User Manual

Sequence of Operation
Auxiliary Sequences
18
Siemens Industry, Inc.
Application Note, App 14900
140-1231
2020-02-11
● If humidity rises above (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 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
will not be 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 setpoint, and will de-energize when measured humidity
reaches 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 setpoint, a 30-second proof
timer engages. If the humidity is still 4% above 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 setpoint, a 30-second proof timer engages. If the humidity is still below
setpoint after the proof timer times out, the dehumidification relay de-energizes.
● If Parameter P320 (IND HMDTY) is set to NO (default), 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.