How to get water source cooling coils to work in air loops

asked 2017-03-20 17:11:18 -0500

wes gravatar image

First off I want to say that this is my first post here so I apologize if it isn't in the right format. I am having problems with the cooling coils in my simulation. I am trying to get a geothermal heat pump condenser loop to create water at ground temperature using district heating and cooling objects as one of the tutorials on here suggest doing. Then I have a hot water loop and cold water loop that use water to water heat pumps to create the hot or cold water. These loops then have coils for each of the air loops in the building (one air loop for each floor, and a separate one for a lab space with high ventilation requirements). When I run I get these errors for each of the cooling coils:

* Warning * SizeWaterCoil: Coil="CHW CLG COIL", Cooling Coil has leaving humidity ratio > entering humidity ratio.

* ~~~ * Wair,in = 7.635708E-003

* ~~~ * Wair,out = 9.569175E-003

* ~~~ * ....coil leaving humidity ratio will be reset to:

* ~~~ * Wair,out = 7.635708E-003

* Severe * Calculation of cooling coil design UA failed for coil CHW CLG COIL

* ~~~ * Bad starting values for UA

* ~~~ * Coil design UA set to 9920.778579 [W/C]

I have tried playing with the setpoint values that I can access in Openstudio and still get these errors, and I have no idea how to fix them. I have looked at some other people's questions similar to this and have not been able to get those to work or understood how to implement their solutions.

I also have another error for the air loop serving the labs with the high flow rate:

* Severe * FindRootSimpleController: Controller error for controller = "CONTROLLER WATER COIL 11"

* ~~~ * Environment=RUN PERIOD 1, at Simulation time=08/03 16:50 - 17:00

* ~~~ * Controller function is inconsistent with user specified controller action = Reverse action

* ~~~ * Actuator will be set to maximum action

* ~~~ * Controller control type=Temperature

* ~~~ * Controller temperature setpoint = 18.63 [C]

* ~~~ * Controller sensed temperature = 21.10 [C]

* ~~~ * Controller actuator mass flow rate set to 0.65 [kg/s]

* ~~~ * Controller actuator temperature = 21.10 [C]

* ~~~ * Note: Chilled water coils should be reverse action and the entering chilled

* ~~~ * water temperature (controller actuator temperature) should be below the setpoint temperature

* ~~~ * Note: Hot water coils should be normal action and the entering hot

* ~~~ * water temperature (controller actuator temperature) should be above the setpoint temperature

* Warning * Plant Loop: DHW Demand Side is storing excess heat the majority of the time.

* Warning * Plant Loop: DHW Supply Side is storing excess heat the majority of the time.

Again I have no idea how to fix this error, and I have tried doing what the notes suggest. So any help I can get with this would be great.

Cheers, Wes

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