Download Print this page

System Operation; Timers And Faults; Sequence Of Operation - Bosch Greensource SM024 Installation, Operation And Maintenance Manual

Greensource cdi series sm model water-to-air heat pumps
Hide thumbs


30 | System Operation


Timers and Faults

Random Start-Up Delay
This delay prevents multiple units sharing the same
electrical circuit or network from starting at the
same time. It ensures that the Heat Pumps
connected to the same electrical circuit do not
demand a high inrush of current simultaneously
when starting up after a power failure. The random
start time delay is in the range of 200–300
seconds. In test mode, the random start time delay
is reduced to 10 seconds. Random Start-Up delay
only runs during start up or after power has been
completely removed. It does not take effect after a
brownout condition.
Test Mode
Test mode decreases all delay timers to 10
seconds. Test mode is only for testing purposes
and serves no function to the end user of the
equipment. In test mode, the alarm relay and
display relays will pulse during both soft lockout
and hard lockout. If a soft lockout alarm is cleared,
both relays will stop pulsing. The controller will
exit test mode after 20 minutes or upon a power
The test mode command can only be set via the
Bosch EasyStart app.
If the controller is set to "TEST" mode via Bosch
EasyStart app, the safety delays will be reduced
to 10 seconds. The controller will automatically
exit test mode after 20 minutes.
Anti-Short Cycle Delay (ASC)
This feature protects the compressor from short
cycling if the (Y1) call is removed and set or if a
refrigerating circuit level fault is sensed to the
point that the compressor shuts down. The ASC is
300 seconds during normal operation and 10
seconds in test mode. The ASC will not be in effect
during a Random Start-Up delay.
If the HPC is set to "TEST" mode via the Bosch
EasyStart app, the ASC delay will only be 10
8733819578 (2019/02)
Snapshot Record
The HPC constantly monitors all thermostat
sensors and thermostat demand values. The
controller also has an additional feature where the
latest fault snapshot will be saved to the
controller. When a new fault occurs the snapshot
will be saved and overwrite the previous snapshot.
The following faults in the table below will be
available in the snapshot record.
Condensate Overflow Hard Lockout Fault
Freeze Evaporator Hard Lockout Fault
Freeze Evaporator Temp Sensor Open
Freeze Evaporator Temp Sensor Open
High Leaving Water Temperature Fault
Freeze Evaporator Soft Lockout Fault
Table 5
Available Fault Snapshots

Sequence of Operation

Cooling Mode
Energizing the "O" terminal energizes the unit
reversing valve thus placing the unit into cooling
mode. The fan motor starts when the "G" terminal
is energized.
The fan motor will take 30 seconds to ramp up
to operating speed and will run at fan-only rated
air flow as long as there is no call for compressor
or heater operation.
Subject to change without prior notice
Greensource CDi Series SM
Available Fault Snapshots
High-Pressure Hard Lockout Fault
Low-Pressure Hard Lockout Fault
Freeze Coaxial Hard Lockout Fault
Brownout Voltage
Freeze Coaxial Temp Sensor Open
Fan Motor Hard Lockout Fault
Fan Motor Soft Lockout Fault
Freeze Coaxial Soft Lockout Fault
High-Pressure Soft Lockout Fault
Low-Pressure Soft Lockout Fault
Greensource CDi Series SM Model

Hide quick links: