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  1. #1
    Join Date
    Feb 2008
    Location
    petaluma,ca
    Posts
    48

    Confused reversing valve trouble, heeeeeeeeeeeeeeeeeeelp!

    I have beeb working on a new EMI 3x multi heat pump. I replaced the reversing valve and operation to the unit was restored, the following month the same thing happens, once again the the valve was replaced and operation was restored, here we are 3 months later and the unit is down again. all repairs were performed with a nitrogen purge, 3 evac, heat paste and a wet wrap on the valve. I have never in 13 years had a revesing valve go out more than once. The only explaination would be a bad batch of valves made at the factory, but those odds are slim. any ideas?

  2. #2
    Join Date
    Aug 2009
    Location
    Beatrice, NE
    Posts
    2,067
    I'm assuming that the valve isn't switching, if that's the case have you tried to get it to move or just replaced?

    I have seen several times where oil gets in the pilot tubes and is what causes the valve to stick. If that's the case why is the oil leaving the the compressor in such large amounts? There are things you can do to help keep the oil out but I would think there would be something causing the oil migration which would need to be resolved.

    The other thing would be debris in the system causinghte valve to stick. If thats the case where is it coming from? Do you have a drier that broke down, are there metel shavings coming from somewhere?

  3. #3
    Join Date
    Nov 2007
    Location
    Mississippi
    Posts
    1,338
    I keep having the same problem with Trane water source heat pumps. Have probably replaced about 12. Some multiple of times on same unit. I just assume its the tubes getting plugged causing this.

  4. #4
    Join Date
    Jun 2011
    Location
    Detroit vicinity, Michigan
    Posts
    79
    Quote Originally Posted by socotech View Post
    I keep having the same problem with Trane water source heat pumps. Have probably replaced about 12. Some multiple of times on same unit. I just assume its the tubes getting plugged causing this.
    Recently picked up 3 new small tonnage valves from Trane. Had a tech covering my account while I was off a week and returned to find he'd been struggling with one unit for that time due to 2 of the 3 valves did not seat and were blowing straight through. When he changed it the second time and had the same results it blew his mind and kept looking for another problem. When I got back I approached the unit as if no work had been done, condemned the valve and told him to change it for a third time, but first I blew through the valve and verified it only came out one port put that one in and it worked finally. Pulled the first one out of the scrap and blew through all 3 ports, same with the second.....lost a ton of hours but hey, Trane gave me two new ones to make up for it.

  5. #5
    Join Date
    Jun 2011
    Location
    Detroit vicinity, Michigan
    Posts
    79
    Quote Originally Posted by kls-ccc View Post
    I'm assuming that the valve isn't switching, if that's the case have you tried to get it to move or just replaced?

    I have seen several times where oil gets in the pilot tubes and is what causes the valve to stick. If that's the case why is the oil leaving the the compressor in such large amounts? There are things you can do to help keep the oil out but I would think there would be something causing the oil migration which would need to be resolved.

    The other thing would be debris in the system causinghte valve to stick. If thats the case where is it coming from? Do you have a drier that broke down, are there metel shavings coming from somewhere?
    Again, careful inspection of the failed valve can tell you why its failing.

    Just replaced one on a McQuay that had a comp burnout and was found stuck after the comp was replaced. Just looking inside the ports I could see black residue, scraped some out and found it gritty......with dessicant. It runs but with low suction in both modes. And this is where it gets weird, no txv, only cap tubes and distributor, McQuay calls it a strainer-distributor but obviously it is a drier also and its coming apart.
    This is a 2 ton unit and the line between the water coil and the distributor is huge, a 7/8 liquid line in cooling mode....
    Before I realized it was a drier I was asking tech support about bushing the line down to accept a bi-flow rated for 2 tons and he told me they just don't put driers on the heat pumps, guys just change out the comp......really? That's your recomendation after a burnout? Well I guess you sell more parts that way....and he laffed.

    All the previous work was done in the ceiling cause the customer doesn't want to pay to drop it down where it can be easily worked on. One bill for the comp, a second bill for the valve, now a third for me to drop the unit, flush it out, change the cap tubes and strainer/drier.....and listen to the piss and moan bout how we should be able to diagnose all this with a dead comp.

    Oh yeah, nice of McQuay to stop producing DC coils for the reversing valves and just ship out an a/c coil with no explanation. Here's the answer if you run across this......powerva RIB relay with the valve leads, grab 24 AC off the trans and run it through the relay to power the new one, not difficult but can cost you some time if you don't have a DC relay on you.

  6. #6
    Join Date
    Feb 2008
    Location
    petaluma,ca
    Posts
    48
    The valve would not switch out of the heating position, when the coil was energized i could hear the pilot valve click, i
    I also confirmed the refrigerant charge was ok. Both valves and refrigerant looked clean. New drier installed with every valve.
    what could cause oil migration?I don't think there are any metal shavings in the unit, unless they were already present when we received the new unit. the indoor coil is no more than 3' higher than the outdoor coil with about a 50' lineset.

    Thanks for the help

  7. #7
    Join Date
    Aug 2009
    Location
    Beatrice, NE
    Posts
    2,067
    Oil migration happens all the time whenthe compressor is running. Things like being overcharged and leaks seem to make it worse.

    Have you tried raising the head pressure, without adding refrigerant to see if it would shift?

  8. #8
    Join Date
    Feb 2008
    Location
    petaluma,ca
    Posts
    48
    Yes I tried closing one of the service valve,but no luck, what if I have too much oilin the compressor? I was thinking about changing the comp oil at the same time as the valve.

  9. #9
    Join Date
    Aug 2009
    Location
    Beatrice, NE
    Posts
    2,067
    Compressor oil shouldn't need to be changed. Closing a service valve won't raise the presssure as needed and could cause a problem if the valve does shift.

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