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  1. #1
    Join Date
    Oct 2011
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    Upstate NY
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    55

    Pressurizing R-123 chillers

    I'm currently performing annual maintenance on a CVHE080. I have had trouble in the past pressurizing these machines, so i've isolated both bundles and i'm circulating hot water thru both the condenser AND evaporator. Water temp currently at 130F & (pull out ur P/Ts fellas) & the actual GUAGE pressure reading is approx. 1.5psi. The UCP2 interface sat. evap temp reading is 91F, which is pretty close to my gauge reading. Pressure in the machine right now should be well above what I'm currently seeing. I'm going to eliminate the obvious and tell you that both tube bundles are CLEAN. I've had this same problem with many other Tranes in the past & attributed it the R-123, but I've pressurized many YT's (some well over a 1000 tons) and had no problems. Anyone else ever have this problem on the Trane machines? Any theories as to why?

  2. #2
    Join Date
    Mar 2004
    Location
    ottawa canada
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    2,091
    Whats the mechanical room temp ?
    Drain the condenser bundle and about a 1/3 of the evaporater and try again , you should have no problem .
    Ps .If its not purging and the chiller does get some off time to equalize in a vacuum (chance to suck in air ) chances are its not leaking and all your doing by heating it up is stressing the chiller and creating leaks . JMHO
    And if shes purging , go over all the flat gaskets with a set of wrenches and you will probably fix it .
    The toy chest is officially full ... I got a new toy..... 2007 Aston Martin V8 Vantage
    You bend em" I"ll mend em" !!!!!!!
    I"m not a service tech.. I"m a thermodynamic transfer analyst & strategic system sustainability specialist
    Best Austin Healey In Show twice in 2013 .....All those hrs paid off .

  3. #3
    Join Date
    Dec 2003
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    45th Parallel
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    957
    Lots of reasons, 1. depends on vintage of machine, newer ones use less refrig. Less refrig to cover tubes when it migrates to other areas.
    2. room temp, lower ambient causes refrig to cond in Comp. 3 stage/more room to hold liquid in the casings
    3. econo also holds a bunch of refrig.

    1.5# isn't bad though. I've had CVHF/E's I could barely get to 0#.
    You might try circulating through only one pass on the evap, and draining the cond barrel. That helps sometimes.
    If you mech room is below 70 deg you might be screwed.
    That is why I quit using a boiler. To hard to get pressure up. I go by purge time and if a leak is suspected that can't be resolved by tightening all the normal leak spots, then pull the gas and use nitrogen.
    Probably going to have to pull the gas anyway to fix leak.
    “If your work speaks for itself, don't interrupt.” ~Henry J. Kaiser

  4. #4
    Join Date
    Mar 2007
    Posts
    3,124
    I see no reason to circulate hot water through the condenser. All the liquid is in the evaporator when the machine is off. Even if you chase it into the compressor, there's nothing you can do about it. Healey Nut is right on about draining the evaporator down to about 1/3 to 1/2, although it is not necessary at least 75% of the time. I have used domestic hot water, gas, and electric units to pressurize chillers and I've never had too much trouble getting them to the 5-7# range.
    "There is no greater inequality than the equal treatment of unequals."

    -Thomas Jefferson

  5. #5
    Join Date
    Aug 2006
    Location
    Mixing oil and fire with a big spoon.
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    4,482
    how many passes in the evaporator? if it is more than 2, are you on the bottom pass? you should also connect a hose between the 2 valves on the economizer to drain the liquid back to the evaporator.

    if you do all of this and you can't get it up, may I suggest Cialis?

    or

    you are low on charge...no liquid refrigerant = no pressure. how oversized is the chiller?
    "If you pull one more stunt like you just pulled with Tommy, you won't have to get on a plane because I will personally kick your ass from here to Korea!" - Best of the Best

  6. #6
    Join Date
    Aug 2009
    Location
    Prattville, Alabama
    Posts
    2,119
    If the purge condensing unit is running, stop it. That little refrigeration unit is cooling the chiller refrigerant and removing the heat that you're adding. I too like to drain the condenser. The water in it is just more mass to heat. And regardless of how many passes the evaporator has, make sure you're using connections for your heater at the bottom of the water head(s) or pipes - otherwise your water flow may be only in the upper tubes, above the liquid level.

  7. #7
    Join Date
    Aug 2006
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    Mixing oil and fire with a big spoon.
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    4,482
    Quote Originally Posted by Nuclrchiller View Post
    ...make sure you're using connections for your heater at the bottom of the water head(s) or pipes - otherwise your water flow may be only in the upper tubes, above the liquid level.
    that too! i just had a newbie learn that the hard way this past winter.
    "If you pull one more stunt like you just pulled with Tommy, you won't have to get on a plane because I will personally kick your ass from here to Korea!" - Best of the Best

  8. #8
    Join Date
    Mar 2004
    Location
    ottawa canada
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    Good idea to make sure you hooked up to the in and out header as well not the return header if its a two pass chiller .
    The toy chest is officially full ... I got a new toy..... 2007 Aston Martin V8 Vantage
    You bend em" I"ll mend em" !!!!!!!
    I"m not a service tech.. I"m a thermodynamic transfer analyst & strategic system sustainability specialist
    Best Austin Healey In Show twice in 2013 .....All those hrs paid off .

