Heat Pump Controller
Heat Pump Controller
8733819577 (2019/02)
Subject to change without prior notice
12
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System Operation
Dehumidification
During cooling operation only, if the controller
senses a signal on the (H) terminal of the
thermostat interface block the fan CFM output will
be reduced by 15% (adjustable). The fan CFM
reduction percentage is adjustable from 15% to
40% reduction from nominal via the Bosch
EasyStart app.
Latching Mode Operation
The latching feature enforces how a HPC stages
down the multiple stages of heating and cooling. A
WSHP condenser coil uses water as medium for
exchanging heat with the refrigerant. Controlling
the stage down process will result in benefits to
the performance and efficiency of the system. As
the name implies, the maximum demanded stage
is latched on until the thermostat is satisfied at
which time all heating or cooling calls are
terminated. Many thermostats are designed for Air
Source appliances and the medium for exchange
(air) can usually provide heat exchange; however,
for ground loops used in WSHP can become
saturated after long run times. Latching is used in
WSHP applications as a means to “rest” the
ground loop between cooling and heating cycles
thus increasing the capacity for heat exchange.
Performance, efficiency, and comfort provided by
a WSHP will largely be maintained by preventing
the degradation of the loop’s physical heat
exchange properties.
During latching mode operation, the unit will
fasten the two compressor outputs together until
the demand is satisfied. If the thermostat removes
the second-stage demand, the HPC will keep the
second stage of compressor enabled until demand
is satisfied.
Unlatching Mode (Factory Default)
During unlatching mode the unit will cycle the
compressor outputs according to the thermostat
demand. The unit will downstage from second-
stage compression to first stage when the demand
for second stage is dropped by the thermostat (Y2
and Y1 call to only Y1 call).
In case of DWT/DRT sensor failure, the HRP
operation will be disabled.
NOTICE
: Keep the HRP configuration setting
set to disabled if there is no domestic water
supply available.
WARNING
: Before performing service or
maintenance operations on the system, turn
off the main power to the unit. Electrical
shock could cause personal injury or death.
The controller has a minimum 270 CFM/Ton
requirement. The controller will not allow the
CFM/Ton to fall below this minimum even If the
reduction percentage calls for a lower CFM/Ton
amount.
