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  1. #1
    Join Date
    Feb 2007
    Location
    vermont
    Posts
    12

    horizontal compressor question

    Hello , first post in along time. I worki asmall hotel heated and cooled by water source heat pumps, mostly Mcqyay and Mammoth. alot of our younger units (2-5 years old) use horizontal tecumseh's that are failing at an unusually high rate compared to the vertical ones. has any one else experienced this? any thoughts? the only thing that I have noticed is that when cutting out the failed compressors there is alot of oil everywhere including the reversing valves (basically full of oil). Thanks, pipes

  2. #2
    Join Date
    Dec 2010
    Location
    Florida
    Posts
    34
    What are the failures?

  3. #3
    Join Date
    Feb 2007
    Location
    vermont
    Posts
    12
    compressor burnout (due to revesing valve failure?)

  4. #4
    Join Date
    Dec 2010
    Location
    Florida
    Posts
    34
    Quote Originally Posted by pipes6 View Post
    compressor burnout (due to revesing valve failure?)
    Do they reverse in cool or heat?
    Have you tested the water flow?
    Where and how is it getting water?
    Is water Constant flow?
    What is water Temp?
    What kind of Control (Stat)?
    Verify Voltage? Single Phase or Three?
    Check Multi Volt Transformer on correct Voltage?
    Are all failures dut to Reversing Valves?

  5. #5
    Join Date
    Feb 2007
    Location
    vermont
    Posts
    12
    both modes, Mammoth's energize to cool, Mcquays energize to heat. after acouple ofyears, sometimes less get call for no heat/cool and find comp running but not much happening generally low delta T on both coils low suction and head. have recovered and weighed in fresh charge with no change(prior to complete failure), not low on charge. superheat generally 50* +, felt one the otherday that was hot on suction line (105*) thats what gotme thinking reversing valve oil logged

  6. #6
    Join Date
    Feb 2007
    Location
    vermont
    Posts
    12

    Post

    both modes, Mammoth's energize to cool, Mcquays energize to heat. after acouple ofyears, sometimes less get call for no heat/cool and find comp running but not much happening generally low delta T on both coils low suction and head. have recovered and weighed in fresh charge with no change(prior to complete failure), not low on charge. superheat generally 50* +, felt one the otherday that was hot on suction line (105*) thats what got me thinking reversing valve oil logged. Water loop runs about 80*, have checked flow(timed bucket) have flushed water coils. voltage is 208 single phase low voltage is good. these unit seem to run OK for about 2 years then start having problems. ruling out the usual suspects ie; obstructions, filters, idiots screwing with the thermostat etc. and having the same type of problems with multiple units from different manufacturers that share the same type of failures with the same comps ( mostly tecumseh HGA5512EXD) I am out of ideas, the only unusual thing I have found is unusual amounts of oil when opened up to replace comp/reversing valve. The last time i replaced a comp I changed to en RKA5512EXD, time will tell(had to cut a hole in the top cover). Just wanted to see if others are having similar problems. sorry to be so long winded. pipes

  7. #7
    Join Date
    Dec 2010
    Location
    Florida
    Posts
    34
    Need more
    TXV= Sub Cooling? TXV, TXV, TXV
    Fixed= Super heat
    Water Temp out?
    50 Degree super heat! What are your Pressures
    Water out Temp?
    Have the S Coils been changed? Incorrect piping?

  8. #8
    Join Date
    Mar 2003
    Posts
    7,314
    one manufacturer has an auto reset low pressure switch, which trips due to the compressors being slightly oversized for those small heatpumps. Water flow needs tobe right, and bidirectional regulating valve must be set right. There is a service bulletin that came out to install a low pressure bypass timer, to allow the compressor system ot equalize prior to enabling the cutout, thereby preventing the short cycling that occurred. The short cycling was killing the compressors.

  9. #9
    Join Date
    Apr 2012
    Location
    So. Fl.
    Posts
    57
    Try installing variable time delay (10 min.)at compressor contractor coil,then some tattletes on a test Unit(older model)just to what it may have tripped out on. You can also start checking for proper Spht/subcooling, to make sure refr.side is ok in the IOM.

  10. #10

    Frown Compressors

    Hi, I have 90 of this type of units on my property using the same compressors. I found a problem with the low pressure safety circuit, that was locking up the compressor in a condition of low pressure. Instead of shutting down the unit it will cycle the compressor for a fraction of a second and then the compressor overload shuts it off, because it can't restart after the cycle and locks. Most of my faults were grounded compressors. I had Mammoth pay me to rewire the low pressure safety circuit which includes a time delay and a relay. They did a lab test and agreed that their logic was not working right. I am also looking for a vertical type compressor that will fit the box, i have no room to cut the top open.
    High failure rate on the TXV's, RV. I am in Vegas, so every time I drop a unit for repair, I remove the RV , because we don't need heat here and replace the TXV with piston assemblies that I ordered from Mammoth and charge it based on the SH, SC method.

    I hope that will help you

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