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  1. #27
    Join Date
    Mar 2006
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    Quote Originally Posted by tech93 View Post
    suction pressure is to high to be a txv.suction pressure would have to be below 10psi to feed enough liquid to raise discharge pressure.
    i agree the suction pressure is too high for the desired temp range, ill look at adjusting the txv tomorrow before i look at replacing it, what is a good superheat range for this type of application

  2. #28
    Join Date
    Jan 2010
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    6,838
    Measure your temp at the TXV bulb. Mreasure your suction pressure at the evaporator if possible.
    Convert pressure to temp with P/T chart and adjust the TXV for 4-6 * superheat.

  3. #29
    Join Date
    Dec 2009
    Location
    northeast pa
    Posts
    118
    I wouldn't adjust txv but by charge not touching the txv 7 to 10 at evap 20 at compressor and 3 to 6 subcool

  4. #30
    Join Date
    Aug 2006
    Location
    st.petersburg,fl
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    806

    Lightbulb

    Just a little addition.... That 4-6* SH is measured with box at or close to temp...
    Isn't sanity just a one-trick pony anyway? I mean, all you get is that one trick, rational thinking, but when you're good and crazy, well, the sky's the limit!

  5. #31
    Join Date
    Jan 2010
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    Quote Originally Posted by tech93 View Post
    I wouldn't adjust txv but by charge not touching the txv 7 to 10 at evap 20 at compressor and 3 to 6 subcool
    7-10 would be wasting capacity in the coil. Those numbers work well for a w/i cooler though. And forget about subcooling on refrigeration it is what it is.

  6. #32
    Join Date
    Aug 2006
    Location
    st.petersburg,fl
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    806

    Lightbulb

    Subooling is what it is on a reciever system... measurment means nothing... stick to super heat... Pump system down and watch high side pressure gauge, if neesle rises more than 5 psi you are over chargeed. Or as stated before you can fully pump down system and check reciever level with torch...
    Also Are you certain there is no head master valve, I think you are missing something, cause it sounds like you have one and its stuck in bypass...

    Hope this Helps...
    Isn't sanity just a one-trick pony anyway? I mean, all you get is that one trick, rational thinking, but when you're good and crazy, well, the sky's the limit!

  7. #33
    Join Date
    Dec 2009
    Location
    northeast pa
    Posts
    118
    you are maintaining 0 degrees not -degrees.If superheat is that low it will cause humidity to freeze coil if door keeps opening.cause coil to freeze.reach-ins are the same.If you running those superheat your compressor should be kick off

  8. #34
    Join Date
    Jan 2010
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    6,838
    Quote Originally Posted by skpkey9 View Post
    Subooling is what it is on a reciever system... measurment means nothing... stick to super heat... Pump system down and watch high side pressure gauge, if neesle rises more than 5 psi you are over chargeed. Or as stated before you can fully pump down system and check reciever level with torch...
    Also Are you certain there is no head master valve, I think you are missing something, cause it sounds like you have one and its stuck in bypass...

    Hope this Helps...
    Last winter I installed a outdoor RDI condensing unit. Customer supplied the unit. I was not impressed at all. No head pressure control just fan cycling Then get this. Suction side was capped off but there was no way to access it. Now for the fun part. This unit comes pre charged with refrigerant. So all I could do was valve off the service valve at the compressor and cut the cap off slowly. Then I had to install a service port. OH it gets better yet. When I opened the service valve to vac it down refrigerant form the highside was bleeding threw. All tech support said was we fixed that problem.

  9. #35
    Join Date
    Jan 2010
    Posts
    6,838
    Quote Originally Posted by tech93 View Post
    you are maintaining 0 degrees not -degrees.If superheat is that low it will cause humidity to freeze coil if door keeps opening.cause coil to freeze.reach-ins are the same.If you running those superheat your compressor should be kick off

    Don't confuse superheat with saturated suction temperature.

  10. #36
    Join Date
    Aug 2006
    Location
    st.petersburg,fl
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    806

    Lightbulb

    WOW!!!! You've gotta me kidding me...

    I've worked on RDI systems, never installed them tho... and after reading your post I will steer clear of installing them...
    Isn't sanity just a one-trick pony anyway? I mean, all you get is that one trick, rational thinking, but when you're good and crazy, well, the sky's the limit!

  11. #37
    Join Date
    Dec 2009
    Location
    northeast pa
    Posts
    118
    All product must be frozen before it is store 0 degree freezer won't refreeze product.Most walk-ins have recievers.sounds like to much load in walk-in.

  12. #38
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    Aug 2006
    Location
    st.petersburg,fl
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    806

    Lightbulb

    tech93 - Depending on how the W/I is sized it can and will refreeze product, even tho not good food practices for sake of argument it will refreeze product will just take longer to achieve...Don't know where you got your information but incorrect...

    Hope this helps...
    Isn't sanity just a one-trick pony anyway? I mean, all you get is that one trick, rational thinking, but when you're good and crazy, well, the sky's the limit!

  13. #39
    Join Date
    Sep 2008
    Location
    Western PA
    Posts
    25,946
    Wow, I guess I shouldn't have gone to bed early last night

    My reasoning for the torching is to prove where the liquid level is. Now, I don't know how big this unit is, but I would suspect it should take recovering more than 2 pounds to cause the SG to start bubbling on a 98 degree day. The receiver should have the full flooding charge in it, so unless it is a very small unit, 2 pounds isn't a lot.

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