14
Sequence of Operation Time Line
Referenced Notes (See pages 11 & 12)
1) See “Using the Control Panel” for a listing of valid
modes that may occur during “Unit is Running.”
2) Upon power up, refrigerant dilution valve 1 (RDV1)
remains off for thirty seconds.
3) Model ABDA Only - For the specific flame safeguard
sequence see the appropriate burner literature.
4) When a “need to cool” exists, an incomplete dilution
cycle can be exited by pressing the Auto key. The chiller will
proceed with a new startup sequence.
5) The “Auto, waiting for a need to cool” can be exited by
pressing Stop.
6) Power loss at this point will result in a dilution cycle
upon re-establishing power, if there is no need to cool.
7) Power loss at this point will result in the remainder of a
dilution cycle being completed upon re-establishing power.
8) Chilled water pump will be stopped after the dilution
cycle is completed for all Machine Shutdown Auto Reset
and Machine Shutdown Manual Reset except in the case of
chilled water pump flow overdue where the chilled water
pump signal remains on.
9) Panic stop; operator presses the stop key twice within 5
seconds. This state may be exited by pressing either the
stop or auto key.
Startup/Shutdown
Startup Pre-heat
Solution pumps are started before energy is input.
The controls execute a pre-heat sequence upon startup to
establish an adequate concentration level before releasing
to closed loop control. Pre-heat sequence consists of the
energy input command held at a reduced rate. (40%) until
the Lithium Bromide solution concentrations reach 54%.
Service Tests: Manual energy input is allowed during this
pre-heat sequence.
Control of Leaving Water Temperature and concentration
are overridden.
Limits and safeties are active.
Shutdown Dilution Cycle
When the chiller cycles OFF a dilution cycle mixes the
strong lithium bromide solution with refrigerant water to
reduce solution concentrations and minimize the potential
for solution crystallization. The dilution cycle is performed
on all shutdown modes with one exception. The exception
is a “Panic Stop” which consists of an operator depressing
the stop key twice) within a 5 second period. This will stop
the machine without the normal dilution cycle. A restart can
be initiated at anytime by pressing the auto key. A dilution
cycle is initiated by pressing the stop key.
Terminating the energy input, opening the refrigerant
dump valve, and running the solution pump for 3 to 15
minutes dilutes the solution. This dilution cycle duration is
determined by the solution temperature when the dilution
sequence is initiated.
The refrigerant valve (RDV1) dumps refrigerant from the
evaporator into the absorber on command to dilute the
lithium bromide solution. This action occurs when a
dilution cycle or safety shutdown is initiated by the
machine control.
Dilution Time
Less than 158°F
Less than 200°F
3 minutes
Greater than or
Greater than or
15 minutes
Equal to 150°F
Equal to 200°F
Solution Temperature Leaving High
Temperature Generator (HTG)
Solution Temperature Leaving LT6 +