9-4
P22 - Accessory Function
Terminals Ac1 and Ac2 on the Fan Coil Thermostat provide output to an accessory such as a Humidifier,
Dehumidifier, Heat Recovery Ventilator (HRV) or Energy Recovery Ventilator (ERV) .The built-in humidity
monitor continually samples humidity at the thermostat and will operate a humidifier or dehumidifier to
maintain the specified value . The Table 9 .3 shows the function of the accessory output depending on which
accessory is selected under parameter 22 (See Appendix A) .
Table 9.3: Parameter 22 - Accessory Function
Parameter P22 Setting
Operation of Ac1/Ac2 dry contacts
0 (No Function)
Open
1 (Humidifier)
Closed when humidity is at
or below the set point
Open when the humidity
exceeds the set point
2 (Dehumidifier)
Closed when humidity is at
or above the set point
Open when the humidity is
less than the set point
3 (ERV/HRV)
Closed when fan relay is on
Open when fan relay is off
The icon is displayed when the Ac1/Ac2 dry contacts are closed .
Section 9
SC102ZB/ST103ZB Installation and Operation Manual
Operation
