TXV overfeeding
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Thread: TXV overfeeding

  1. #1
    Join Date
    Jun 2012
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    1

    TXV overfeeding

    I replaced a 26ton sporland TXV with a new emerson 26 ton valve ...Original symptoms low superheat, low suction, coil has been chemically cleaned Air flow good 12deg sub cool clear sight glass.......same symptom after un able to adjust.

  2. #2
    Join Date
    Jun 2008
    Location
    Rochester, NY
    Posts
    61
    It could be loose bulb connection or poor bulb placement. Make sure the bulb is well insulated.

    Is the txv adjustable?

  3. #3
    Join Date
    Feb 2010
    Location
    In a boiler room
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    7,043
    Well, low SH and low suction pressure does not indicate a txv problem.

    It means you have low load. Verify correct evaporator airflow.

    What make and model unit?

  4. #4
    Join Date
    Apr 2012
    Posts
    6
    Location of Sensing bulb? Insulation around bulb?

  5. #5
    Join Date
    Apr 2012
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    Paper Street Soap Company
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    That doesnt sound like a bad TXV.

    Whats the delta across the coil ? TXV failure is actually pretty rare. Power head maybe but not the valve.

    Sounds like low air flow. Coil cozld be clean but it might have an adjustable shiv on it.

  6. #6
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,699
    Air flow good? How many CFM is that?

    What was your delta across the indoor coil? 16, 20, 26?

    What was the outdoor temp?
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  7. #7
    Join Date
    May 2003
    Location
    Utah
    Posts
    718
    While it's a pain to check, this sounds like a classic case of an oversized distributor nozzle. If there's too little pressure drop through the nozzle the liquid and vapor will not properly mix, causing the lower circuits to receive too much liquid (resulting in the low superheat) and the higher circuits receive too little liquid (resulting in low load).

  8. #8
    Join Date
    Jun 2012
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    Northern NV
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    154
    Or could be the orifice in the distributor is MIA........

  9. #9
    Join Date
    Apr 2012
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    Quote Originally Posted by bunny View Post
    While it's a pain to check, this sounds like a classic case of an oversized distributor nozzle. If there's too little pressure drop through the nozzle the liquid and vapor will not properly mix, causing the lower circuits to receive too much liquid (resulting in the low superheat) and the higher circuits receive too little liquid (resulting in low load).
    he just replaced the valve.

    you think it never had the correct orrifice in it ?

  10. #10
    Join Date
    Jun 2012
    Location
    Northern NV
    Posts
    154
    ....or someone thought it would "improve" the performance if the restriction to flow was gone?

    Do you always check for the presence of the restrictor in the distributor? Or do you (as I have) take it for granted that it was there and correct for the equipment... Just as I don't expect that the previous tech was twiddling with the superheat adjustment to correct an airflow issue. Anymore, I have learned that if it has been "serviced" the all bets are off the table on what you might find.

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