moisture/air from entering?

    Short of a complete new system, you might get lucky with a used (good luck) outside unit which is the condenser.
    The coil in the attic is the evaporator.

    The model of the coil itself could give you the tonnage size of what the system was.
    HVACNUT Member Posts: 5,479
    Penny wise, pound foolish. Get 3 estimates for a new high efficiency CAC system complete, with new refrigerant lines.
    What's there now doesnt mean it's right. Need to do a Manual J heat gain to size it correctly.
    Click on find a contractor in my area and see if anyone here can help.
  • Ken D.
    Ken D. Member Posts: 836
    R407C units were close to R22 and was an option, but I don't think they are available anymore. Check with your supplier. You could get lucky, but an R22 indoor unit will probably not work with a 410A outdoor. 410 operates at a much higher pressure than 22, so leaks are likely. The expansion device will need to be changed. If it has cap tubes, it's more of a problem. Also, the volume of refrigerant the coils hold is an issue, as is the size of the lineset. The old coil might not have the volume or surface area for good cooling. You can end up either flooding the compressor or starving it. Neither is acceptable. You could void the compressor warranty. Check the fine print. If you use a TXV, you could use trial and error to adjust it to bring your superheat and subcooling in line. Even then the coil is probably not compatible. Check out the physical size of a new 410 coil compared to a like tonnage 22 coil. See what I mean? You have to make sure all of the old mineral oil is flushed out. If you do go ahead, you're not going to get the rated SEER, it is going to cost more to operate. In the long run, a whole new system with a new lineset will be longer lasting, more economical and less of a headache.