List of error codes for the Daikin Altherma 3 ECH²O air-to-water heat pump

List of error codes for the air-to-water heat pump – Daikin Altherma 3 ECH²O

EHSX(B)04P30D
EHSX(B)04P50D
EHSH(B)04P30D
EHSX(B)08P30D
EHSX(B)08P50D
EHSH(B)08P30D
EHSH(B)08P50D

Download the Daikin Altherma 3 ECH²O manual

Fault detection and troubleshooting

The indoor unit’s electronics signal an error through a red status display light, the appearance of the error screen, and the error symbol shown on the startup screen.

Troubleshooting: error code E90XX

An error reset can be performed. If the error reappears shortly afterward, a technician must identify and fix the root cause. In the meantime, a backup mode may be maintained if applicable.

Troubleshooting: other error codes

A technician must identify and fix the root cause of the error. In the meantime, a backup mode may be maintained if applicable.

Possible malfunctions

Malfunction	Possible cause	Possible solution
Heating is not warming enough	Water flow too low.	▪ Check that all shutoff valves in the water circuit are fully open. ▪ Check whether the water filter is clogged. ▪ Check whether the expansion tank is faulty. ▪ Fully bleed the air from the heating system and the unit’s internal circulator pump. ▪ Check on the controller (“Info” menu) that sufficient water pressure is available (> 0.5 bar); top up the heating water if needed. ▪ Make sure the hydraulic circuit’s resistance isn’t set too high relative to the pump (see Chap. 10).
	Desired value ranges set too low.	In [→ Main menu → Configuration → Heating]: ▪ Increase the [Slope] parameter. ▪ Increase the [HZU max. temperature] parameter. ▪ Increase the [Max. flow temperature] parameter.
	Flow temperature control based on the active temperature.	▪ Check the [Heating mode heat limit] and [Slope] parameters in [→ Main menu → Configuration → Heating].
	Optional Backup-Heater (EKBUxx) or alternative supplementary heater not switched on.	▪ Check the power supply to the Backup-Heater (EKBUxx). ▪ The Backup-Heater’s thermal cutout (temperature limiter) has tripped. Reset it. ▪ Check the [External heat source config], [External output stage 1] and [External output stage 2] parameters [→ Main menu → Settings → Ext. source].
	The amount of water in the heating system is low	▪ Check the pre-charge pressure in the expansion tank and the water pressure; top up the heating water and adjust the pre-charge pressure if needed (see Chap. 7.2.2).
	Domestic hot water production is putting too much strain on the heat pump’s output.	▪ Check the [External heat source config] parameter settings [→ Main menu → Settings → Ext. source]. ▪ Check the [External DHW output] parameter settings [→ Main menu → Settings → Ext. source].
Hot water isn’t heating up	Domestic hot water production is switched off (e.g., the schedule is in a temperature setback phase, or the domestic hot water parameter is set incorrectly).	▪ Check the operating mode setting. ▪ Check the demand parameters.
	The tank charging temperature is too low.	▪ Increase the desired hot water temperature.
	Draw-off flow rate too high.	▪ Reduce the draw-off flow rate, limit the flow.
	Heat pump output too low.	▪ Check the room heating and domestic hot water schedules for overlaps.
	The amount of water in the heating system is low.	▪ Check the pre-charge pressure in the expansion tank and the water pressure; top up the heating water and adjust the pre-charge pressure if needed.
	Optional Backup-Heater (EKBUxx) or alternative supplementary heater not switched on.	▪ Check the power supply to the Backup-Heater (EKBUxx). ▪ The Backup-Heater’s thermal cutout (temperature limiter) has tripped. Reset it. ▪ Check the [External heat source config], [External output stage 1] and [External output stage 2] parameters [→ Main menu → Settings → Ext. source].

