Bosch TW Series Installation And Maintenance Manual page 10

10 TW Series / Water to Water
or reoccurs within the next 60 minutes, the unit will
go into a hard lockout and requires a manual
lockout reset. During this period the fault LED will
indicate the cause of the fault.
A 120 second time delay is built into the low
pressure switch to avoid nuisance trips with low
fluid temperatures.
While in a soft lockout condition the display will
show the specific fault (for example LP1) and the
"service" LED will turn on according to the
malfunction mode. If the setting for malfunction
mode is "steady," the service LED will turn and
remain on. If the setting is "pulse," the service LED
will blink according to the blink code as follows:
broWnouT proTeCTIon
The control will disable all outputs if the supply
voltage drops below 17 VAC. The outputs will be
enabled if the supply voltage rises and remains
above 17 VAC for the 5 minutes time delay. During
that time control will display "bro."
Manual loCkouT
blink Code
One blink
Two blinks
Three blinks
Four blinks
The unit or refrigeration circuit will go into a manual
lockout if the HPS or LPS opens (LPS open more
than 120 seconds each time) twice within one hour.
During manual lockout the compressor(s) is turned
off and locked out and the display will show the
fault (for example LP1) and the "service" LED
"malfunction" output will either be steady or blink
according to the malfunction mode as described
above.
If selection for compressor is "Du" (see
configuration) and one compressor has locked out,
the control will switch the call to the other
compressor. If compressor setting is "Si", the
control shall not switch the call to the other
compressor.
To reset a unit after a hard lockout the user needs
to recycle power or switch the controller to the
OFF mode.
6 720 220 047
fault Condition
High pressure circuit 1
Low pressure circuit 1
High pressure circuit 2
Low pressure circuit 2
Subject to change without prior notice
brownout protection
lead-laG
(noT To be uSed WITH TW unITS)
The Controller has the capability to lead-lag
compressors on a dual compressor unit.
The lead-lag between the compressors is active
only when both compressors are in use (and the
compressor setting is "Du").
When the setting for lead-lag is other than 00,
compressor setting is "Du" and one compressor
has locked out; control will switch the call to the
other compressor and stop the timing for lead-lag.
The lead lag setting remains in the memory.
If control has called for the second stage three
times in a row, and compressor setting is "Du";
regardless of the lead-lag setting control will switch
the call to the other compressor. The lead-lag timer
is reset and the lead-lag setting still applies.
puMp CyClInG
When ordered with the optional pump relay the
controller will cycle either the load, source or both
pumps with the compressor operation. Please see
the typical wiring diagram for details.
operaTInG InSTruCTIonS
Please refer to Figure #4.
user Interface:
The following parameters are displayed on the
screen:
• Control fluid temperature when in normal mode
• Settings within the configuration mode
• Individual operating mode temperature set points
• Fault display
up button:
• Press once to display the current set point tem-
perature.
• After current set point temperature is displayed,
pressing again will increment the set point 1
degree for every push. Pressing and holding the
Revised 03-11