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Commercial WS Heat Pump Control

A water source heat pump used for a small server room. The load is pretty low but the room is small so it heats up fast and cools off fast. The diffferential on the heat pump thermostat is about 1 degree. The heat pump is cycling every five minutes (5 mins. to heat up, 5 mins. to cool down). The concern is how long will the heat pump last. If the thermostat differencial were higher the cycle would be longer. I think that the simple data switches, etc. would not have a problem with a few degrees swing, but am not sure. I would think the heat pump would be better off.


  • Empire_2
    Empire_2 Member Posts: 2,343
    Ah.Server rooms and the like....

    My friend, it is a vicious cycle due to the fact that you are controlling the space temp in a room that has anywhere from 10K to 50 million dollars worth of equipment.  In this situation, do not concern yourself with energy savings.  These rooms are never to fail and if I had any thing to say about it, A redundant piece of equipment would be installed to back up the original one.

         Liebert equipment has a good reputation for these rooms and generally this is what we use.

    Mike T.
  • eluv8
    eluv8 Member Posts: 174
    edited January 2010
    Cycling Problems

    If this has a hydronic fan coil to reduce the cycling simply increase or (add) a buffer storage tank between the fan coil and the heat pump.  If the heat pump has its own fan coil, there is not a whole lot you can do unfortunately it sounds like it was grossly oversized for the server room and youll have to find a thermostat that will allow as big of an adjustment as possible between on and off.
  • Wayne_16
    Wayne_16 Member Posts: 130
    Braeburn thermostats have an adjustable differential

    Check the braeburn catalog.  They have thermostats available with a adjustable differential.  I run across one last fall on a gshp using this thermostat exactly for that reason.


    Minnesota Wayne
  • Empire_2
    Empire_2 Member Posts: 2,343

    I'm not sure if you were able to come to a conclusion, but I have a few Q:?...  DO they plan on ading more equipment in the future?  Like stated before the unit may be oversized, but remember these rooms should be able to cool, de-humidify, and also reheat at the same time.  Bottom line, If this equipment in this room is critical, it's time to update the HVAC.

         Let us know what the final outcome is for this project.

    Mike T.
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