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  1. #1

    McQuay water source heat pump

    I have a McQuay 5 ton water source heat pump above a drop ceiling and surrounded by duct work and sprinkler lines so space is tight and vision poor . This unit was controlled by energy management but has been locking out lately . I disconnected the EMS and jumped the unit out with RED , W-1 and G . the unit turns on in heat for about 5 minutes then the reversing valve screams and it goes to cooling , 5 minutes , the scream and back to heat . The install guys did me no favors as I may have to drop the unit to access the controls . Any idea what this might be before I rip the ceiling out ???

  2. #2
    Join Date
    Sep 2011
    Location
    Vancouver, WA
    Posts
    239
    If this unit has been made recently, you might have a control board with LED's and a legend for reading the fault codes. Other than that you do not give enough information to make an educated guess, no pressures, no temps, is the blower working? Help the people on this site help you by providing all the info you write down on your note pad. I've been doing this for a long time, access is always an issue, I will remove duct work, have sprinkler lines relocated, have any obstruction moved or removed so I can get access to an equipment's control box. How are you going to troubleshoot the problem if the unit is on the ground?

  3. #3
    Join Date
    Sep 2011
    Location
    Souther Cal
    Posts
    10
    Please get pressures while unit is making noise, I had a similar situation and we ended up having the customer keep a spare unit in stock so if the unit needed to be opened up we swapped unit out and repaired it in the shop . We built a test area that had water lines to connect to condensor water. Fan is running ? Restictions in air or refrigerant?

  4. #4
    Join Date
    Sep 2011
    Location
    Vancouver, WA
    Posts
    239
    Quote Originally Posted by Kenoo8 View Post
    Please get pressures while unit is making noise, I had a similar situation and we ended up having the customer keep a spare unit in stock so if the unit needed to be opened up we swapped unit out and repaired it in the shop . We built a test area that had water lines to connect to condensor water. Fan is running ? Restictions in air or refrigerant?
    The problem with pulling a unit off the job and taking it to laboratory setting is what if the problem is related to how it's installed, a failed fire/smoke damper, the condenser water temp or flow? How do you explain to your customer when the problem follows the unit? The unit when installed is part of the building and needs to be serviced in place. Unless the unit has wheels and can be pushed out the back door, it should stay right where it is.

  5. #5

    mcQuay water source heat pump

    This unit has a 103 discharge in heat and a 49 discharge in cool . compressor working fine . the blower is good with no dampers in line . Has anyone ever seen a reversing valve that switched back and forth ? I was thinking the control board is bad , droping the voltage to the reversing valve , but I cannot get to the controls . Just hoping for a good educated guess before I rip the ceiling apart .

  6. #6
    Join Date
    Oct 2011
    Location
    Las Vegas, NV
    Posts
    458
    Check that all of your low voltage wiring is tight and that you don't have a loose connection. You will need to get to the controls and also get your gauges on there to see what it's actually doing. It is not uncommon for those to fail, I've changed a few of them.

  7. #7
    Join Date
    May 2008
    Location
    New Mexico
    Posts
    21
    The reversing valve coil might be going out/ohm it out/
    question can you use a megger on it?
    Good Luck getting to the controls

  8. #8
    Join Date
    Aug 2008
    Location
    S. Grand Prairie
    Posts
    244
    Quote Originally Posted by NRG$WIZ View Post
    The reversing valve coil might be going out/ohm it out
    ...i'd check this also...
    Originally Posted by ladyfire3374:

    "I used to wake up excited about the challenges of the day. Now the anticipation level is somewhere between a root canal and a colonoscopy."

  9. #9
    Join Date
    Nov 2011
    Location
    Texas
    Posts
    233
    Quote Originally Posted by NRG$WIZ View Post
    The reversing valve coil might be going out/ohm it out/
    question can you use a megger on it?
    Good Luck getting to the controls
    I would also check the coil on reversing valve, also take the wires off your valve and see if your dropping 24v

  10. #10
    Join Date
    Mar 2001
    Posts
    1,454
    faulty defrost control?
    One way to outthink people is to make them think you think. They'll think you're not really thinking what you're trying to get them to think you think...........

  11. #11
    Join Date
    Jul 2011
    Location
    indiana
    Posts
    60
    Check the LED codes if yoi jave mark 4 board or any other board, water flow is very important in units like this ,strainers might be pluged and if you take it upart you will be amazed whats in there, good luck

  12. #12
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    33,375
    Quote Originally Posted by uniservice View Post
    faulty defrost control?
    Uh, if you need a defrost control on a WSHP, something fishy

  13. #13
    Join Date
    May 2004
    Location
    SE Pennsylvania
    Posts
    829
    Run the unit in what ever mode that does not require the revering valve to energized and unwire it to eliminate the coil as a problem. 103 head in heat, 49 in cool, typo I hope?

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