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  1. #1
    Join Date
    May 2009
    Posts
    64

    Anybody with experience with a VSD on a pump motor with a mixing valve??

    have a heating pump motor thats on 24/7 - cant be turned off but on warmer days it makes sense to reduce rpm on pump motor. system has a mixing valve so water flow is necessary all the time.

    considering installing a programmable VSD to reduce power use of motor. VSD would be set to reduce rpm over night and also manually reduce it when there is minimal heat demand.

    thanks

  2. #2
    Join Date
    Feb 2006
    Location
    SouthEastern Virginia
    Posts
    1,077
    Can you attach a drawing of the piping arrangement?
    It might get loud!

  3. #3
    Join Date
    Mar 2011
    Location
    East Coast FL
    Posts
    1,065
    True you really have to look at how its piped.

    Is it a manual or automated mixing valve?

    Good idea , I think , VFD on pumps , great.

  4. #4
    Join Date
    Apr 2010
    Location
    southern california
    Posts
    535
    Need piping diagram or some pictures, how large of a pump are we talking about and what is the minimum flow rate needed.

  5. #5
    Join Date
    Dec 2005
    Posts
    1,923
    If the sytem has ONLY 3-way mixhing valves, then you cannot reduce the pump's rpm. Because, the further valve will not have enough water.

    You may wanna hire a knowledgeable contractor to survey your system and to recommend another way of operation to reduce your power consumption.

    Good luck

  6. #6
    Join Date
    Jun 2010
    Location
    U.A. (upper Alabama)
    Posts
    873
    Quote Originally Posted by zeppy View Post
    have a heating pump motor thats on 24/7 - cant be turned off but on warmer days it makes sense to reduce rpm on pump motor. system has a mixing valve so water flow is necessary all the time.

    considering installing a programmable VSD to reduce power use of motor. VSD would be set to reduce rpm over night and also manually reduce it when there is minimal heat demand.

    thanks
    We had one building that had three way valves all throughout, with a VSD. We went in and made blankoffs for the bypasses on all but the end of the piping air handler. We done this to keep hot or chilled water in the system so if an air handler called for chilled or hot water it would have it there already. We are saving alot of tax dollars in electricity to.

  7. #7
    Join Date
    May 2009
    Posts
    64
    the system has only one mixing valve which is right by the the boiler. the mixing valve is automatically controlled. need to keep water flow to keep a balance between boiler water and water flow to rest of facility

    the heating pump motor is 15 HP with 1700 rpm

    the goal is to reduce the rpm with a variable drive (or at least allow flexibility) during periods with lower heat demand

    has anyone done this?

    thanks

  8. #8
    Join Date
    Feb 2006
    Location
    SouthEastern Virginia
    Posts
    1,077
    Still not enough information. Please draw a layout of the system so we can see into the crystal ball. The mixing valve does not tell us enough about the big picture.
    It might get loud!

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