  9. #9
    Join Date
    Oct 2011
    Location
    Upstate NY
    Posts
    55
      1. Mechanical room temp 72F
      2. UCP2 vintage machine, 1998 manuf. date, before evap. shell re-design
      3. Purge OFF.
      4. Heater connections at BOTTOM of 2 pass evaporator at nozzle end of shell.
      5. Upon your advice Jay, connected a manifold set from econ. drain valves to the evaporator and increased pressure to 2.5#s max (Didn't want to go above 130 H2O temp)
      6. 1 month script for Cialis, no help (at least not for the machine! )
      7. Machine had 3-4 degree evap approach at full load end of last yr (2 degree on start-up log) so I wouldn't suspect low charge...
    I agree with you DW, I am a "If it ain't broke, don't fix it" kinda guy. Provided the purge is working properly and machine has little or no pumpout time throughout last season, why leakcheck? You were right Graham, leakchecked at 2.5# and found cond/econ flange leaking. Torqued bolts, no more leak. My logic behind heating the cond water as well, was to stave off migration from the evap. I like the idea of draining the cond and heating a partially drained evap, should heat the smaller volume of water faster and only heat the section of machine where the liquid "is supposed to be/stay", I'll try that the next time around. I STILL think these machines can be a PITA to pressurize. As i said in the first post, I've not had these problems with the YT's. I suspect migration to the econ on the Tranes. I guess I shouldn't be too frustrated, I did find the leak and repaired it. I just get more peace of mind with at least 5#s before leakchecking. Thanks guys...

  10. #10
    Join Date
    Mar 2007
    Posts
    3,124
    I know lots of folks that start going around the machine with their sniffer once it gets slightly positive. I don't like this practice. I don't always get it, but I try for 7-8 psig. Those are the actual pressures most machines are subjected to while they're running. Maybe not on the high side, but definitely on the low side. Differential pressure is what makes a leak, and negative pressure is still pressure. You can miss very small leaks at 5 psig. Lots of small leaks add up to a big leak.
    "There is no greater inequality than the equal treatment of unequals."

    -Thomas Jefferson

  11. #11
    Join Date
    Nov 2004
    Location
    North Florida/South Georgia
    Posts
    997

    I'm stuborn about this, but it works...

    First; always hook the entering & leaving hoses to the entering & leaving pipes. This is not negotiable with me as I've had too many weird things happen to me when I do otherwise.

    Second; run the hot water through the condenser first, then the evaporator. This keeps the refrigerant in the evaporator.

    Third; I try to use the gas heater when possible.

    I'm sure some will find this debatable but after too many hours spinning my wheels, this seems to be the right combination.

    PS: It is also a good practice to have hoses only as long as they need to be. This can be tough but worth the trouble to have several different lengths of hoses to work with.
    All my leon freaked out!

  12. #12
    Join Date
    Aug 2006
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    Mixing oil and fire with a big spoon.
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    Quote Originally Posted by tcy612 View Post
    ...You were right Graham, leakchecked at 2.5# and found cond/econ flange leaking....[/INDENT][/INDENT]
    that is a positive pressure area (depending on your head pressure).

    the most difficult chiller to pressurize for me was a small 320 ton trane that never ran over 50% RLA. the building was always empty and it never ran with more than 1F of evaporator approach, however, it was 50% short of charge. after pulling the charge and using nitrogen and R22 i found the leaks, repaired them and weighed the charge back in...all good since then.
    "If you pull one more stunt like you just pulled with Tommy, you won't have to get on a plane because I will personally kick your ass from here to Korea!" - Best of the Best

  13. #13
    Join Date
    Jan 2009
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    Not in Iran
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    1,107
    ok you guys ready for a laugh.,
    bout 5 years ago., before i had a clue, i had to change the oil on a YT.,
    part of the annual.,
    i valved off the chiller., did not drain any water at all, hooked up a 40 gallon hot water heater, and it took like 12/16 hours to get to like 5*.,
    I WOULD NOT SUGGEST THIS AGAIN!!!
    i did have a pump to help move the flow of water.,
    I did get her done.,
    this was a 600 ton 123 machine.,

    when you guys say gas to heat the water, u guys just talking about a gas hot water heater.,?
    guess this is more efficent because heats the water (hotter and faster)?
    how long does it take normally to raise the pressure in a machine to leak check, assuming that the water in the chiller has been adjusted?
    no signature blast'em man blast'em
    !!!KILL THE TERRORIST!!!

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