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  1. #1
    Join Date
    Sep 2010
    Location
    Livingston, Montana
    Posts
    16

    General guidelines for water-cooled A/C and heat pumps

    Can someone give me some general tips for setting water reg valves on water cooled units? Specifically, what sort of delta T are we looking for? What sort of condensing temps/pressures? My incoming water temps to the condenser are very low, being fed from a building chiller. So, we're running around 48 degrees! The unit in question was originally on city water, which was around 55-60 degrees. I find my evap is freezing now, and I have to adjust the reg valve accordingly to bring up my leaving water temps and head pressure.
    Is there a general rule of thumb you can give me for setting reg valves?
    It's R-22 system, btw.

  2. #2
    Join Date
    Jan 2008
    Location
    Dallas ,Texas
    Posts
    3,718
    I would think you would want to set your valve for 200-225 discharge pressure. DeltaT is all going to depend on the valve opening up so it's irrelevant .
    Wow 48 degree condenser water is cold if you ask me , how's your airflow?

  3. #3
    Join Date
    Nov 2007
    Location
    Mississippi
    Posts
    1,347
    Would you expect an air cooled condenser to run properly on a 48* ambient day?

  4. #4
    Join Date
    Jul 2012
    Location
    Western KY
    Posts
    1,221
    What Dallas said.

  5. #5
    Join Date
    Sep 2010
    Location
    Livingston, Montana
    Posts
    16
    5 ton air handler on 5 ton semi hermetic compressor. Haven't checked airflow, but of course, all this was designed by the building engineer.
    I agree thoroughly...48 degrees is mighty cold incoming water. I think there has been a lot of undersight by engineering. Might be looking at corrective options, like hot gas bypass, etc... I don't see this working as it stands.

  6. #6
    Join Date
    Sep 2012
    Location
    Central Florida
    Posts
    885
    Quote Originally Posted by montanabama View Post
    5 ton air handler on 5 ton semi hermetic compressor. Haven't checked airflow, but of course, all this was designed by the building engineer.
    I agree thoroughly...48 degrees is mighty cold incoming water. I think there has been a lot of undersight by engineering. Might be looking at corrective options, like hot gas bypass, etc... I don't see this working as it stands.
    Is this unit a heat pump or straight cool? If its a heat pump I'm really hoping its outfitted with a freezestat. Also are the water coils and piping insulated? If they aren't you might have condensation issues with the colder water.

  7. #7
    Join Date
    Sep 2010
    Location
    Livingston, Montana
    Posts
    16
    Straight A/C, thank goodness. Adequate insulation. Reg valve is cranked down pretty hard...I guess we watch and see.

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