Quest IQ Dry Cooler OMM
8
September 2020
Control
There may be some different types of controls used with NG series dry coolers.
Fan type
:
•
Modulating
(EC-type) fans are capable of varying their speed (from 0 to 100%) based on 0-10VDC signal.
Control Type
(all control types referenced below are applicable to all fans type described above):
•
Externally controlled
Dry cooler. Fan(s) speed signal (modulating) is provided from external system (usually
–
the one that dry cooler serves, to satisfy said system operational requirement). This is typical for dry cooler
serving single systems. Typical signal type for this control type are modulating (0-10VDC). It may control the
fan according to head pressure or another control method chosen by installer.
•
Self-controlled
(“stand
-
alone”) Dry cooler. Fan(s) speed signal
(modulating) is based on built-in control device.
Most commonly used one is an aquastat, monitoring temperature of the cooling media (water/glycol mixture),
leaving the dry cooler.
o
Typically, aquastat is pre-set to maintain entering cooling media temperature at certain level: the
sensor issues the signal to start the fan(s) and increase their speed as temperature increases (and,
respectively, reduce fans’ speed when temperature reduces). Typically, this signal is 0
-10vdc
–
it
could be accepted by EC-type fans directly.
Dry cooler is normally provided with the wiring diagram, depicting its specific control schematic
–
refer to it as
needed.