Malfunction	Possible cause	Possible solution
Room cooling isn’t cooling	Water flow too low.	▪ Check that all shutoff valves in the water circuit are fully open. ▪ Check whether the water filter is clogged. ▪ Check whether the expansion tank is faulty. ▪ Fully bleed the air from the heating system and the unit’s internal circulator pump. ▪ Check on the controller [→ Main menu → Info → Overview → Syst P] that sufficient water pressure is available (> 0.5 bar); top up the heating water if needed. ▪ Make sure the hydraulic circuit’s resistance isn’t set too high relative to the pump (see Chap. 10).
	“Cooling” switched off (e.g., the room thermostat is calling for “Cooling,” but the schedule is in a setback phase, or the outdoor temperature is too low).	▪ Check the operating mode setting. ▪ Check the demand parameters. ▪ Check the date, time, and schedule set on the controller.
	The refrigerant compressor isn’t running.	▪ If an optional Backup-Heater (EKBUxx) is installed: ▪ Check that the return temperature is being raised to at least 15 °C by the Backup-Heater (if the return temperature is low, the heat pump first uses the Backup-Heater to reach at least this minimum return temperature). ▪ Check the power supply to the Backup-Heater (EKBUxx). ▪ The Backup-Heater’s thermal cutout (temperature limiter) has tripped. Reset it.
	The system is in “Heating” operating mode.	▪ Switch the mode to “Cooling.”
	Outdoor temperature < 4 °C	▪ The heat pump has automatically switched to “Heating” mode to ensure frost protection if the outdoor temperature keeps dropping. No room cooling is possible.
Cooling output too low in room cooling mode	Water flow too low.	▪ Check that all shutoff valves in the water circuit are fully open. ▪ Check whether the water filter is clogged. ▪ Check whether the expansion tank is faulty. ▪ Fully bleed the air from the heating system and the unit’s internal circulator pump. ▪ Check on the controller [→ Main menu → Info → Overview → Syst P] that sufficient water pressure is available (> 0.5 bar); top up the heating water if needed. ▪ Check whether the resistance in the water circuit is too high for the pump.
	The amount of water in the heating system is low.	▪ Check the pre-charge pressure in the expansion tank and the water pressure; top up the heating water and adjust the pre-charge pressure if needed.
	Refrigerant quantity in the heating system too low or too high.	▪ Determine the causes behind too little or too much refrigerant in the refrigerant circuit. ▪ If the refrigerant quantity is too low, check the refrigerant circuit for leaks, repair it, and top up the refrigerant. ▪ If the refrigerant quantity is too high, recover the refrigerant and refill the system with the correct amount.

Malfunction	Possible cause	Possible solution
The unit’s internal circulator pump makes excessive operating noise	Air in the water circuit.	▪ Fully bleed the air from the heating system and the unit’s internal circulator pump.
	Vibration-related noise occurring.	▪ Check that the indoor unit, its components, and covers are securely fastened.
	Damage to the internal circulator pump’s bearings	▪ Replace the unit’s internal circulator pump.
	Water pressure too low at the pump inlet.	▪ Check on the controller [→ Main menu → Info → Overview] that sufficient water pressure is available (> 0.5 bar). ▪ Check that the pressure gauge is working correctly (connect an external pressure gauge). ▪ Check the pre-charge pressure in the expansion tank and the water pressure; top up the heating water and adjust the pre-charge pressure if needed.
The safety pressure relief valve is leaking or permanently open	The expansion tank is faulty.	▪ Replace the expansion tank.
	The water pressure in the heating system is too high.	▪ Check on the controller [→ Main menu → Info → Overview] that the water pressure is below the indicated maximum pressure. If needed, drain water until the pressure is within the allowed mid-range.
	The safety pressure relief valve is stuck.	▪ Check the safety pressure relief valve and replace it if needed. ▪ Turn the red knob on the safety pressure relief valve counterclockwise. If you hear a clicking noise, the safety pressure relief valve must be replaced.

Error codes

Code	Component/designation	Error	Possible troubleshooting
E75	Flow temperature sensor tv_, _BH	Flow temperature sensor error	Faulty flow temperature sensor. ▪ Check, replace.
E76	Tank temperature sensor t_DHW1	Tank temperature sensor error	Tank temperature sensor t_DHW1 or connecting cable faulty or not connected. ▪ Check, replace. ▪ Check the [DHW temperature sensor] setting.
E81	RoCon BM2C board	Communication error	Unable to write parameters to the EEPROM. ▪ Contact a technician.
E88	RoCon BM2C board		Unable to write parameters to the external Flash memory. ▪ Contact a technician.
E91	Connected CAN modules		A CAN module’s bus ID is assigned twice; assign a unique address.
E128	Return temperature sensor t_R1	Return temperature sensor error	Return temperature sensor t_R1 in the FLS flow meter or connecting cable faulty. ▪ Check, replace.
E129	DS pressure sensor	Pressure sensor error	DS pressure sensor faulty. ▪ Check, replace.

