Bosch TW Series Specifications download pdf (Page 10)

Subject to change without prior notice Revised 03-11

6 720 220 047

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

uid temperatures.

While in a soft lockout condition the display will

show the specic 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 Fault Condition

One blink High pressure circuit 1

Two blinks Low pressure circuit 1

Three blinks High pressure circuit 2

Four blinks Low pressure circuit 2

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

conguration) 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.

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 uid temperature when in normal mode

• Settings within the conguration 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

Brownout Protection

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Bosch TW Series Specifications Page 10

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