.Buildings.Templates.Plants.Controls.HeatRecoveryChillers.Enable

Information

The available CHW load QChiWatReq_flow is calculated based on secondary CHW temperature immediately upstream of the heat recovery chiller, active CHW supply temperature setpoint and secondary CHW loop flow.

The available HW load QHeaWatReq_flow is calculated based on secondary HW temperature immediately upstream of the heat recovery chiller, active HW supply temperature setpoint and secondary HW loop flow.

The available CHW and HW loads used in logic are rolling averages over a period of dtMea of instantaneous values sampled at minimum once every 30 s.

The heat recovery chiller is enabled when all of the following are true:

• CHW plant has been enabled for dtRun.
• QChiWatReq_flow > capCooHrc_min for dtLoa.
• HW plant has been enabled for dtRun.
• QHeaWatReq_flow > capHeaHrc_min for dtLoa.
• HRC has been disabled for at least dtRun.

The heat recovery chiller is disabled when any of the following are true:

• CHW plant is disabled.
• HW plant is disabled.
• The heat recovery chiller cycles off (chiller is enabled but status changes from Run to Off) under low load conditions and either QChiWatReq_flow < capCooHrc_min or QHeaWatReq_flow < capHeaHrc_min.
• If the HRC is in heating mode and CHW supply temperature leaving the heat recovery chiller as measured either through the chiller’s network interface or immediately downstream of the chiller is < TChiWatSupSet_min + 1 for dtTem1 or < TChiWatSupSet_min for dtTem2.
• If the HRC is in cooling mode and HW supply temperature leaving the heat recovery chiller as measured either through the chiller’s network interface or immediately downstream of the chiller is > THeaWatSupSet_max - 1.5 for dtTem1 or > THeaWatSupSet_max for dtTem2.

Pump control

Sidestream HRC HW and CHW pumps are enabled when the heat recovery chiller is enabled.

Revisions

• May 31, 2024, by Antoine Gautier:
  First implementation.