Page 1 of 4 1234 LastLast
Results 1 to 13 of 43

Thread: Trane CVHE

  1. #1
    Join Date
    Apr 2005
    Posts
    517

    Trane CVHE

    What causes low end surge with Trane centravacs?

  2. #2
    Join Date
    Feb 2006
    Location
    SouthEastern Virginia
    Posts
    1,075
    low chilled water flow
    It might get loud!

  3. #3
    Join Date
    Dec 2007
    Location
    peoria,il.
    Posts
    7
    Light load, low water flow, vane adjustment. These are where you may want to start.

  4. #4
    Join Date
    Apr 2005
    Posts
    517
    Can you explain whats going on inside the machine during low end surge?

  5. #5
    Join Date
    Mar 2004
    Location
    ottawa canada
    Posts
    2,065
    Its all about the lift ---- too little low end surge, too much high end surge.

  6. #6
    Join Date
    Feb 2006
    Location
    SouthEastern Virginia
    Posts
    1,075
    Graham,

    You may need to explain "Lift" and how low end surge affects it.
    It might get loud!

  7. #7
    Join Date
    Mar 2004
    Location
    ottawa canada
    Posts
    2,065
    Sorry its Friday a few too many beers in me . Every chiller has a design lift .That is the difference in pressure between the evap and cond bundles {refrigerant} that pressure has a range of which the chiller has to operate between so it will not surge , to little lift -low end surge , too much -high end surge. Not bad for a Friday even if I say so myself?????

  8. #8
    Join Date
    May 2006
    Location
    Western NY
    Posts
    4,356
    Say you have a centrifugal chiller with R-134a, the condenser pressure at 97* is 118.3 psig. The evap. pressure at 42* is 36.6 psig. Subtract the two and there is the lift the compressor must provide. In this case, 81.7 psig.
    "Excellence is the gradual result of always striving to do better"
    -Pat Riley

  9. #9
    Join Date
    Oct 2006
    Location
    Central Texas
    Posts
    634
    Quote Originally Posted by ej45 View Post
    Can you explain whats going on inside the machine during low end surge?
    Keep in mind there is no difference between a high end surge & low end, in terms of whats happening mechanically to the compressor, it's the same effect. A surge is a surge, it's just a matter of what is causing it. Like the other fellas have said, its all about lift.
    Sic Semper Tyrannis.

  10. #10
    Join Date
    Apr 2005
    Posts
    517
    Is low end surge caused by a deeper pressure between the third stage vane and the first stage compared to condenser pressure? (causing reversal of gas from condenser to between stages) If I remove first stage operator rod and slightly lead the vanes open the surge goes away.

  11. #11
    Join Date
    Mar 2004
    Location
    ottawa canada
    Posts
    2,065
    OK here goes . the compressor has to overcome the difference in pressure between the two vessels ,by leading the the first stage vanes you are allowing more refrigerant into the compressor the compressor now has more push and is able to overcome the difference between the vessels- no more low end surge . In a high end surge the compressor cannot push the gas into the condenser the gas rushes backwards through the compressor causing the squealing pig sound and if it is really bad it will stall the compressor.

  12. #12
    Join Date
    Oct 2006
    Location
    Central Texas
    Posts
    634
    Surging, stalls, etc. Play all kinds of hell on bearings, seals, gears (on some machines) if allowed to continue for a long period of time.
    Sic Semper Tyrannis.

  13. #13
    Join Date
    May 2008
    Location
    Southern California
    Posts
    55
    I think what TX is saying is .... Mo money, Mo money, Mo money.

    Honestly the impeller will not push gas foreward and your machine surges for two reasons:

    First, if the molecules of gas can't catch enough energy from the spinning to jump into the condenser. The back pressure of the condensor versus the suction pressure is too great even if there are plenty of molecules to pick up that energy. The molecules spin around, picking up the energy that the wheel has, but not enough is available for them to overcome the backpressure. They become confused and the more organized (pressurized) ones push back.

    The second case is when the spinning wheel has enough energy to overcome the resistance of the condensor but can't find enough volunteers to share that energy with. The lack of molecules for the wheel to give its energy to becomes the problem. The wheel is trying to draw the molecules into it but there just aren't enough to get organized for the job. Then there becomes a point that the gas (or lack of gas) is no longer getting the amount of energy required to push foreward and blah blah blah....the gas pushes back.

    The things you should always look for is sufficient energy available from the spinning wheel and enough molecules of refrigerant to carry that energy into the the condensor. If you lack one or the other the flow will stop, or go in reverse, untill the correct balance is restored.

    .....or not.

Page 1 of 4 1234 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