Setpoints and related data
The setpoints and related data include the following items:
- Power exhaust fan type (ExFType) variable frequency fan
- Building pressure setpoint (Bldg-Sp)
- Building pressure reading (Bldg-Pres)
Inputs
The input for modulating power exhaust with VFD is 0 to 5 VDC from building pressure sensor to terminal BLDG PRES.
Outputs
The outputs include the following items:
- 2 to 10 VDC from EX VFD
- 24 VAC from EX-FAN
Operation
If the building pressure is above the building pressure setpoint, the exhaust output (EX VFD) increases. If the building pressure is below the building pressure setpoint, the exhaust output (EX VFD) decreases.
The EX-FAN binary output is energized any time the EX VFD analog output is greater than 2.16 VDC.
The EX-FAN binary output is de-energized any time the EX VFD analog output is less than or equal to 2.16 VDC.
The rate of change of the analog output is determined by the deviation form setpoint and length of time away from setpoint.