Specifications

22
4.3. System Operation Modes
The standard sequence of operation for a
Seresco dehumidifier is relatively simple.
Whenever the compressor operates the
evaporator coil is active where it absorbs
heat from the warm, humid air stream. The
cooling process at the evaporator coil drops
the air well below its dew point and thereby
dehumidifies the air.
 Whenever the compressor operates the
evaporator is always dehumidifying and
cooling the return air.
The heat removed from the air at the
evaporator (plus the heat of compression)
must be rejected to one of three heat sinks;
room air, pool water (PH AND PV models)
or outdoors (remote condenser/Dry
cooler/cooling tower). The microprocessor
will direct the heat to where it is needed
based on the room conditions.
In the case of PH AND PV models with
remote condensers, if both the water and
the air require heat, the dehumidifier heats
the air first. If neither the water nor the air
require heat, then the dehumidifier rejects
the heat to the Air conditioning condenser.
4.3.1 Power turned ON (or after power
failure)
 Microprocessor self test and system
diagnostics begins. If all systems are a
go, the microprocessor will use sensor
feedback to resume normal unit
operation.
 Blower begins to operate after a 60 sec
initial delay and then runs continuously.
 Microprocessor confirms with internal
real time-clock and operation log that
compressor has been off for 5 minutes.
4.3.2 Dehumidification Mode
This mode occurs when the space requires
dehumidification. The air discharged from
the unit is dehumidified and about 20F
warmer than when it entered.
 The return air Relative Humidity is
above setpoint.
 The compressor starts.
 The evaporator sees nominal airflow.
 The compressor hot gas condenses at
the reheat coil.
4.3.3 Air Conditioning Mode.
When the room air requires cooling only, the
NE unit will direct 100% the refrigerant hot
gas heat outdoors. The air discharged from
the unit is dehumidified and about 15F
cooler than when it entered.
Air Conditioning Mode Stage 1
 The return air temperature is above
setpoint.
 The compressor starts if not already
operating in dehumidification mode.
 The evaporator sees nominal airflow.
 The compressor hot gas condenses at
the outdoor air-cooled condenser.
Air Conditioning Mode Stage 2
 The return air temperature has been
significantly above setpoint for an
extended period of time.
 The compressor starts if not already
operating in Stage 1 AC or
dehumidification mode.
 The evaporator bypass damper closes
for maximum airflow across the coil.
 The compressor hot gas condenses at
the outdoor air-cooled condenser.
4.3.4 Pool Water Heating Mode (PH AND
PV Models Only)
If the unit is in dehumidification or air
conditioning mode then there is free heat
available from the dehumidifier.
 The pool water temperature drops below
setpoint.
 Water heating demand alone will not
start the compressor. There must be a
pre-existing demand to operate. If the
compressor is already operating:
o The pool water control valve
directs hot refrigerant flow through
the heat exchanger.
o The heat exchanger rejects heat
to the pool water. Operating in
pool water heating mode
increases system capacity and
efficiency.
 If there is no other demand requiring
compressor operation the
microprocessor sends an on/off signal to
the external auxiliary pool water heater
(by others). If the auxiliary pool water
heater has a separate controller, ensure
the set point is set lower or equal to pool
water setpoint on the NE control panel.
4.3.5 Blower Operation
Units have been factory wired for continuous
blower operation. This helps prevent air
stagnation and stratification. Continuous
blower operation is also required to ensure
that the sensors read conditions
representative of the entire Natatorium.