HVAC System Control - Setpoint Managers

The setpoint manager is the main mechanism through which the behaviour of HVAC system loops is controlled. All HVAC loops require at least one setpoint manager to specify the supply sub-loop outlet temperature and these are automatically included in all pre-defined HVAC loops. Setpoint managers will place a calculated or scheduled setpoint value at the point or connection in the loop at which the setpoint manager control line has been placed. No two setpoint managers should be located on the same connection for like control types otherwise an error message will be displayed and the simulation aborted.

There 15 different types of setpoint manager available. However only certain types of setpoint manager are available for different types of air loops and plant/condenser loops:

• 1-Scheduled (All loops).
• 2-Warmest (Generic and dual duct air loops only).
• 3-Coldest (Generic and dual duct air loops only).
• 4-Multi-zone minimum humidity average (Air loops only).
• 5-Multi-zone maximum humidity average (Air loops only).
• 6-Multi-zone humidity minimum (Air loops only).
• 7-Multi-zone humidity maximum (Air loops only).
• 8-Single zone humidity minimum (Air loops only).
• 9-Single zone humidity maximum (Air loops only).

• 10-Outdoor air reset (Generic and dual duct air loops, plant and condenser loops).

• 11-Single zone heating (Air loops only).
• 12-Single zone cooling (Air loops only).
• 13-Multi-zone cooling average (Air loops only).
• 14- Multi-zone heating average (Air loops only).
• 15-Follow ground temperature (Condenser loops only)

Refer to the Setpoint manager section for information regarding specific setpoint manager types.

Setpoint Manager used with Draw-Through Fans

Adjusting setpoints for fan pickup

When placing Setpoint managers on a node upstream of a draw-through fan you may need to manually adjust the setpoint to take into account the temperature rise that will take place as the air flows across the fan.

Mixed air Setpoint Managers

The Mixed Air Setpoint Manager is a special type of setpoint manager which is automatically added to air handling units that incorporate coils located before the supply fan and where no setpoint manager has been added explicitly before the fan. This type of setpoint manager works in conjunction with the AHU outdoor air controller (see Air Handling Unit Outdoor Air System). The Mixed Air Setpoint Manager is used to establish a temperature setpoint at the mixed air node. The AHU outdoor air controller then operates the outdoor air damper to attempt to meet this setpoint. The main function of the Mixed Air Setpoint Manager is to pick up a temperature setpoint provided by a setpoint manager located downstream of the supply fan and then set this value as the off-coil setpoint, having first subtracted the calculated temperature rise across the supply fan.

Note: A Mixed Air Setpoint manager is only included in systems that incorporate ‘draw-through’ coils. Also, if a setpoint manager is added in front of a draw-through fan, the Mixed Air Setpoint manager is omitted.