Water To Water Unit Control Panel (Optional) | 17WW & WT Models
8733943362 (2016/08)Revised 08-16
WATER TO WATER UNIT CONTROL
PANEL (OPTIONAL)
Bosch water heat pump controller offers a low cost,
simple solution to the control of a water to water heat
pump unit. The control is configurable to provide cooling
only, heating only or auto change over control strategies
based on the application of the unit in a given system.
For models equipped for remote control see page # 8
Features:
• Selectable mode of operation. Cooling, Heating or
Auto Changeover.
• Adjustable temperature differential for heating and
cooling set point.
• Adjustable auto changeover set point with
adjustable dead band setting.
• Intelligent auto reset of a fault condition avoids
nuisance hard lockouts.
• LED display of control temperature and set points.
• ° F or ° C Display.
• 50/60 Hertz operation.
• Pump operation configurable for continuous or
cycling operation with the compressor.
• Compressor lead-lag operation on units with dual
compressors.
• Malfunction output and service LED can be set to
steady or pulsing to indicate fault condition.
• Color LED’s indication of mode of operation.
• Set point retention in non volatile memory in the
event of a power failure.
• Five minute delay on break or power interruption for
compressor short cycling protection.
• Brown out low voltage protection.
UNIT SENSORS
The unit controller is provided with two sensors:
Water sensor:
This sensor will control unit operation in the cooling or
heating mode based on the water temperature on the
load side. It may be field mounted for example on the
return water line or in a water tank when provided with
a field supplied inversion well. The location will depend
on the specific requirements of the job.
Changeover Sensor
This sensor will put the unit in either the heating or
cooling mode depending on the set point. It maybe
mounted in a location that would be indicative if the unit
should be in either the heating or cooling mode, for
example outdoors.
The sensor may be located up to 1000 feet from the unit
(additional field supplied wiring required).
MODES OF OPERATION
The controller will memorize the last mode used before
power is removed and will run in that mode after is
turned on. In all modes the control will display
temperature degree differential setting for five seconds
once it is powered and this setting for five seconds once
it is powered and this settings may be adjusted during
this time. Thereafter the display will switch to the
monitored water temperature. When switching from one
mode to another the set point (the decimal point is used
to distinguish it from water temperature) for the new
mode is displayed for 5 seconds and the monitored
water temperature. During this time the set point may be
adjusted.
OFF MODE
In the OFF MODE all outputs are disabled and mode
indication LED’s will be off.
The control will first display temperature differential
setting with the ability for the user to adjust it and then
will display “OFF” and finally water temperature.
HEATING MODE
When the unit is operated in the heating mode and the
controlled water temperature is below the set point
minus the differential setting is below the set point
minus the differential setting, terminal Y1 will close and
the unit will operate (first stage compressor in a two
stage unit). When the set point is satisfied the
compressor is turned off.
In a two stage unit after the first activation if the water
temperature drops an additional two degrees below the
set point, the second stage (terminal Y2) will be
activated (if control is configured for both
compressors). Both stages will be on until the set point
is satisfied.
When the units runs after power is applied or the mode
is changed from cooling to heating, if the fluid
temperature is below set point and does not change for
3 minutes, the second stage of heating will be activated.
This only applies for a two stage machine.
There will be 5 minutes delay on a break after the unit
cycles off on temperature, a power interruption or
because of a fault condition.
at any point in time the control will ignore a low pressure
switch condition for 120 seconds before turning off the
compressor.
COOLING MODE
When the unit is operated in the cooling mode and the
leaving water temperature is above temperature set
point plus the differential setting, terminals Y1 will close
(first stage compressor of a two stage unit) and the unit
will operate in the cooling mode. When the set point is
satisfied the compressor is turned off. The reversing
valve is always activated when the unit is in the cooling
mode.
On two stage units, after first stage activation if water
temperature increases two degrees above the set point,
the second stage (terminal Y2) will be activated (if
control is configured for both compressors). Both stages
will remain on until the set point is satisfied.
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