Chapter E - Sequence Of Operation; Set Points E; Ventilation E; Purge Option E - Seresco NP Series Operation And Maintenance Manual

Sequence of Operation
The dehumidifier's ventilation system establishes the required airflow through the dehumidifier. The control
system compares air temperature and humidity to their desired values (set points) and proceeds to dehumidify,
cool or heat the recirculating air.
If the dehumidifier is equipped with the pool water heating option, the pool water temperature is compared to its
set point and pool heating is provided if required.
Set Points
The control system is constantly adjusting unit operation to achieve and maintain said parameters within couple
degrees/percent of the set point.
Refer to the dehumidifier's main label for the design value of control parameters, as well as the following note.
Note:
To ensure the dehumidifier's most economical operation, we recommend maintaining the following
relationship between pool water and room air temperatures:
Ventilation.
The main blower runs continuously, establishing required. The main blower speed is pre‐set via adjustable variable
signal.
Minimum Exhaust Fan (EF), if dehumidifier is equipped with such option, directs portion of return air outdoors.
Like main blower, exhaust fan(s) speed is also controlled via adjustable (pre‐set) variable signal, that varies based
on scheduled ventilation mode (Occupied, Non‐Occupied and Spectator) or call for Economiser Mode (as part of
Air Conditioning and/or Dehumidification operation).
Minimum Outdoor Air (OA) damper, if dehumidifier is equipped with such option, opens to introduce fresh
outdoor air into the premise. OA damper could be equipped with ON/OFF (simple fully open – fully closed) or
modulating‐controlled actuator; latter one would be controlled same way as minimum exhaust fan.
Purge (Additional Exhaust) Option.
Along with Min Exhaust Fan and Min Outdoor Air damper, dehumidifier could have additional set of exhaust
(purge) fan(s) (PF) and purge outdoor air damper (POA), commonly referred as Purge. Purge fan(s) and OA
damper(s) function is to allow for higher exhaust and fresh air amount, up to complete (100%) air changeover
(when all exhaust fans and OA dampers are at their max capacities).
Purge Fan(s) and Purge Outdoor Air damper(s) are controlled in the same fashion as min exhaust fans and min
outdoor air. Some dehumidifiers may be equipped with additional Return Air damper: it closes in event of
complete air changeover, separating return air side of dehumidifier from supply side (refer to Layout and
Components chapter, as needed, for respective devices' location).
Complete air changeover, triggered manually, is known as Purge Mode.

Note. Externally installed Exhaust Fan(s) and Outdoor Air damper(s) could be also controlled by the
dehumidifier control system. This applies to both, Minimum and Purge/Additional, fans and dampers.
OMM.E.S.AA.01
E – Sequence of Operation
Room Air T = Pool Water T + 2˚F
1
E‐ February
2020