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  1. #66
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    Feb 2010
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    keep the vent valve closed

  2. #67
    Join Date
    Mar 2007
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    If migration due to water flow or the room's temperature control is the issue, maybe isolation valves or a different thermostat setting are the answer...?
    The key to happiness is lower expectations.

    Don't pick the fly crap out of the pepper.

  3. #68
    Join Date
    Aug 2004
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    DFW
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    Do you have condensor water regulating valves controlled by the ch530? Maybe settings are different between the 2 machines. Could it be that the chiller having the issue is starting up under different conditions than the other? If the condensor water regulating valve is N.O. vs N.C in the off state. All the rthds I have started up since 2009 have had this valve. I was thinking that they made this required.

  4. #69
    Join Date
    Aug 2004
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    Quote Originally Posted by servicetrane View Post
    keep the vent valve closed
    Say What?
    The valve is closed during shipping. It is opened at start up.

  5. #70
    Join Date
    Oct 2006
    Location
    Central Texas
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    Quote Originally Posted by svc View Post
    Do you have condensor water regulating valves controlled by the ch530? Maybe settings are different between the 2 machines. Could it be that the chiller having the issue is starting up under different conditions than the other? If the condensor water regulating valve is N.O. vs N.C in the off state. All the rthds I have started up since 2009 have had this valve. I was thinking that they made this required.
    I've only heard of the regulating valve as an option, same as the RTHC.
    Sic Semper Tyrannis.

  6. #71
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    Aug 2004
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    DFW
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    I looked it up. You are right it is in option! However it would be a requirement under certain conditions for the chiller to operate within its design envelope. RTHD chillers rely on differential pressure between the compressor discharge and suction to move oil through the compressor rotors and bearings for cooling and lubrication. It also requires an oil pressure differential in order to load the compressor. Lower temperature and pressure in the condenser (and higher temperature and pressure in the evaporator) can reduce the chiller’s differential pressure below the minimum required for proper cooling, lubrication, and loading. The chiller is protected from compressor damage by the CH530 control system. However, inadequate pressure differential will keep the chiller from operating. The most effective way to maintain the required differential pressure during chiller startup and operation is to apply condenser water temperature control.

  7. #72
    Join Date
    Oct 2006
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    Central Texas
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    Quote Originally Posted by svc View Post
    I looked it up. You are right it is in option! However it would be a requirement under certain conditions for the chiller to operate within its design envelope. RTHD chillers rely on differential pressure between the compressor discharge and suction to move oil through the compressor rotors and bearings for cooling and lubrication. It also requires an oil pressure differential in order to load the compressor. Lower temperature and pressure in the condenser (and higher temperature and pressure in the evaporator) can reduce the chiller’s differential pressure below the minimum required for proper cooling, lubrication, and loading. The chiller is protected from compressor damage by the CH530 control system. However, inadequate pressure differential will keep the chiller from operating. The most effective way to maintain the required differential pressure during chiller startup and operation is to apply condenser water temperature control.
    Agreed 100%. The Carrier 30HXCs are the same way, the machine is not sold with a regulating valve, but one can be field installed, set-up, & the chiller will control the valve. People really need to have to have good control of their towers w/ these machines.
    Sic Semper Tyrannis.

  8. #73
    Join Date
    Mar 2010
    Location
    Va.
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    Trane recomends controling the condenser bypass based on the pressure difference between the condenser and evaporator. A minimum of 23# delt-p between the condenser and evaporator needs to be maintained for proper oil flow. The condenser water needs to be 17deg higher than the chill water with in 2 min of startup. A 25deg. deta-t must be maintained.
    Attached Files Attached Files

  9. #74
    Join Date
    Oct 2010
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    2
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    try setting your delta P to 240kpa (2vdc) min and 480kpa (10vdc) max for your cond regulating valve

  10. #75
    Join Date
    Jan 2009
    Location
    Not in Iran
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    control

    yep., there are 5 reasons why this machine need this control
    and 4 methods of control.

    no signature blast'em man blast'em
    !!!KILL THE TERRORIST!!!

  11. #76
    Join Date
    Oct 2007
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    knoxvegas
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    How do you "pump" the oil out of the bottom of the evap to the oil sump?

    Quote Originally Posted by servicetech 32 View Post
    I have two RTHD chillers in the same plant. One has problems with loss of oil about twice a year. The other has never had a problem. The gas pump always checks out fine using the discharge superheat method. The original installer could not figure it out. Local Trane techs have looked at it several times and say they are stumped as well.

    I thought that I fixed the problem a couple years ago when I replaced the master oil solenoid. When the machine shuts down you can hear oil flow through the oil sump if you carefully put your ear to it. If you close one of the ball valves on the oil feed line the sound stops. Open valve sound starts again. Seemed like the solenoid was leaking by. Discharge pressure would push oil out of the sump and into the compressor. Replaced the solenoid. Sound was still there but seemed better and ran for a year or two without a problem. Anybody else notice the oil flow sound after shutdown? Any other explanation other than oil flow?

    I will request the service bulletin on Monday as a Google search did not reveal anything helpfull. Figured we would just have to live with this problem.

    The oil and refrigerant charge are all correct. A really good tech from the factory pulled both when he changed out the liquid level sensor and weighed all back in. I always pump the bottom of the evaporator into the oil sump to return the oil.
    Just how do you get the oil back to the sump once its lost to the evap? Use a magnet to open the drain solenoid? until llid reads wet in sump? What if pressures are pretty much equal? Can you cycle open the CW valve to get lower loop temp to create differential?
    THanks
    Ken

  12. #77
    Join Date
    May 2008
    Location
    Central Pennsylvania
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    Quote Originally Posted by corwin401 View Post
    Just how do you get the oil back to the sump once its lost to the evap? Use a magnet to open the drain solenoid? until llid reads wet in sump? What if pressures are pretty much equal? Can you cycle open the CW valve to get lower loop temp to create differential?
    THanks
    Ken
    Look at post #60 of this thread for the answer to your question.

  13. #78
    Join Date
    Oct 2007
    Location
    knoxvegas
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    There was some oil loss on the two oil solenoids that I changed out, so I shut the discharge oil filter ball valve and added about 1/3 of a gallon of new oil. added another 1/3 after wet indication came back on. Let it warm up overnight and It did just fine the following day. This is the second RTHD 2009 that Ive had both oil solenoids leaking from the top, like someone used a can opener on them. I've seen the 2003 bulletin that said they "got rid of those valves and since then have had no problems." Now why did they make a confidential SB that said pretty much the same thing except for dates? (and also paid for the parts and some labor.) It looks like they really didn't get rid of the "bad" solenoid valves just slowly put them back in the system. I find it odd that my customer is out a ton of cash for refrigerant and parts that should have never been put in in the first place. In over 30 years of commercial service, I have yet to see this kind of failure, nor can I find any other seasoned tech to say the same. But anyway they are both working fine except for some more refrigerant to bring up the charges before summer.

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