Quest IQ Compressor Wall OMM
18
September 2020
•
Based on the premise air temperature, the Reheat and AC valves would adjust their opening position (open
more/close more), reducing or increasing fluid flow to and through the respective fluid coils:
Reheat and AC valves are controlled in the same manner with opposite effect: for example,
when AC valve opens 10% more, Reheat valve closes 10% more etc.
o
if more heat is required by the room air, the Reheat valve opens more, and AC valve closes more, thus
diverting more fluid to the reheat coils (heat is rejected to the premise);
o
if more cooling is required by the room air, the AC valve opens more, and Reheat valve closes more,
thus diverting more fluid to the dry cooler (heat is rejected outdoors).
o
Outdoor dry cooler fans are engaged only if at least some fluid is diverted towards outdoor dry cooler
and compressor pressure is higher than pre-set level (see
Outdoor Dry Cooler Operation
below).
•
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 glycol pump and
compressor stop.
Outdoor Dry Cooler Operation.
Respective signal(s) are sent by control system to engage EC-type fans via a variable 0-10VDC signal (proportional
to the compressor head pressure level). Refer to the wiring diagram if/when needed.
If the dry cooler is equipped with the built-in pump package (to establish cooling fluid flow between HVAC system
and the dry cooler or to serve as additional/booster pump), the said pump is also engaged along with dry cooler
fans
–
pump would stay engaged while fans are engaged (regardless of the fans’ speed
).
Economiser Option (Eco-Coil).
HVAC system, equipped with eco-coil and dry cooler, can take an advantage of economiser option and use outdoor
air to cool the premise without resorting to compressor operation.
•
When Air Conditioning (cooling) mode is requested and outdoor air conditions warrant (outdoor air and,
respectively, cooling media in the dry cooler are cool enough), ECV (eco-coil mixing valve) would divert
cool media from dry cooler into eco-coil, thus cooling recirculating air without running the compressor.
