Installation, Start-Up, Adjustment and Maintenance Manual
9
DESCRIPTION OF THE CHILLER OPERATIONS
All chiller functions and operations are monitored and controlled by the electronic control board.
The temperature probes, placed on the system in order to monitor the operation of the chiller, are
transferring the following operating temperatures to the electronic control board:
-
outlet chilled water temperature
-
inlet chilled water temperature
-
ammonia outlet temperature from condenser
-
external ambient temperature
-
generator temperature
Furthe
r control of the chiller’s operation is carried out by:
-
high temperature limit switch
-
high pressure limit switch
-
water flow switch
-
differential air pressure switch
-
chilled water thermostat
-
hydraulic pump rotation probe
To control the startup of the chiller, it is necessary to install a
control
switch (not included with the
unit)
. The switch can be a programmable timer, room thermostat or any other type of on/off switch.
The installer must do installation of this switch
. Approximately 1 second after the control switch is
closed, the electronic control board will start the hydraulic pump, condenser fan and water pump (if
controlled by the board). Simultaneously, the electronic control board will energize the oil burner if
using oil for fuel or the ignition control box if using LP or natural gas. Using LP or natural gas the
ignition control box will check the differential air pressure switch’s status and then start the ignition
sequence. The premixer motor will then start.
Used Oil (Primary):
Assuming Oil Pre-heater has established set-point temperature, the Oil Primary
will energize the burner blower motor, fuel valve, igniter circuitry, and on-burner air compressor at
which time a flame is established. The chiller is then in normal operation.
Natural Gas (Secondary):
After a 15-second purge period, the ignition control box will energize the
ignition transformer and dual gas valve simultaneously. The ignition transformer sends a high voltage
current through the igniter to generate a spark igniting the fuel-air mixture at the burner. When flame
is established, the flame sensor signals that fact to the ignition control and the ignition control stops
the spark. The chiller is then in normal operation.
After the burning device has established a flame, The Display of the electronic control board, during
the normal operation, shows in alternative mode the following information:
Water inlet temperature (after the symbol
)
Water outlet temperature (after the symbol )
Temperature difference ΔT (after the symbol
)
Used Oil:
de-energize the transfer relay which will shut down the Oil Primary causing the oil burner to
shut off.
Natural Gas:
shutdown the ignition system (i.e. the dual gas valve will close and the premixer motor
will stop). The gas burner shuts off.
And 215 seconds later the hydraulic pump, condenser fan and water circulator contacts on the
electronic control board open stopping the hydraulic, fan and water pump motors. These motors are
ran for the 215 seconds to assure that solution is returned to the generator, residual cooling in
evaporator is used and the unit is made ready for the next operating demand.
