September 2020 27 Dectron DS Series – Outdoor OMM
Compressor(s)
Whenever the compressor operates, the evaporator is always dehumidifying and cooling the return air. The heat
removed from the air at the evaporator, as well as the heat from the compressor's action, must be rejected to one
of three heat sinks: room (premise) air, pool water (if applicable) or outdoors. The control system will direct the
heat to where it is needed based on room (air and pool water temperature) conditions:
• If room air is needed to be warmed up – more heat is diverted towards reheat coil;
• If pool water is needed to be warmed up – more heat is diverted towards pool heating coaxial heat exchanger
(if dehumidifier is equipped with this option).
• Rest of the heat (if any) is diverted towards outdoors (outdoor condenser, fluid cooler, etc.)
Compressor Circuit Operation
Piping schematic for compressor circuit is shown on Pic. E.2.
When a demand requires the compressor to operate, the following sequence occurs:
• Once blower operation, related safeties and timers are confirmed by the control system, the pump down
solenoid valve opens and once pressure stabilizes, the compressor starts.
• Based on the premise air temperature, the refrigeration reheat and/or AC solenoid valve opens, allowing
refrigerant to flow through the respective condenser:
o if more heat is required by the room air, the reheat solenoid valve opens (heat is rejected to the
premise); if more cooling is required by the room air, the AC solenoid valve opens (heat is rejected
outdoors (via outdoor condenser or plate heat exchanger).
o Outdoor condenser or fluid cooler fan is engaged only if hot gas is diverted outdoors and compressor
pressure is higher than pre-set level (see Outdoor Condenser and Fluid Cooler Operation below).
• Dehumidifiers, equipped with pool water heating option, also engage the refrigeration pool water heating
solenoid valve to reject heat into the pool water, based on pool water temperature.
• Once demand for the compressor’s operation is removed (respective call is satisfied), the pump down solenoid
valve closes; once the compressor suction pressure reaches the pre-set pressure, the compressor stops.
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