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  1. 09-10-2012, 10:05 AM #1
    hobbit
    hobbit is offline Regular Guest
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    EXV forced closure?

    I recently noticed that my air handler / indoor coil has a pair
    of dry-contact input terminals to force its EXV to CLOSED during
    cooling mode.

    When/why would you want to do this, and/or why would such a
    function want to be able to be externally automated? I can't
    imagine how it could be good for the rest of the system.

    tnx

    _H*
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  2. 09-10-2012, 12:30 PM #2
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    Shophound
    Shophound is offline Professional Member*
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    What indicates that this is what the set of dry contacts are for? Dry contacts are often for alarm triggering purposes.
    Building Physics Rule #1: Hot flows to cold.


    Building Physics Rule #2:     Higher air pressure moves toward lower air pressure


    Building Physics Rule #3:     Higher moisture concentration moves toward lower moisture concentration.
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  3. 09-10-2012, 12:40 PM #3
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    ryan1088
    ryan1088 is offline Professional Member*
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    Hobbit it this on your Daikin system we have talked about before?
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  4. 09-10-2012, 02:03 PM #4
    hobbit
    hobbit is offline Regular Guest
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    Thread Starter
    Yup, the Daikin FTQ type air handler. Quoting from the
    install manual description for option block terminals 9,10:
    "Receives input: Forced closure of indoor unit Electronic
    Expansion Valve during cooling operation. (dry contact)"

    Seems like a strange thing to want an input for. Note: this
    isn't the same as "forced off" that you'd use for safety
    switches, condensate-pump overflows, etc.

    _H*
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  5. 09-10-2012, 02:20 PM #5
    Elfshadow
    Elfshadow is offline Professional Member
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    Sorries did not notice this was in the ask a pro section.
    Last edited by Elfshadow; 09-10-2012 at 02:42 PM. Reason: was in wrong section.
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