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What is reasonable temp for a Unico A/C system?...

wcweaver3
wcweaver3 Member Posts: 52
in A-C, Heat Pumps & Refrigeration

Hi

I have a 2,300 square foot, 2 story home built in 1940. The house is served by a stand-alone (from the boiler heating system) Unico AC system with a 3-ton American Standard compressor outside using R22 refrigerant. The unit was installed in 2005. It is serviced each spring by a technician and was in good working order this past spring.

Over the past 2 weeks it has been wicked hot (90+) and I've noticed the A/C system has not been cooling as well as I remember. The suction tube, where it enters the plenum chamber inside the house, is cold and sweaty. The liquid line is warm. The thermostat is set at 71 degrees, and it manages to get the house to around 74/73 during the day. The temperature of the air coming out of the vent nearest the coil is 68 degrees and 53% humidity. The outdoor temp is about 88 degrees and 56% humidity. The condensate line is dripping water outside at a rate of about 5 drops per second. The filter was changed about 1.5 weeks ago. Most of the ducts run up through the attic and then down through the rest of the house. The coil and plenum chamber are in a closet on the second floor, not in the attic.

Are my expectations for colder air from this system too optimistic given the outside conditions or do you think I have an AC unit that might need to be serviced? BTW, I live in Pittsburgh, so the unit isn't running most of the year.

Many thanks!!!

Comments

  • Ironman
    Ironman Member Posts: 7,550

    If you’re only getting 68* supply air and the house is 74*, then you need to have it checked out.

    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • pecmsg
    pecmsg Member Posts: 5,297

    time to call for service

  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 16,488

    Supply air should be more like mid 50s with a 75 return or should be dropping the air about 20 degrees.

  • wcweaver3
    wcweaver3 Member Posts: 52

    Many thanks for the great guidance @Ironman , @pecmsg and @EBEBRATT-Ed - really appreciate it. The Service Technician arrives tomorrow.

  • corgi11
    corgi11 Member Posts: 81

    I helped install a space pak 3 ton unit using R 22 In my house in 1975. I am still using that unit.

    I checked my old manual and this is what it says

    There should be a 20-30 air temp degree drop across the evaporator. Do not check charge at 65 degrees or lower. My unit has always been running at a 30 degree drop and takes humidity out of the air like a sponge. Because the humidity is low I can be fairly comfy with my air set to 78.

  • wcweaver3
    wcweaver3 Member Posts: 52

    @corgi11 - thank you! I had it recharged and all is good now and I know what temp drop to look for.

  • pecmsg
    pecmsg Member Posts: 5,297

    now you need to find and repair the leak.

  • ratio
    ratio Member Posts: 3,791

    What @pecmsg said. Refrigerant doesn't get used used up, it only leaks out. At $$$/lb, it's an expensive leak.

  • corgi11
    corgi11 Member Posts: 81
    edited August 11

    I hope you also realize also that since you are never going to find a replacement outdoor condensing unit that uses R-22, that one day you and I are going to have the entire Space-Pak or Unico unit replaced in the attic and outside as well The new units use R 410a. Also the new units require more outlets per ton of cooling.

    It is going to cost us a fortune when we have to replace them!!!

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