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  1. #1
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    Pie case design temps

    Hello

    I just changed a 5' pie case from R401a to R134a.

    TXV with receiver.

    I'm running a 10 degree evaporator with a 40 degree box. Is this normal?

    Does anyone have a chart with common design temps for different applications?

  2. #2
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    Typically I see R134a medium temperature refrigeration at 15 psig. or 15 SST.

  3. #3
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    Is there a sight glass ?

  4. #4
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    Fan or gravity coil?
    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

  5. #5
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    Thread Starter
    Quote Originally Posted by 2sac View Post
    Fan or gravity coil?
    Fan coil. Two 1/100 hp about 6 inch fans

  6. #6
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    Clear the Sight Glass

    Test and adjust the SH 6" from the compressor between 20 & 40F

  7. #7
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    Thread Starter
    The sight glass is clear of bubbles. I don't know if it a higher velocity than most systems I have seen because I can still see the liquid moving.

    Before removing the 401a, there were definately bubbles. SH was 35+ at the exit of the evaporator

    I charged to a clear sight glass with R134a and adjusted for 10SH at exit of evaporator. Liquid line is soldered to suction line. This gave me about 45SH at compressor.

    Condenser is about 111F saturation in a 70 degree room
    Evaporator is running about 10F

  8. #8
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    Quote Originally Posted by mjohnson2981 View Post
    The sight glass is clear of bubbles. I don't know if it a higher velocity than most systems I have seen because I can still see the liquid moving.

    Before removing the 401a, there were definately bubbles. SH was 35+ at the exit of the evaporator

    I charged to a clear sight glass with R134a and adjusted for 10SH at exit of evaporator. Liquid line is soldered to suction line. This gave me about 45SH at compressor.

    Condenser is about 111F saturation in a 70 degree room
    Evaporator is running about 10F
    Close the valve, try and get 30F at the pump.

    Compressor SH trumps evaporator.

    Measure the discharge temperature before and after adjusting the valve. 200 -225 is the limit!

  9. #9
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    Is this a remote setup ?

  10. #10
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    Thread Starter
    Quote Originally Posted by VTP99 View Post
    Is this a remote setup ?
    Self contained unit

  11. #11
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    Thread Starter
    Quote Originally Posted by pecmsg View Post
    Close the valve, try and get 30F at the pump.

    Compressor SH trumps evaporator.

    Measure the discharge temperature before and after adjusting the valve. 200 -225 is the limit!
    I measured discharge at 165F but it was about 18 inches from the compressor. I need a smaller thermocouple to get closer.

  12. #12
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    Thread Starter
    It was pretty consistent with readings until just before I left. It would turn on level off about 13psi with 10F SH at the coil then all of the sudden it would go to 0 SH at coil and 9 psi on suction and cycle off on the control.

    I thought for a second that maybe the supco88 or small POE addition broke something loose plugging the TXV but a restriction would make SH rise and pressure drop, right?

    If the valve opens and dumps refrigerant the PSI would come up and SH would drop.

    It was late and I let it ride for a day or two. I'll go back and see how it is acting. It was doing the same cycle several times in a row.

  13. #13
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    Liquid solenoid, low pressure switch ?

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