Diagnostic functional operation
Defect
frequency
confirmation
Overheat protection operation
When the thermostat of the backup heater
activates during the operation of the heat pump
or backup heater. When the thermostat
operation is activated while it has been stopped.
1. No water (heating without
water) or no water flow.
2. Defect of the flow switch.
3. Defect of the backup heater
(poor automatic reset thermostat).
Antifreeze operation (2)- cooling mode only
When TC + TWO < -15°C
1. Almost no water flow
2. Defect of the flow switch
3. Low refrigerant charge
Operation of the release protection
When the TWO release counts to 10.
1. Almost no water flow.
2. Defect of the flow switch.
3. Check the water outlet
temperature sensor (TWO).
Heating, hot water heater
The antifreeze control is detected under the
condition of TWI<20°C while TWI>15°C,
TTW>20°C is not detected after the heater
backup.
1. Activated by a large load of
heating or hot water supply.
2. Check the heater power circuit
(backup or hot water cylinder
heater). • Power supply voltage,
breaker, power supply connection
Regular communication error between hydro
unit and remote controller
When there is no regular communication from
the remote control for 3 min, or when no remote
control is equipped.
1. Check remote control
connection. 2. Defect in the
remote control.
Regular communication error between hydro
unit and outdoor unit
The serial signal cannot be received from
outdoor.
1. Check the serial circuit. •
Miswiring of the crossover
between the water heat
exchanger and the outdoor unit
TC sensor error
Open or short circuit in the heat exchange
temperature sensor.
1. Check the resistance value and
connection of the heat exchange
temperature sensor (TC).
TWI sensor error
Open or short circuit in the water inlet
temperature sensor.
1. Check the resistance value and
connection of the water inlet
temperature sensor (TWI).
TWO sensor error
Open or short circuit in the water outlet
temperature sensor.
1. Check the resistance value and
connection of the water outlet
temperature sensor (TWO).
TTW sensor error
Open or short circuit in the hot water cylinder
sensor.
1. Check the resistance value and
connection of the hot water
cylinder sensor (TTW).
TFI sensor error
Open or short circuit in the floor temperature
sensor.
1. Check the resistance value and
connection of the floor-inlet
temperature sensor (TFI).
THO sensor error
Open or short circuit in the heater outlet
temperature sensor.
1. Check the resistance value and
connection of the heater outlet
temperature sensor (THO).
Detection of THO disconnection error
When TWO–THO>15K is detected and 30 sec
elapsed.
1. Check for any disconnection of
the heater outlet temperature
sensor (THO).
TFI sensor error
When TWO–TFI>30K is detected and
TFI<TWI–5K is detected.
1. Check the connection of the
floor-inlet temperature sensor
(TFI).