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8
TW Series / Water to Water
*A water-to-water series Heat Pump/Liquid Chiller
can be utilized for direct pool/spa heating without a
secondary heat exchanger. In this application
cupro-nickel heat exchangers must be used.
Automatic chemical feeders must never be installed
up stream of the unit. An external bypass should be
installed to avoid over-flowing the heat exchanger
to prevent coil erosion. The pool pH levels and
chemical balances must be maintained to avoid
possible heat exchanger damage.
WaTer To WaTer unIT ConTroller
(opTIonal)
Bosch's water to 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.
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 adjust-
able 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.
6 720 220 047
Water to Water unit Controller
• Brown out low voltage protection
All of the unit's safeties are tied back into the
controller for system 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 immersion 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 may be 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 it is turned on. In all modes the control will
display temperature degree differential setting for five
seconds once it is powered and this setting 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 then 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, terminal Y1 will
close and the unit will operate (first stage
Subject to change without prior notice
Revised 03-11
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