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CHW cooling coil Error

asked 2015-06-21 09:51:28 -0500

Kastro1501's avatar

updated 2015-07-11 17:25:49 -0500


I'm trying to setup an AirLoopHVAC according to figure image description

Heating coil is connected to Boiler loop, and Cooling coil (CHW) is connected to Chiller loop. The air loop has setpoint manager single loop with referenced thermal zone for control. Zone is to be kept at 25ºC maximum, for occupied periods.

When running sim on OS, I keep getting the same warning:

Warning * SizeWaterCoil: Coil="CHWCLGCOIL", Cooling Coil has leaving air temperature > entering water temperature. * ~~~ * Tair,out = 12.800 * ~~~ * Twater,in = 82.000 * ~~~ * ....coil leaving air temperature will be reset to: * ~~~ * Tair,out = 82.500*"

The schedule for cooling coil loop (chiller loop) is defined with water leaving chiller at 7ºC, so i find this a bit surreal. I've checked the coils connection nodes and they are differently numbered so a think this is not the problem.

Why do I keep getting the error/warnig above?


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@Kastro, question tags are used to route questions to other users who are interested or experienced in certain topics. Users subscribe to tags by marking them interesting in the box on the right had ribbon. They can then set their personal settings to receive email when questions with these tags are asked. To make email routing work, you have to tag questions with tags that people are likely to subscribe to, and a good guide to these is the stream of tags on the right, e.g., 'openstudio', 'energyplus', 'hvac', 'vrf', etc. Happy tagging. Hope you are finding the site useful!

__AmirRoth__'s avatar __AmirRoth__  ( 2015-06-21 15:27:56 -0500 )edit

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answered 2015-06-22 08:26:28 -0500

Click on the center of the chilled water plant and inspect the sizing properties. I believe you have sizing inputs that reflect a hot water plant instead of chilled water. It may not be intuitive, but the sizing inputs in EnergyPlus are decoupled from the setpoint based operation of the annual simulation.

If you build a system from one of the templates these settings will be setup for you, but if you build a plant up from scratch you will have to adjust these settings manually.

image description

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Kyle, I have clicked almost everywhere on that template, and I never thought of clicking there.

Simple things solce great problems.


Kastro1501's avatar Kastro1501  ( 2015-06-22 09:35:02 -0500 )edit

Just had the same issue with a built-from-scratch CW loop; default setting was "heating", which I sheepishly changed to "condenser" after reading this Q&A. Problem solved; UnmetHours comes through again!

NickC's avatar NickC  ( 2015-11-10 15:55:07 -0500 )edit

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Asked: 2015-06-21 09:51:28 -0500

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Last updated: Jun 22 '15