Mr asked in Home & GardenMaintenance & Repairs · 6 months ago

What is the direction of coolant flow in a household central air conditioning unit?

Does the coolant leave the outside unit and flow inside via the big pipe and return outside via the small pipe or is it vice versa?

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  • elhigh
    Lv 7
    6 months ago

    Vice versa.

    The small pipe is the high pressure line and is going from the condenser (outside) to the evaporator (inside). The cold line is the one coming back outside.

    NOTE: a heat pump has a solenoid-operated valve that allows it to pump the refrigerant the other direction. In heating mode, these directions will reverse.

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  • Mitch
    Lv 5
    6 months ago

    just the opposite. the refrigerant gas is compressing in the outdoor coil, the outdoor fan blowing the heat out of the refrigerant there helps condense that gas to a liquid in the small line entering the indoor cooling coil. At that point the liquid expands through an orifice or other type of metering device where that liquid refrigerant expands to a gas and due to the large temperature difference will absorb a lot of heat. It may seem cold coming back on that larger line but there is a lot of heat absorbed in it. Its larger to reduce pressure drop back to the compressor and is insulated to protect from moisture damage to the structure and helps cool the compressor. Ductless units operate somewhat differently and meter refrigerant starting at the outside unit so both lines are insulated.

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  • 6 months ago

    the insulated line outside is the one with the chilled coolant in it. they're the same size on mine. most owners aren't competent to be working on the a/c anyway

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  • 6 months ago

    Counter clockwise.

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  • Edwena
    Lv 7
    6 months ago

    Vice versa, Going in, the coolant is under high pressure. Since it is compact, it uses the smaller pipe. At the coil there is the pressure reduction which produces the cooling. The coolant is then at a lower pressure and requires a bigger pipe to return to the compressor which is located outside.

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  • ioerr
    Lv 7
    6 months ago

    i'm not an expert but i believe it comes in through the little pipe, in compressed form. inside it goes through the expansion valve, getting really cold, so it can cool down a lot of air, then it goes back outside in the big pipe to be compressed again out there. on the way out it carries some heat it picks up from the air it cooled down in there, and heat is dispersed in the outside unit

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    • Edwena
      Lv 7
      6 months agoReport

      It's cold and moisture will collect on the outside of the pipe and drip. It would be wet. Note that your PVC condensate line from the bottom of the coil to the sewer drain is also insulated, The condensate is cold, so the pipe cold. You would have a drip in the attic from moisture on the pipe.

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