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  1. #1
    Join Date
    Apr 2011
    Location
    West of DFW
    Posts
    240

    Traulsen TXV adjustment

    I had a call for a reach in freezer that was not working. After thawing out the evap coil. I noticed the txv had been messed with(Cap was off and on skid). I recoverd the "juice" checked to see where the txv was adjusted to. It was opened up all the way. I then counted the revolutions open to closed. It was 8. So mid seated the adjustment to around 4. Pulled a good vacume and weighed in 20 oz. I am now checking superheat. What do you think?

  2. #2
    Join Date
    Sep 2007
    Location
    NH
    Posts
    1,146
    So whats the SH??? And SC???

  3. #3
    Join Date
    Apr 2011
    Location
    West of DFW
    Posts
    240
    SH is down to 20 last checked this morning. Didn't get a chance to get back to it this afternoon. Freezer temp -10 f.

    Low side:-20 saturation. PSIG?
    I'm trying to go off of memory (not working)
    All the parameters for the intellitrol were great.
    Defrost cut in/out -10 to 9 F
    Termination temp. 45 F

  4. #4
    Join Date
    Jan 2010
    Posts
    6,206
    20* SH sounds pretty high for a freezer. Where are you checking your SH ?

  5. #5
    Join Date
    Apr 2011
    Location
    West of DFW
    Posts
    240
    Yes sir that's high. I'm checking right out of the evaporator cabinet.

  6. #6
    Join Date
    Apr 2011
    Location
    West of DFW
    Posts
    240
    I'm looking for 7 to 9 SH. I'll check it all out tomorrow and post the prudent info. needed. It's been busy.

  7. #7
    Join Date
    Jan 2010
    Posts
    6,206
    Quote Originally Posted by blazey10 View Post
    I'm looking for 7 to 9 SH. I'll check it all out tomorrow and post the prudent info. needed. It's been busy.
    You could go as low as 4 and be safe from flood back.

  8. #8
    Join Date
    Jan 2006
    Location
    DFW Metroplex
    Posts
    4,910
    Quote Originally Posted by VTP99 View Post
    You could go as low as 4 and be safe from flood back.




    Ya know, we may have gotten off on the wrong foot......you don't seem to be half bad after all.
    "The problem is the average person isnt tuned in to lifelong learning, or going to seminars and so forth. If the information is not on television, and its not in the movies they watch, and its not in the few books that they buy, they dont get it" - Jack Canfield

  9. #9
    Join Date
    Feb 2008
    Location
    California
    Posts
    2,065
    Since this is a self contained unit with probaly a very short suction run to the compressor. It will also be a good idea to check compressor superheat. Most manufactures are going to recommend not too much lower than 20* superheat at the compressor.

    On these small systems compressor superheat will trump evap coil superheat.

    A nice efficient evap coil doesn't mean much when a compressors drinking liquid.

  10. #10
    Join Date
    Jun 2009
    Location
    DFW, TX
    Posts
    661
    Seeing as how the evaporator cabinet is about 12 inches away from the compressor, I don't think 20 degrees of superheat is high. I think its perfect.

  11. #11
    Join Date
    Apr 2011
    Location
    West of DFW
    Posts
    240
    intel-a-traul temp. is -14F
    Liquid line temp. 92
    Liquid Sat. 94
    High side 220 PSIG
    Low Side 10 PSIG
    Low side line temp. 21

    Recap: TXV was wide open. I mid stroked the adjustment(halfway between open and closed) Weighed in new charge. This is where I am at now. I suppose TXV was opened up all the way by another tech to lower superheat, or is thought wrong? Now I'm confused.

  12. #12
    Join Date
    Jun 2006
    Posts
    203
    how much refrigerant was recovered? was it under or over your 20 oz ?

  13. #13
    Join Date
    Jan 2006
    Location
    DFW Metroplex
    Posts
    4,910
    Quote Originally Posted by blazey10 View Post
    I had a call for a reach in freezer that was not working. After thawing out the evap coil. I noticed the txv had been messed with(Cap was off and on skid). I recoverd the "juice" checked to see where the txv was adjusted to. It was opened up all the way. I then counted the revolutions open to closed. It was 8. So mid seated the adjustment to around 4. Pulled a good vacume and weighed in 20 oz. I am now checking superheat. What do you think?
    Quote Originally Posted by blazey10 View Post
    intel-a-traul temp. is -14F
    Liquid line temp. 92
    Liquid Sat. 94
    High side 220 PSIG
    Low Side 10 PSIG
    Low side line temp. 21

    Recap: TXV was wide open. I mid stroked the adjustment(halfway between open and closed) Weighed in new charge. This is where I am at now. I suppose TXV was opened up all the way by another tech to lower superheat, or is thought wrong? Now I'm confused.
    So am I.

    When you said the reach in freezer was not working, what did you mean, precisely?

    Was the compressor not running?
    Was the compressor running, but kicking out intermittently?
    Was the compressor running continuously but not maintaining case temp?
    Was the evap coil iced up?
    Were the evap fans running?
    Was the system stuck in defrost?

    "Not Working" is such a vague term. It's hard to offer advice when the only thing we know is the freezer was not working - you pulled the gas - tweaked the valve - and added gas.

    Why did you feel it was necessary to pull the gas? What was the unit doing (or not doing) that made you feel it was necessary to throttle the TXV closed so far?

    Based on your latest post (and I'm making an assumption on R404A being used), your low side pressure was 10 psig and your suction temp (again, I'm making an assumption it was at the outlet of the coil) was +21F.

    By my calculations, the unit is running at about +51F superheat. This is a helluva lot higher superheat than you had indicated yesterday.

    You may have a TXV not functioning properly - but it's hard to tell with the information given.
    "The problem is the average person isnt tuned in to lifelong learning, or going to seminars and so forth. If the information is not on television, and its not in the movies they watch, and its not in the few books that they buy, they dont get it" - Jack Canfield

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