56
Hydro Unit check codes
o…...…. Possible
x…. Not possible
Check
code
Diagnostic functional operation
Determination and action
Defect
frequency
confirmation
Operational cause
Backup
present
Automatic
reset
A01
Pump or flowing quantity error
1) Detected by TC sensor TC 63°C is detected
in the heating or hot water supply heat pump
operation (except for defrosting).
×
×
1. Almost no or little water flow. •
Not enough vent air • Dirt clogging
in the water piping system. • The
water piping is too lon
g. •
Installation of buffer tank and
secondary pump
4
2) Detected by flow switch abnormality When no
signal of the flow switch is showing 2 min after
the built-in pump operation started.
2
3) Detection of chattering abnormality in the
flow switch input Chattering detection: Detects
input changes (OFF
⇔
ON) 4 times within 10
seconds during operation.
4
4) Disconnection of the flow switch connector
When the stopped built-in pump starts its
operation, the flow switch status is detecting
"water flow".
1. Disconnection of the flow switch
connector.
2. Defect of the flow switch.
2
A02
Temperature increase error
(heating)
When one of the TWI, TWO and THO sensors
exceeds 70°C.
Heating O
Hot water ×
O
1. Check the water inlet, water
outlet and heater outlet (TWI,
TWO, THO) sensors.
2. Defect of the backup heater
(defect automatic reset
thermostat).
1
A03
Temperature increase error
(hot water supply)
When the TTW sensor exceeds 85°C.
Heating O
Hot water ×
O
1. Check the hot water cylinder
sensor (TTW).
2. Check the hot water cylinder
thermal cut-out.
1
A04
Antifreeze operation (1)
1)TWO>20°C condition: 2×TC+TWO < -12°C is
detected.
2)TWO 20°C condition: TC+TWO < 4°C is
detected.
3)TWI 10°C is detected during defrosting.
O
×
1. Almost no or little water
flow. •
Dirt clogging in the water piping
system. • The water piping is too
long.
2. Check the heater power circuit. •
Power supply voltage, breaker,
power supply connection
3. Set the presence of the backup
heater.
4. Check the water inlet, water
outlet and heat exchange (TWI,
TWO, TC) sensors.
Heating 8
Hot water 8
Cooling 4
A05
Piping antifreeze operation
Activating the heater under the condition of
TWO<4orTWI<4orTHO<4 does not achieve
TWO,TWI,THO 5°C after 30 min elapsed.
O
O
1. Ch
eck the heater power circuit. •
Power supply voltage, breaker,
power supply connection
2. Check the water inlet, water
outlet and heater outlet sensors
(TWI,. TWO, THO).
3. Disconnection of the backup
heater.
1
A07
Pressure switch operation
The pressure switch operates for 300 sec
continuously during the heat pump operation.
O
×
1. Almost no or little water flow.
2. Defect of the flow switch.
3. On-load operation under the
above conditions.
4. Defect in the pressure switch.
1
A08
Low pressure sensor operation error
The low pressure sensor detected 0.2 MPa or
less.
O
×
1. Almost no or little water flow.
2. Defect of the flow switch.
3. On-load cooling or prolonged
defrosting (a lot of frost formation)
under the above conditions.
8
4. Defect in the low pressure
sensor.
8
