Results 1 to 9 of 9
  1. #1
    Join Date
    Aug 2009
    Location
    india
    Posts
    9
    Rep Power
    0

    why is motorized valve located in the outlet line of fan coil unit



    i want to know ,why not in the supply line,is this so that line will not become empty of chilled water.



  2. #2
    Join Date
    Jul 2009
    Location
    Berkshire
    Age
    50
    Posts
    175
    Rep Power
    15

    Re: why is motorized valve located in the outlet line of fan coil unit

    I am assuming this is a 2-port valve which just opens and closes the water flow? Generally the supply to a chilled water fan coil is at the bottom of the coil and exits at the top of the coil. This is to drive any air out of the system. With your pumps circulating water around the system, when the valve is closed, water won't circulate through the fan coil unit. It is a basic system. If all your fan coil units only have 2-port valves, you must have a pump by-pass circuit somewhere, otherwise there may be occasions when all the valves are closed and the pump pushes against a blockage! Hope this helps.

  3. #3
    Brian_UK's Avatar
    Brian_UK is offline Moderator I am starting to push the Mods: of RE Site Moderator : and general nice guy
    Join Date
    Mar 2001
    Location
    Dorset
    Age
    76
    Posts
    11,192
    Rep Power
    60

    Re: why is motorized valve located in the outlet line of fan coil unit

    It doesn't really make any difference where the valve is situated, the effect is the same.
    Brian - Newton Abbot, Devon, UK
    Retired March 2015

  4. #4
    Join Date
    Dec 2008
    Location
    Portugal
    Age
    48
    Posts
    1,044
    Rep Power
    19

    Re: why is motorized valve located in the outlet line of fan coil unit

    Maybe in that way you have more certain that the air trapped can be expel from the coil, even when the fan coil is stopped. Also when the fan coil is working due to the pressure drop in the valve the coil will be "more filled" with brine (with less air) which could increase a little the heat convective coefficient on the brine side.

    Of course I believe there are many situation which the effect can be no noteciable.
    To make progress is never good enough, I want to do better and better and better

  5. #5
    Join Date
    Aug 2007
    Location
    Sydney
    Age
    51
    Posts
    1,094
    Rep Power
    23

    Re: why is motorized valve located in the outlet line of fan coil unit

    Another reason for control valves to be placed on outlet is some older coils have air purgers which work beter under more pressure. As for heating and cond water valves it reduces any air buble sizes and increases heat tranfer. The old pressure/temperature/volume relationship.

  6. #6
    Join Date
    Mar 2009
    Location
    KZN, South Africa
    Age
    63
    Posts
    2,212
    Rep Power
    20

    Re: why is motorized valve located in the outlet line of fan coil unit

    Where would a water flow control valve be best positioned?

    Exit of HE, or inlet & why?
    Engineering Specialist - Cuprobraze, Nocolok, CD Technology
    Rarefied Technologies ( SE Asia )

  7. #7
    Join Date
    Aug 2005
    Location
    USA
    Posts
    5,326
    Rep Power
    25

    Re: why is motorized valve located in the outlet line of fan coil unit

    I was always told the control valves on water coils go on the exit to prevent from air binding the coil.
    If all else fails, ask for help.


  8. #8
    Join Date
    May 2009
    Location
    Australia
    Posts
    16
    Rep Power
    0

    Re: why is motorized valve located in the outlet line of fan coil unit

    There is no difference in placing the control valve at inlet or out let of FCU.If you place at outlet side the coil is filled with water always and it can give some heat transfer even when the valve is closed.Also airvent is located on top outlet of FCU which interm assist in purging.

  9. #9
    Join Date
    Jan 2009
    Location
    Jakarta
    Posts
    7
    Rep Power
    0

    Re: why is motorized valve located in the outlet line of fan coil unit

    because of the arrangement flow that needed by the fcu, when motorized valve located in the outlet fcu, any movement of mv (like open or close) will cause influence flow of water (gpm). for example if mv has signal from thermostat or room temp sensor that order it to open only 25%, the speed of water flow in coil fcu will decrease because the mv that located in outlet fcu only open in 25 % and then cause of the heat transfer process because the reduce water flow that contact by air. it will different if mv located in inlet fcu

Similar Threads

  1. Dont be shy, advice needed.
    By Sledge in forum Air Conditioning
    Replies: 9
    Last Post: 27-06-2007, 03:09 PM
  2. Off-line Mitsi VRF leaks!
    By sinewave in forum Air Conditioning
    Replies: 8
    Last Post: 05-06-2007, 11:18 PM
  3. Siemens Motorized Valve
    By nh3wizard in forum NH3
    Replies: 2
    Last Post: 08-05-2006, 09:48 PM
  4. Parker levels in ammonia systems
    By Friobernal in forum Industrial
    Replies: 3
    Last Post: 04-08-2005, 03:46 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •