I think this is called a gravity coil
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  1. #1
    Join Date
    Jul 2006
    Location
    Ca
    Posts
    28

    I think this is called a gravity coil



    it has worked in a 2ft. wide pie case with r-12 and 409 for the past 50 years. There is also a reach in just below it parallel with the same line set, only the reach in has a LL solenoid with a t-stat, all med temp. I assumed the coil above cycled on the low pressure switch in the condensing unit.

    I matched BTU's from old condensing unit with the replacement 404 unit, changed evap unit below unit and put new txv's on both the air blown evap below and this "gravity" coil above, increased LL size to 3/8 and charged it up.

    The head pressure goes through the roof when the reach in below makes temp and cycles off. With both coils functioning, I got the superheat dialed in and pressures close to perfect but soon as it cycles and the gravity coil above is alone (no LL solenoid, never was)...head pressure climbs above 500 psi.

    How did this r-12 system work all those years? What am I missing here, is 404 impossible to get correct? I know ice machines use gravity coils and 404.

  2. #2
    Join Date
    Jul 2006
    Location
    Ca
    Posts
    28

    picture of coil



    Sorry, I tried to paste a link of a picture but not sure why i dont see it in thread

  3. #3
    Join Date
    Oct 2004
    Location
    Central WA
    Posts
    1,454
    Sounds like you are overcharged or your receiver is too small.

  4. #4
    Join Date
    Jul 2001
    Location
    Gold Coast of Connecticut
    Posts
    4,567
    yep
    Aire Serv of SW Connecticut- Gas heat, dual fuel and central a/c systems installed and serviced

  5. #5
    Join Date
    Oct 2011
    Location
    Chicagoland Area
    Posts
    4,498
    Officially, Down for the count

    YOU HAVE TO GET OFF YOUR ASS TO GET ON YOUR FEET

    I know enough to know, I don't know enough
    Liberalism-Ideas so good they mandate them

  6. #6
    Join Date
    Jul 2006
    Location
    Ca
    Posts
    28

    yeah...

    The high side gauge went bad. It read about 300 lbs higher than it should. The system is all good now. I failed to look at the most obvious problem after a hot day on a roof. Anyhow, that's my excuse.

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