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  1. #1
    Join Date
    Mar 2010
    Posts
    19

    cooling tower bypass valve

    how to verified if cooling tower bypass valve is good ?
    just for testing purpose in hot weather.

  2. #2
    Join Date
    Dec 2009
    Location
    Fort Worth, Texas
    Posts
    152
    check the signal and power voltage to actuator if pneumatic then check air pessure.
    raise the signal voltage or pressure to 100% and see if valve fully opens or closes, then take signal or pressure to 0% and see if valve fully closes or opens. depends on the action.
    also check to see if condenser water temperture mantains close to setpoint ( somewhere around 80 degrees) if not then check tower, water ports,nozzles and orfices.
    clean if needed.
    good luck

  3. #3
    Join Date
    Jan 2005
    Location
    Houston TX
    Posts
    880

    Cooling tower by-pass

    Well that will varify if the actuator is working, but you also want to check and make sure the valve itself is working. If it blocks flow from going over the top of tower hot deck and directly back to the condenser water supply or does it interconnect in the condenser water piping below the tower in a central plant. The valve could be jammed and not actuating. -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

  4. #4
    Join Date
    Dec 2009
    Location
    Fort Worth, Texas
    Posts
    152
    my bad, better make sure valve moves with actuator.

  5. #5
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
    Posts
    11,376
    Quote Originally Posted by HJ Controls View Post
    check the signal and power voltage to actuator if pneumatic then check air pessure.
    raise the signal voltage or pressure to 100% and see if valve fully opens or closes, then take signal or pressure to 0% and see if valve fully closes or opens. depends on the action.
    If it's a hot day, playing with the tower bypass could cause the chillers to surge if they're centrifugal chillers.

    also check to see if condenser water temperture mantains close to setpoint ( somewhere around 80 degrees) if not then check tower, water ports,nozzles and orfices.
    clean if needed.
    good luck
    That depends on how the towers are set up to maintain condenser water supply temp. Some do it by banging the fan on and off. Others have VFDs on the tower fans. Tower bypass strategies typically kick in during cold weather.
    • Electricity makes refrigeration happen.
    • Refrigeration makes the HVAC psychrometric process happen.
    • HVAC pyschrometrics is what makes indoor human comfort happen...IF the ducts AND the building envelope cooperate.


    A building is NOT beautiful unless it is also comfortable.

  6. #6
    Join Date
    Jul 2004
    Location
    Maryland
    Posts
    333

    figuring valve Port opening %

    You could use Temperature readings

    place a accurate temperature sensor near each port ( I try and keep them 24 inches or so away for better accuracy readings). Stroke the valve to 0% wait x amount of minutes for readings to stabilize. The stroke valve to 100% wait x amount and Document readings. This should tell you if your valve is fully open to the tower or fully bypassed.
    Should work for mixing or diverting valve set ups.
    IF mixing you should be able to document the actual percentage % by using this formula ( same one you use for setting min OA damper position by temperature.
    % OAT = MAT - RAT / OAT - RAT



    % AT= CT - BT / AT - BT



    AT= N.C port temp BT= N.0 Temp and CT= Common Temp.

  7. #7
    Join Date
    Jul 2004
    Location
    Maryland
    Posts
    333

    figuring valve Port opening %

    Double post sorry
    Last edited by pringlel; 06-19-2011 at 11:04 AM. Reason: Double post

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