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  1. #1
    Join Date
    May 2009
    Location
    Canada
    Posts
    38

    water regulating valve piping question

    what are the draw backs of a water regulating valve installed in the outlet of a shell and tube condenser? I have a danfoss WVFX valve on the outlet of this type condenser and the system(12hp) has been working on cooling tower water but now it is tripping on on high head pressure. I can switch to town water and it runs great. I have two water cooled units side by side and they both have the same problem which seems to indicate a problem with the tower(which is cooling various peices of equipment, of which we service neither these nor the tower just the chillers) or a flow problem in the piping?

    the town water is 67*F and 60 psi ...........outlet temp 80*F
    cooling tower water is 74*F and 40 psi..............outlet temp 120*F

    I opened wide the regulating valves for both systems and switched to cooling tower water and it was maintaing at 90*F outlet yesterday , today is cooler and they are 80*F, naturally cooler ambient + lower wet bulb = cooler tower water.

  2. #2
    Join Date
    Feb 2004
    Location
    Western New York
    Posts
    1,049
    While keeping an eye on your head pressure, (BTW, what gas are you using?). I like to watch the discharge temp of the condenser cooling water. If you have full flow and anything much over 105 deg, suspect a dirty condenser.

    Low water flow, combined with scaling could be your problem.

    BTW, Hoshizaki always puts their regulator on the outlet. Their techs have told me that's to keep the condenser fully flooded with water. That is true, but you could get the same effect with a valve on the inlet, and a short riser on the discharge. I like the cooler inlet water hitting the valve, plus there is less chance of scale and crud pieces settling in the valve seat. Small point tho.
    Experience is what you have an hour after you need it.

  3. #3
    Join Date
    Feb 2004
    Location
    Western New York
    Posts
    1,049
    My bad
    Last edited by baub; 07-29-2010 at 06:42 PM. Reason: Double post
    Experience is what you have an hour after you need it.

  4. #4
    Join Date
    Aug 2008
    Location
    Philadelphia
    Posts
    84
    From the information in your post, it sounds like you have a fouled condenser. You are staying online with city water because it is cooler. To really get a picture of what is going on in the system, you will need to take an approach temp. (leaving water vs. liquid line temp). They should be very close in a system that is clean, but will be come very high if there is slime or some other insulation in your tubes. If you are looking for 105 condensing your leaving water should be pretty close to that.

    You might need to break out the acid.
    Do not weep, do not wax indignant. Understand.
    -Spinoza

  5. #5
    Join Date
    Aug 2002
    Location
    Southold.calm
    Posts
    5,689
    Don’t leave out fouled piping on the water out side. Break the union after the valve and run it to a floor drain, if the head pressure settles then there’s problems with the piping.

    I’ve seen 1 ½” return lines closed to less then 3/4”

  6. #6
    Join Date
    May 2009
    Location
    Canada
    Posts
    38
    Quote Originally Posted by pecmsg View Post
    Don’t leave out fouled piping on the water out side. Break the union after the valve and run it to a floor drain, if the head pressure settles then there’s problems with the piping.

    I’ve seen 1 ½” return lines closed to less then 3/4”

    yes, I'm suspicious of pipe restrictions, the plant foreman has said it's been a while since the tower and piping have seen maintenance. thanks for this idea for proving fouled piping.

  7. #7
    Join Date
    May 2009
    Location
    Canada
    Posts
    38
    Quote Originally Posted by bullgear420 View Post
    From the information in your post, it sounds like you have a fouled condenser. You are staying online with city water because it is cooler. To really get a picture of what is going on in the system, you will need to take an approach temp. (leaving water vs. liquid line temp). They should be very close in a system that is clean, but will be come very high if there is slime or some other insulation in your tubes. If you are looking for 105 condensing your leaving water should be pretty close to that.

    You might need to break out the acid.
    this unit uses 404A. and the condenser is 3 months old!! but the one adjacent to it is 10-15 years old and no doubt "encrusted". But they both are having the same problem within a week of each other. However it is possible for different reasons. The old one because of fouled condenser tubes and possibly the new one is overcharged. I will take more measurements tommorow.... subcooling and your suggested approach temp will be very informative. much thanks

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