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  1. #1

    Rack Heat Reclaim for 100% comfort heat.

    How is the best way to control the Heat Reclaim from a Multiplex Rack, when it's used as 100% comfort heating to an AHU?

  2. #2
    Join Date
    Feb 2008
    Location
    California
    Posts
    2,066
    with a space temperature sensor that controls a heating relay.

  3. #3
    Join Date
    Sep 2008
    Location
    Western PA
    Posts
    25,690
    Funny about heat reclaim.

    My major customer is now pushing an initiative to shut down their heat reclaim.

    Somebody, somehow proved to them that using heat reclaim was more expensive than shutting it off and using gas.




  4. #4
    Join Date
    Sep 2007
    Location
    NH
    Posts
    1,155
    Quote Originally Posted by jpsmith1cm View Post
    Funny about heat reclaim.

    My major customer is now pushing an initiative to shut down their heat reclaim.

    Somebody, somehow proved to them that using heat reclaim was more expensive than shutting it off and using gas.



    It was probably the gas company.. Hahahaha

  5. #5
    Join Date
    Sep 2008
    Location
    Western PA
    Posts
    25,690
    I know who did it and how they did it.

    It was a bit of sleight of hand, IMO, and it'll come full circle in a few years.

  6. #6
    Join Date
    Oct 2011
    Location
    East Charlotte Area of NC
    Posts
    426
    Had a similar thing happen to a smaller chain here years ago. Someone came in and had this big spreadsheet of how much the heat was costing them off the rack due to the energy the compressors used to provide that heat. Then they showed "how much more cost effective" it was to run gas than "running all those compressors". Numbers looked astounding, except for the fact the compressors are still running, which they ever so quietly left out of the final numbers, regardless if you are using heat reclaim or not.

    And JP, I doubt it will take more than 6 months to come full circle when they see nothing really changed except the additional cost of heating without reclaim.

    I can't fix it if it won't stay broke..

  7. #7
    There's an older microelectronic Honeywell controller where the dry contacts are some how energizing the smaller rack's heat reclaim. Both rack's heat reclaims are rigged together now.
    It does seem like a waste in efficiency since the motor room and AHU are on different sides of the store. So now I'm thinking of putting in a new 230 VAC control circuit for the heat reclaim valve solenoids. Of course, it would come from the space controller and be interrupted by a air pressure switch at the AHU and a outdoor ambient lockout switch. What do you think?

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