– 57 –
Hydro Unit
Installation Manual
A03
Temperature increase
error
(hot
water supply)
(TTW)
Heating
O
Hot water
×
O
1. Check the hot water cylinder sensor (TTW).
2. Check the hot water cylinder thermal cut-out.
A04
Antifreeze operation
O
×
1. Almost no or little water flow.
• Dirt clogging in the water piping system.
• The water piping is too long or too short.
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 and Flow Switch.
A05
Piping antifreeze operation
O
O
1. Check 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.
A07
Pressure switch 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 high pressure switch.
5. Failure of a refrigerant value to open.
A08
Low pressure sensor operation
error
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.
4. Defect in the low pressure sensor.
5. Check the refrigeration cycle (gas leak).
A09
Overheat protection operation
(Thermostat of the backup heater)
Heating
×
Hot water
O
×
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).
A10
Antifreeze operation 2
O
×
1. Almost no or little water flow.
2. Check the water inlet, water outlet and heat exchange
(TWO, TC) sensors.
A11
Operation of the release protection
Heating
Cooling
×
Hot water
O
×
1. Almost no water flow.
2. Defect of the flow switch.
3. Check the water outlet temperature sensor (TWO).
A12
Heating, hot water heater error
O
O
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
O ... Possible
× .... Not possible
Check
code
Diagnostic functional operation
Determination and action
Operational cause
Backup
operation
Automatic
reset
57-EN
Summary of Contents for HWS-1405XWHM3-E
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