.Buildings.Templates.Plants.Controls.Setpoints.PlantReset .Buildings.Templates.Plants.Controls.Setpoints.PlantResetThis logic is used in primary-only and primary-secondary systems serving differential pressure controlled pumps.
The CHW supply temperature setpoint and pump differential pressure setpoint are reset based on the current value of the logic variable called "CHW Plant Reset" as shown below and described subsequently.
The HW supply temperature setpoint and pump differential pressure setpoint are reset based on the current value of the logic variable called "HW Plant Reset" as shown below and described subsequently.
From 0 % loop output to resDp_max loop output, reset
differential pressure setpoint from dpSet_min to dpSet_max.
From resTSup_min loop output to 100 % loop output, reset supply
temperature setpoint from TSupSetLim to TSup_nominal.
CHW/HW Plant Reset variable is reset using trim and respond logic with the following parameters:
| Variable | Value | Definition |
|---|---|---|
| Device | Any pump distribution loop | Associated device |
| SP0 | res_init | Initial reset value |
| SPmin | res_min | Minimum reset value |
| SPmax | res_max | Maximum reset value |
| Td | dtDel | Delay time before the reset begins |
| T | dtRes | Time step |
| I | nReqResIgn | Number of ignored requests |
| R | nReqRes | Number of requests |
| SPtrim | tri | Trim amount |
| SPres | rsp | Respond amount |
| SPres_max | rsp_max | Maximum response per time interval |
The plant reset loop is enabled when the plant is enabled and disabled when the plant is disabled.
When a plant stage change is initiated, the plant reset logic is disabled and
value fixed at its last value for the longer of dtHol and the time it
takes for the plant to successfully stage.
A unique instance of the above reset is used for each set of differential pressure controlled pumps.
Where more than one remote ∆p sensor serves a given set of primary or secondary pumps,
remote ∆p setpoints for all remote sensors serving those pumps shall increase in unison.
Note: if remote sensors have different dpSet_max values, then the amount
each ∆p setpoint changes per percent loop output will differ.