Code	Component/designation	Error	Possible troubleshooting
E9003	Frost protection function error	Plate heat exchanger (PHE)	Measured value t_V1 < 0 °C ▪ Failure of the plate heat exchanger’s frost protection function due to low water flow. See error code E9004 / 7H. ▪ Failure of the plate heat exchanger’s frost protection function due to lack of refrigerant in the system. See error code E9015 / E4.
E9004	FLS flow meter	Flow error	Water flow is too low or completely absent. Minimum required flow: see Chap. 5 Check the following points: ▪ All shut-off valves in the water circuit must be fully open. ▪ Optional water filters must not be clogged. ▪ The heating system must operate within its operating range. ▪ The heating system and the unit’s internal circulator pump must be completely bled of air. ▪ Check on the controller whether the available water pressure is sufficient (> 0.5 bar). [→ Main menu → Info → Overview → Syst P] ▪ Check the operation of the 3-way diverter valve 3UVB1: compare the actual position of 3UVB1 to the displayed position [→ Main menu → Info → Overview → BPV]. ▪ Does this error occur during defrosting in space heating mode or DHW preparation? If an optional Backup-Heater is installed: check its power supply and fuses. ▪ Check the fuses (pump fuse (FU1) on board A1P and the circuit board fuse (F1) on the RoCon BM2C board). ▪ Check the FLS flow meter for clogging and proper operation, clean or replace it if necessary. ▪ Frost damage to the plate heat exchanger (outdoor unit)
E9005	Flow temperature sensor tv_, _BH	Flow temperature tv_, _BH > 75 °C	Backup-Heater flow temperature (tv_, _BH) too high. ▪ The flow temperature sensor is giving incorrect readings. Temperature sensor or connecting cable faulty. ▪ Check, replace. ▪ Contact issue A1P jumper on X3A.
E9006	Flow temperature sensor tv_, _BH	Flow temperature t_v, _BH > 65 °C
E9007	A1P circuit board	Board FI faulty	Communication fault between the outdoor heat pump and the indoor heat pump. ▪ Electromagnetic interference. ▪ Perform a reset. ▪ A1P board faulty. ▪ Replace the A1P board.
E9008	Temperature sensor (refrig- erant liquid side) t_L2	Refrigerant temperature outside valid range	No heat dissipation at the plate heat exchanger. ▪ Check the flow. ▪ If the flow is correct, replace the refrigerant temperature sensor.

Code	Component/designation	Error	Possible troubleshooting
E9009	Optional: Backup-Heater safety temperature limiter (EKBUxx)	Temperature limiter error	The thermal switch (temperature limiter) on the Backup-Heater (EKBUxx) has tripped. ▪ Check the position of the safety temperature limiter and reset it.
E9010	Jumper on A1P board	Temperature limiter error	The jumper on the “X21A” connector on the A1P board is missing. ▪ Plug in the jumper.
E9011	FLS flow meter	Flow meter error	FLS flow meter faulty. ▪ Replace the FLS flow meter.
E9012	Refrigerant temperature sensor	Refrigerant temperature sensor error	Measured value outside the permitted range. Sensor or connecting cable faulty. ▪ Check, replace.
E9013	Outdoor heat pump mainboard	Board FE faulty	▪ Outdoor heat pump mainboard faulty. ▪ Fan motor faulty. ▪ Check, replace.
E9014	High-pressure switch S1PH in the refrigerant system	High refrigerant pressure	The pressure in the refrigerant system is too high. ▪ High-pressure switch S1PH or fan motor faulty. ▪ Check, replace. ▪ Poor wiring contact. ▪ Flow too low in the heating system. ▪ Too much refrigerant charged. ▪ Check, replace. ▪ Service valves not opened on the outdoor heat pump. ▪ Open the service valves.
E9015	Pressure sensor S1NPH on the outdoor heat pump	Low refrigerant pressure	The pressure in the refrigerant system is too low. ▪ Refrigerant charge too low. ▪ Check, correct the cause, top up the refrigerant. ▪ Pressure sensor S1NPH on the outdoor heat pump faulty. ▪ Fin heat exchanger temperature sensor R4T faulty on the outdoor heat pump. ▪ The solenoid valve on the outdoor heat pump does not open. ▪ Outdoor heat pump mainboard faulty. ▪ Check, replace.

