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Water cooled DX coil with water-side economizer

I have a design using water-cooled CRAC unit in service room with water-side economizer. I simulate the DX cooling using this method, But it gives me following error:

Severe * FindRootSimpleController: Controller error for controller = "CONTROLLER WATER COIL 1" * ~~~ * Environment=NEW YORK LAGUARDIA ARPT ANN CLG .4% CONDNS DB=>MWB, at Simulation time=07/21 00:00 - 00:15
*
~~~ * 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 = 13.56 [C] * ~~~ * Controller sensed temperature = 22.33 [C] * ~~~ * Controller actuator mass flow rate set to 1.00 [kg/s] * ~~~ ** Controller actuator temperature = 22.35 [C]

Any one has idea what happens?

Thanks in advance!

Yuki's avatar
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Yuki
asked 2016-11-16 15:43:42 -0500
MatthewSteen's avatar
10.1k
MatthewSteen
updated 2016-11-16 15:57:38 -0500
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1 Answer

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This error is saying that the temperature of the water coming into the cooling coil is too hot to provide cooling to the air. So when EnergyPlus opens the valve to increase the flow rate it doesn't provide more heating and the numerical solver fails.

My guess is that the controls for the water-side economizer aren't working correctly. Double-check the control type for the HX and all the setpoints and sizing variables for the water loops. Plot the supply outlet temperatures for both loops to see if/when they aren't providing cold enough water.

aparker's avatar
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aparker
answered 2016-11-16 18:06:14 -0500
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