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  1. #1
    Join Date
    May 2008
    Location
    nashville,tn
    Posts
    8

    Confused non-spring return control valves - need help w/ question

    Are there any applications in which non-spring return control valves would be preffered over the fail-safe control valves. In a hot water system w/ 3 & 2 way control valves serving fan coil units, are spring return control valves necessary and in which position should the default position be?
    Last edited by ALee13; 05-10-2008 at 06:27 PM.

  2. #2
    Join Date
    Jan 2005
    Posts
    605
    From what you're askin', the default position woud be, where ever they were when power was interupted (for what ever reason).

  3. #3
    Join Date
    Jan 2008
    Location
    windy city
    Posts
    4,441
    yes there are default (failsafe). you should fill out your profile so we know who you are so your inquiries can be properly processed.

  4. #4
    Join Date
    May 2008
    Location
    nashville,tn
    Posts
    8
    For hot/chilled water valves, when power is lost, I would think that you would want all of the three-way valves to remain in the position that they were currently in, and have all of the two way valves have open has there default position, but I don't know.

    When are spring return control valves needed and what should the default position be for those control valves serving fan coil units?

  5. #5
    Join Date
    Aug 2000
    Location
    USA
    Posts
    4,995
    Are you sueing someone over a design issue or asking a theoretical question?
    Quote Originally Posted by ALee13 View Post
    For hot/chilled water valves, when power is lost, I would think that you would want all of the three-way valves to remain in the position that they were currently in, and have all of the two way valves have open has there default position, but I don't know.

    When are spring return control valves needed and what should the default position be for those control valves serving fan coil units?
    Your poor planning does not constitute an emergency on my part!!!!

  6. #6
    Join Date
    May 2008
    Location
    nashville,tn
    Posts
    8
    I'm just asking a general question.

  7. #7
    Join Date
    Sep 2006
    Location
    Rhode Island
    Posts
    244
    Usually a fail safe control valve cost more than a valve that stays in the same position during a power failure to the valve. A design engineer might specify non-failsafe valves to save a few bucks on a construction project and only use failsafe valves in critical areas. For instance if you had a fan that was providing heating and cooling for a computer room and you lost power to your controls and valves but the fan continued to run you wouldn’t want to take a chance that the heating valve failed open on that rare occasion that the room was calling for heat. So that would be an application where you might want to have a failsafe to closed valve. On the other hand you might want your cooling valve to failsafe to open.

    To answer your question... It all depends on the application

  8. #8
    Join Date
    Feb 2008
    Location
    Toronto, Ontario, Canada
    Posts
    19
    for zone/room heating and cooling, it's better to have fail in place. The load in the zone isn't likely to change drastically so whatever position the valve is in already is close to where it should be.

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