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GSHP with DualSetpoint control

asked 2016-10-11 16:45:15 -0500

mleach gravatar image

updated 2017-05-06 08:23:53 -0500

I'm trying to control a GroundHeatExchanger:Vertical object using SetpointManager:Scheduled:DualSetpoint so that it runs when the condenser loop drops below 50 F and when the condenser loop rises above 75 F. In between 50 F and 75 F, the condenser loop should float and the GroundHeatExchanger:Vertical should be off (no flow, no heat transfer). To do this, I took the following steps:

  1. Created a SetpointManager:Scheduled:DualSetpoint object and applied it to the plant side outlet node of the condenser loop. The low temperature schedule is always 50 F and the high temperature schedule is always 75 F. Note that I tried an alternate version where I applied an identical version of the same setpoint manager to the outlet node of the GroundHeatExchanger:Vertical, but it didn't seem to make any difference.
  2. Set the Plant Loop Demand Calculation Scheme in the condenser loop PlantLoop object to DualSetPointDeadband
  3. Created a PlantEquipmentOperationSchemes object with PlantEquipmentOperation:HeatingLoad and PlantEquipmentOperation:CoolingLoad objects and assigned the PlantEquipmentOperationSchemes object to the Plant Equipment Operation Scheme Name field in the condenser loop PlantLoop object. The GroundHeatExchanger:Vertical is assigned as the equipment for both the HeatingLoad and CoolingLoad control schemes and both control schemes are set to Always On.

When I run the model, it works fine on the cooling side but the GroundHeatExchanger:Vertical never comes on for heating. The condenser loop cooling and heating demand output variables look correct based on the temperature schedules assigned to the DualSetpoint manager, and GroundHeatExchanger:Vertical operation in cooling seems to sync perfectly with condenser loop cooling demand. I just can't figure out why it doesn't work in heating.

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answered 2016-10-17 10:10:17 -0500

updated 2016-10-17 16:25:32 -0500

Take a look at this tutorial on how to setup setpoint managers on condenser loops.

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Are you sure of that? The 5ZoneWLHPPlantLoopTower.idf example file uses a SetpointManager:Scheduled:DualSetpoint set point manager.

Jeremy gravatar image Jeremy  ( 2016-10-17 14:22:37 -0500 )edit
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Sorry, I had it backwards. SetpointManager:Scheduled:DualSetpoint is applicable is for a plant loop that has both heating and cooling equipment on it. The "high" setpoint is a cooling setpoint, and the low setpoint is used as a heating setpoint. So it should work if the Plant Loop Demand Calculation Scheme is set to DualSetpointDeadband. I've corrected my response above

Lincoln gravatar image Lincoln  ( 2016-10-17 16:25:17 -0500 )edit

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Asked: 2016-10-11 16:45:15 -0500

Seen: 375 times

Last updated: Oct 17 '16