Page 1 of 2 12 LastLast
Results 1 to 13 of 14

Hybrid View

  1. #1
    Join Date
    Jul 2005
    Location
    south
    Posts
    588

    Trane cvhf770 eductor

    Walking thru mechanical room of new account with a pair of Tranes and saw ice on evaporator eductor on both machines.
    Any ideas? appears to be returning more refrigerant than oil and bottom of compressor terminal cover sweating.

    I logged machine readings and can post if needed.
    Attached Images Attached Images

  2. #2
    Join Date
    Aug 2009
    Location
    Prattville, Alabama
    Posts
    2,020
    This is normal, if its not insulated.. That line is usually insulated, but I have seen many that are not. That area right there is actually the lowest pressure point on the chiller and will get cold enough to frost over to the point of building up a layer of ice. I've seen a ball of ice as big as a golf ball there. The only problem I've seen from it is it can cause rust to form on the oil tank where the condensate runs down. Like it's started doing on that one.

  3. #3
    Join Date
    Aug 2009
    Location
    Prattville, Alabama
    Posts
    2,020
    I don't believe this is related to the sweating on the compressor terminal cover.

  4. #4
    Join Date
    Aug 2009
    Location
    Prattville, Alabama
    Posts
    2,020
    I used to be concerned that the pressure of the ice buildup could create a problem, but I've never seen that happen.

  5. #5
    Join Date
    Mar 2004
    Location
    ottawa canada
    Posts
    2,042
    It isnt abnormal to see ice build up on the eductors , you need to keep an eye on your oil temp to make sure all that refrigerant isnt dropping the oil temp to low . How many turns open is the service valve on the evap where the eductor is drawing from . You may want to try closing the eductor valve down and see if the chiller loses oil , if it doesnt loose oil close it some more if you can maintain oil level with the eductor closed then close it off completely .
    The 64 roars to life Whoo hoo ...shes a rolling chassis .
    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 .

  6. #6
    Join Date
    Oct 2011
    Location
    Upstate NY
    Posts
    55

    Not uncommom

    When possible, I try to install isolation valves, a sightglass and strainer to be able to see ref flow and protect the eductor from plugging up. I was replacing one of these strainers on a running machine once and decided, out of curiosity, to check the pres on the branch of the eductor... I recorded pressures as low as 24-25in hg. P/T indicates a sat. temp well below 32° with R-123.

  7. #7
    Join Date
    Oct 2011
    Location
    Upstate NY
    Posts
    55
    I don't know what the load profile or the application of Licence to chill's
    Machines are, but I would be concerned about oil loss/return if I closed off the evap return eductor line if the machine ran an extended time under light load... Whats say you Healey??

  8. #8
    Join Date
    Mar 2004
    Location
    ottawa canada
    Posts
    2,042
    Quote Originally Posted by tcy612 View Post
    I don't know what the load profile or the application of Licence to chill's
    Machines are, but I would be concerned about oil loss/return if I closed off the evap return eductor line if the machine ran an extended time under light load... Whats say you Healey??
    Like I said .......
    if you can maintain oil level with the eductor closed then close it off completely .

    And this means under all running conditions .
    The 64 roars to life Whoo hoo ...shes a rolling chassis .
    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
    Mar 2007
    Posts
    3,108
    It's normal for some machines, but it can also mean that the strainer is blocked. I don't have any that I have closed off completely like Graham said, although that is what the factory says "If you can maintain the oil level with it closed, keep it closed". I keep the valve open between 1/4 and 1 turn. If I can get away with 1/4, I think this is better. I think all machines lose oil, and oil loss is usually a matter of a lack of oil return. I suspect that more oil is lost through the vent line than most people think. The suction cover eductor is very important also. Every centravac since the early to mid 80s has a suction cover eductor, but not all of them have evaporator eductors.
    "There is no greater inequality than the equal treatment of unequals."

    -Thomas Jefferson

  10. #10
    Join Date
    Jan 2005
    Location
    Houston TX
    Posts
    874
    The eductor problem is solved, now about the sweating of the motor terminal box. There should be about an inch, to inch and a quarter of insulation on all 4 sides of the interior of the motor terminal housing sheet metal. The motor terminal plate should not need insulation as it has a low heat transfer rate, unless Trane in their infinite wisdom has gone to a metal plate instead of the material they were using. I know during annuals I find myself repairing the insulation on the inside of the terminal box and also the area around the outside of the motor, temp sensors box and motor information plate. That solves the sweating problem. -GEO
    Once in a while everything falls into place and I am able to move forward, most of the time it just falls all over the place and I can't go anywhere-GEO

  11. #11
    Join Date
    Aug 2009
    Location
    Prattville, Alabama
    Posts
    2,020
    There was a service bulletin concerning motor terminal box sweating. It involved adding a heater inside the box and how to wire it up. I never did that, so i don't recall any details. Maybe one the guys here can help with that. Also, regarding GEO's mentioning of insulation, even though he did not suggest insulating the motor terminal plate, if this is a 2300V or higher machine, do not insulate the plate. The glue can possibly create a current path. At least that's what a coworker was told once by tech support in LaCrosse. After a burnout. On a chiller with the terminal plate insulated.

  12. #12
    Join Date
    Jul 2005
    Location
    south
    Posts
    588
    thanks for the replys.
    Oil level in tank normal with no foam and oil temp. also normal.
    service valve on evaporator opened 3/4 turn.

    i guess i will keep an eye on it.
    chillers are 4160 volt so i could not take terminal cover off without plant electrician present to see how much condensation if any is inside

  13. #13
    Join Date
    Mar 2004
    Location
    ottawa canada
    Posts
    2,042
    Quote Originally Posted by licensed to chill View Post
    thanks for the replys.
    Oil level in tank normal with no foam and oil temp. also normal.
    service valve on evaporator opened 3/4 turn.

    i guess i will keep an eye on it.
    chillers are 4160 volt so i could not take terminal cover off without plant electrician present to see how much condensation if any is inside
    The 4160V duplex I look after doesnt have insulated terminal boxes but it does have a couple of small 110v resistance heaters in the box instead .
    The 64 roars to life Whoo hoo ...shes a rolling chassis .
    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 .

Page 1 of 2 12 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Comfortech Show Promo Image

Related Forums

Plumbing Talks | Contractor Magazine
Forums | Electrical Construction & Maintenance (EC&M) Magazine
Comfortech365 Virtual Event