User Manual

Sequence of Operation

Auxiliary Sequences

Siemens Industry, Inc.

Application Note, App 14901

140-1230

2020-02-11

● If humidity rises above the setpoint (4%) before the proof timer times out, the

humidification relay does not engage and the proof timer is reset. If the humidity

rises to the setpoint, a 30-second proof timer engages. If the humidity is still above

the setpoint after the proof timer times out, the humidification relay de-energizes.

● If Parameter P320 (IND HMDTY) is set to NO (default), then the humidification

relay is not enabled unless the heating relay is energized. If Parameter P320 is set

to YES, then the humidification relay can be energized at any time, regardless of

the heating status. The fan relay is not energized by the humidification sequence.

Dehumidification

If one of the configurable digital outputs is configured for a humidification function, the

corresponding relay closes and enables a 24 Vac output signal to be transmitted to the

dehumidification device. Humidification and dehumidification relays cannot be

energized simultaneously.

● The dehumidification relay will energize when measured humidity rises

approximately 4% above the setpoint, and will de-energize when measured

humidity reaches the setpoint. Deadbands and proof timers are enforced to prevent

short cycling. The thermostat defaults to control dehumidification in Cooling mode

only.

● You must enter a humidity setpoint (HmdySp). The valid range is 10 to 90%; the

default value is 50%. If the humidity rises to 4% above the setpoint, a 30-second

proof timer engages. If the humidity is still 4% above the setpoint after the proof

timer times out, the dehumidification relay energizes.

● If the humidity drops below (setpoint + 4%) before the proof timer times out, the

dehumidification relay does not engage, and the proof timer is reset. If the humidity

drops to the setpoint, a 30-second proof timer engages. If the humidity is still below

the setpoint after the proof timer times out, the dehumidification relay de-energizes.

● If Parameter P320 (IND HMDTY) is set to NO (default), then the dehumidification

relay will not be enabled unless the cooling relay is energized. If Parameter P320 is

set to YES, then the dehumidification relay can be energized at any time,

regardless of the cooling status. The fan relay is not energized by the

dehumidification sequence.