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Fluid Cooler and Chiller staging

asked 2020-04-18 12:47:21 -0500

Jim Dirkes's avatar

updated 2020-04-20 12:33:03 -0500

It seems that this should be simpler.... I would like to model a chilled water cooling loop with a fluid cooler and chiller. The fluid cooler should operate at cold outdoor temps (eg, 3C and below). The air-cooled chiller should operate at higher outdoor temps (eg, > 3C)

Implementing that idea is eluding me after trying many options. It would be handy, for example, to use PlantEquipmentoperation:OutdoorDryBulb, but that is applicable only for condenser loops.

Can someone give a little guidance regarding a workable approach? Thanks very much.

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I've made some progress using EMS. There are now two EMS:Programs, both of them change a schedule:compact value from 1 to 0 depending on the outdoor temperature. One changes schedule #1's value to zero when outdoor temp is BELOW 5C. the other changes schedule #2's value to zero when outdoor temp is ABOVE 5C.

For some reason, all works well when the outdoor temp >5C - only the chiller operates. Below 5C, however, BOTH the chiller and fluid cooler operate. The EMS:Programs report the correct schedule value, so something is allowing the fluid cooler to run >5C

Still hoping for help!

Jim Dirkes's avatar Jim Dirkes  ( 2020-04-20 12:39:49 -0500 )edit

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answered 2020-04-20 13:44:57 -0500

Jim Dirkes's avatar

Figured it out! Only took about 20 tries :(

PlantEquipmentOperationSchemes, as is clearly stated in the documentation, applies each scheme in a priority. My priority was OK, but definitions for the default EMS:Program values were off.

Happy to share more details if anyone is interested.

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Asked: 2020-04-18 12:47:21 -0500

Seen: 218 times

Last updated: Apr 20 '20