8.3.1 Backup heater in Replacement mode
The Backup heater is activated for space Heating or DHW (in the latter case, only if no dedicated DHW tank heater
is fitted) to replace the compressor, if the compressor is unable to meet demand as it has shut down for one of the
fo llowing reasons:
HP unit stopped (according of operating limits)
Probe faults (see lists below)
For heating system water production, the Backup heater will be controlled using the same control as the
compressor in Heating mode.
For DHW production, aiming to reach the “Comfort or Economy” set point.
However the manual mode can also be selected, setting Par4600=2 (Emergency), the water will only be heated
using the Backup heater, disabling compressor operation. This mode is typically used in the event of compressor
faults.
The Backup heater will be activated as described below:
When probe faults occurred, The Backup heater is activated for;
Error code/name
Heating
DHW
P3
Refrigerant High Pressure switch Failure
ON
ON
FU
Refrigerant High Pressure switch Operation
ON
ON
A6
Sensor (temp. Suction)
ON
ON
A7
Sensor (temp. Defrost)
ON
ON
A8
Sensor (temp. Discharge)
ON
ON
E5
Sensor (temp. Return water)
ON
ON
L1
Sensor (temp. DHW tank)
ON
OFF
L3
Sensor (temp. Buffer tank)
OFF
ON
L4
Sensor (temp. Mixed water)
OFF
ON
L5
Sensor (Humidity)
OFF
ON
L8
Sensor (temp. Room air, Master Remote controller)
OFF
ON
L9
Sensor (temp. Room air, Slave Remote controller)
OFF
ON
(5.0°C)
Manual water set point
(50.0°C)
Water temperature
hysteresis
Water temperature
Backup heater ON
OFF
110
8. Domestic Hot Water Production
Summary of Contents for AEYC-0639U-CH
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