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Help my understanding!

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Cyclist77
Cyclist77 Member Posts: 269
in A-C, Heat Pumps & Refrigeration

Where I work,a bike shop, the building owner said to not not set the thermostat below 72F as it freezes up the unit.

So what it the real deal here about how low an a/c unit can function?

T! hanks

Comments

  • pecmsg
    pecmsg Member Posts: 7,311

    Freezing at 72°F return is a sign of oversized equipment on undersized ducts.

    In a work environment 72°F should be fine.

    Grallert
  • GGross
    GGross Member Posts: 1,990

    this may sound off topic but bear with me. I tell the delivery drivers that our receiving hours are until 3:30pm. hours are actually until 4:00 pm. this way if they are a little late they are still within our acceptable hours, I dont seem like i am being too strict, I give them half hour of leeway. the owner may be doing something similar with the stat. maybe they had an issue with an employee setting it too low and so they ask it be kept at 72, the reasoning is "you will freeze the coil" Bottom line though, if you aren't paying for it then don't touch the thermostat. 72 is fine in the summer, remember you could be in the south and have a boss not let you go below 78 to save money. Design criteria for cooling is based on 74f indoor temp, so you are able to keep it cooler than standard design dictates.

    EdTheHeaterMan
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 20,545

    If the system is sized correctly 74-76 degrees is usually fine if the AC unit is removing the humidity as it should be doing.

    Lowering the thermostat may force the indoor coil (evaporator) to run at a temperature below freezing (32) deg although with air movement the coil shouldn't freeze until 25 depending on humidity. Dirty air filters, undersized ductwork or not enough air flow can be a contributor as well as low return air temp.

    That said I have been on 100s of service calls where the thermostat set point is buried as low as it will go

    In my own house my GF keeps setting the AC at 70 or 72 and I keep raising it to 74-76 lol

    An age old problem but setting it to low can cause freeze ups under the right conditions.

  • Cyclist77
    Cyclist77 Member Posts: 269

    Thanks for your replies!

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