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  1. #14
    Join Date
    Jan 2007
    Location
    Nashville
    Posts
    9

    Superheat mystery

    There must be a flaw in your temperature measurement. You can't have too low superheat at compressor unless you are over-feeding your evaporators.
    Have you checked to see if your strainers are clogged on your TEV's. If your system is designed properly and if you have a full column of liquid at your valve, you should be able to get proper superheat.

  2. #15
    Join Date
    Jul 2005
    Location
    FLORIDA
    Posts
    1,163
    just a theory here but could one of your valves be open while the other is closed a little to much

    i would go there and pump down system and clean those valves to start and then throw that baby into a defrost to creat a load and put the valves back to factory setting [ q body total turns is 8 1/2 out of the box so it should be at 4 1/4 from totaly closed ] g body 10 turns out of the box ] now fill that glass and see whats up with super heat and should be out of defrost by now with a load
    once you think you've seen it all
    (THINK AGAIN)
    I would rather work for free than be look upon as a thief!!!!!

  3. #16
    Join Date
    Jul 2000
    Location
    Guayaquil EC
    Posts
    10,081
    Quote Originally Posted by leathernecke5 View Post
    ....Uh how can I have starving evap and a low superheat at compressor.....Low Side pressure is the same at outlet of evaps, suction filter port and Suction Service Valve.........
    Something doesn't add up here.

    Did you actually measure these suction pressures to be the same using access valves or was this assumed? What instrument are you using for your temperature measurements?

    You can't have a lower SH at the compressor than at the evaporator outlet unless liquid refrigerant is being introduced into the suction line somewhere in between. The only times I have ever seen this happen is when there was a suction/liquid heat exchanger with an internal leak or with a TEV that is leaking through the equalizer line to suction.

  4. #17
    I assure you Sir I checked and rechecked the superheat temps and it drove me nuts. Now I will also tell you what I recently found out. The Compressor is rated at 11,100 BTU's low temp at -25 degrees. The two (2) evaps are rated at 9600 BTUS's. It seems this entire system was a put together piece mill. The compressor superheat drove me absolutely nuts never seeing that before. But I will tell you all that upon disconnecting the condenser fan motor the liquid line temp started to rise and some bublbles started to appear in sight glass. I really think that maybe a faulty Headmaster, I'm contemplating just setting up 1 evap in conjunction with the compressor and adjusting with condenser fan cycling control. Some of you think Headmaster is faulty. But I never saw a situation where evaps are starved and compressor superheat is way low. Temp was checked 6" from compressor.

  5. #18
    Join Date
    Dec 2006
    Location
    In a Mess
    Posts
    992
    just grab on to the headmaster to see if it is bypassing gas, you should be able to feel the temperature of the lines, not a sure way to test but could give an initial clue, especially if there's any lenght to the piping at all. like i said not a sure fire way to test but may give ya an idea of operation

    -Mike
    Sig removed by mod. G-Rated site

  6. #19
    Join Date
    Apr 2005
    Location
    where the beer flows like wine
    Posts
    2,871
    I encountered a similar situation today, Kolpak walk in, TXV whistling big time, condenser in the roof, unit less than 8 months old, compressor and fan short cycling off LPS, discharge 142 psi,suction 8psi, 404a, headmaster bypassing, it took the last 8lb I've left to get the head pressure to 174psi, superheat down to 15F. with the condenser totally blocked the head pressure stalled at 180psi, clear sigh glass and headmaster bypassing, box temp came down to set point.
    I going to make a switch to cycle the fan on and off manually instead of blocking the condenser.

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