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Thread: Minisplit indoor temperature affected by outside air

  1. #1
    Join Date
    Jul 2020
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    Minisplit indoor temperature affected by outside air

    Hello experts,
    We just had a new LG minisplit installed (LMAN127HVP + LMN079HVT +LSN090HSV5 with a LMU30CHV condenser).
    One of the units is installed on an outside wall that the installer says it is not insulated. I think he saw the inside of the wall while he was making the hole for the lineset. I am a bit surprised but maybe.
    Yesterday it was very hot and my situation was as follows:

    Outdoor temperature 33C
    Unit target temperature 26C
    Indoor temperature 31C (as reported on the LG app which reads directly from the unit)
    Room temperature from an independent thermometer 26C

    The "indoor temperature" at the unit never moved from 31 C so the unit kept blowing cold air non-stop since it could not never reach the target temperature! The room temperature plunged to 23C

    The installer said "my guess is that hot air from the outside is entering through the lineset hole and the wall is not insulated".
    It seems like a good guess and in fact today, when it is not so hot outside, the unit is working as expected.
    At least it rules out a defective thermistor.

    Here are my questions:
    a) I thought that the indoor temperature is continuously measured via the air intake. Could the very small amount of air that gets in through the line set really make such a difference?
    b) Short of insulating the wall (a project for another time) do you have any other suggestions?

    We put some fabric insulation in the lineset hole from the inside (we did not want to mess with foam), but the opening is so tiny that I would be surprised if it made a difference. But maybe I am wrong.

    Please ask questions if something is not clear and please suggest away!
    Thank you in advance.

  2. #2
    Join Date
    Jan 2004
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    Insulate the hole from the outside.
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    How many times must one fix something before it is fixed?

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