.Buildings.Obsolete.Controls.OBC.ASHRAE.G36_PR1.TerminalUnits.Reheat.DamperValves .Buildings.Obsolete.Controls.OBC.ASHRAE.G36_PR1.TerminalUnits.Reheat.DamperValvesThis sequence sets the damper and valve position for VAV reheat terminal unit. The implementation is according to ASHRAE Guideline 36 (G36), PART 5.E.6. The calculation is done following the steps below.
When the zone state is cooling (uCoo>0), then the cooling loop output
uCoo shall be mapped to the airflow
setpoint from the cooling minimum VActCooMin_flow to the cooling maximum
VActCooMax_flow airflow setpoints. The hot water valve is closed (yHeaVal=0)
unless the discharge air temperature TDis is below the minimum
setpoint (10 °C).
If supply air temperature TSup from the AHU is greater than
room temperature TZon, cooling supply airflow setpoint shall be
no higher than the minimum.
When the zone state is Deadband (uCoo=0 and uHea=0), then
the active airflow setpoint shall be the minimum airflow setpoint VActMin_flow.
Hot water valve is closed unless the discharge air temperature is below the minimum
setpoint (10 °C).
When the zone state is Heating (uHea>0), then
the heating loop shall maintain space temperature at the heating setpoint
as follows:
uHea shall reset the
discharge temperature setpoint from current AHU SAT setpoint TSup
to a maximum of dTDisZonSetMax above space temperature setpoint. The airflow
setpoint shall be the heating minimum VActHeaMin_flow.TDis is
greater than room temperature plus 2.8 Kelvin, the heating loop output uHea
shall reset the airflow setpoint from the heating minimum airflow setpoint
VActHeaMin_flow to the heating maximum airflow setpoint
VActHeaMax_flow.The hot water valve (or modulating electric heating coil) shall be modulated to maintain the discharge temperature at setpoint.
The VAV damper shall be modulated by a control loop to maintain the measured airflow at the active setpoint.
The sequences of controlling damper and valve position for VAV reheat terminal unit are described in the following figure below.