Code	Component/designation	Error	Possible troubleshooting
E9016	Electronic overload protection in the refrigerant compressor	Compressor overload protection	The refrigerant compressor’s overload protection has tripped. Pressure difference too great in the refrigerant circuit between the high-pressure and low-pressure sides (> 26 bar). ▪ Refrigerant compressor faulty. ▪ Inverter board faulty on the outdoor heat pump. ▪ Refrigerant compressor / inverter board wiring: poor contact. ▪ Too much refrigerant charged. ▪ Check, replace. ▪ Service valves not opened on the outdoor heat pump. ▪ Open the service valves.
E9017	Fan motor on the outdoor heat pump	Fan blocked	▪ A fan in the outdoor heat pump (RRLQ) is blocked. ▪ Check the fan for dirt or obstruction, clean and restore it to working condition if necessary. ▪ Fan motor faulty. ▪ Fan motor wiring: poor contact. ▪ Overvoltage at the fan motor. ▪ Fuse faulty in the outdoor heat pump. ▪ Inverter board faulty on the outdoor heat pump. ▪ Check, replace.
E9018	Expansion valve (electronic type)	Expansion valve	The electronic expansion valve in the outdoor heat pump is faulty, replace it.
E9019	Tank temperature sensor t_DHW2	DHW temperature > 85 °C	The tank temperature sensor t_DHW2 is giving a temperature reading > 85 °C. Sensor or connecting cable faulty. ▪ Check, replace.
E9020	Discharge temperature sensor (hot gas sensor) R2T on the outdoor heat pump’s refrigerant compressor too high	Compressor temperature high	▪ Discharge temperature sensor R2T on the refrigerant compressor or connecting cable faulty. ▪ Refrigerant compressor faulty. ▪ Check, replace.
E9021	High-pressure switch S1PH on the outdoor heat pump	System HPS	▪ High-pressure switch S1PH faulty. ▪ Outdoor heat pump mainboard faulty. ▪ Wiring, poor contact. ▪ Check, replace.

Code	Component/designation	Error	Possible troubleshooting
E9022	Outdoor temperature sensor R1T on the outdoor heat pump	Outdoor Sensor Error	Sensor or connecting cable faulty. ▪ Check, replace.
E9023	Tank temperature sensor t_DHW1 or _DHW2	DHW sensor error
E9024	Pressure sensor S1NPH on the outdoor heat pump	Pressure sensor
E9025	Discharge temperature sensor R2T on the outdoor heat pump	Return temperature sensor error
E9026	Suction temperature sensor R3T on the outdoor heat pump	Suction pipe sensor error
E9027	Fin heat exchanger temperature sensor R5T on the outdoor heat pump	Aircoil Defrost Sensor
E9028	Fin heat exchanger temperature sensor R4T on the outdoor heat pump (only for 11-16 kW units)	Aircoil Temp Sensor
E9029	Liquid-side temperature sensor R6T on the outdoor heat pump	Cooling FE sensor error

Code	Component/designation	Error	Possible troubleshooting
E9030	Temperature sensor R10T on the inverter board in the outdoor heat pump (only for 11-16 kW installations)	Electrical fault	Excess temperature in the outdoor heat pump. ▪ Outdoor temperature very high. ▪ Insufficient cooling of the inverter board. ▪ Air intake dirty/blocked. ▪ Faulty inverter board on the outdoor heat pump. ▪ Faulty temperature sensor on the inverter board, incorrect X111A connection. ▪ Check, remove the cause, replace. ▪ Contact the technician if necessary.
E9031	Voltage surges in electrical components		If this error occurs <15x, reliable operation of the indoor unit is still ensured. ▪ Sporadic message during the unit’s continuous self-monitoring. ▪ No further action required. If the error occurs 15x, it causes a lockout, which may be due to the following: ▪ Current mains overvoltage. ▪ Refrigerant compressor blocked or faulty. ▪ Faulty inverter board on the outdoor heat pump. ▪ Wiring, poor contact. ▪ Service valves not open on the outdoor heat pump. ▪ Check, remove the cause, replace. ▪ Contact the technician if necessary.
E9032	Electrical components		▪ Faulty refrigerant compressor. ▪ Faulty inverter board on the outdoor heat pump. ▪ Check, replace. ▪ Contact the technician if necessary.
E9033			▪ Refrigerant compressor blocked or faulty. ▪ Before the refrigerant compressor starts, temperature difference too high between the high-pressure side and the low-pressure side. ▪ Service valves not open on the outdoor heat pump. ▪ Check, remove the cause, replace. ▪ Contact the technician if necessary.
E9034			Communication error Internal communication interrupted on the outdoor heat pump. ▪ Electromagnetic interference. ▪ Perform a reset. ▪ Faulty mainboard on the outdoor heat pump. ▪ Faulty inverter board on the outdoor heat pump. ▪ Faulty fan motor. ▪ Wiring, poor contact. ▪ Check, remove the cause, replace. ▪ Contact the technician if necessary.

Code	Component/designation	Error	Possible troubleshooting
E9035	Inverter board on the outdoor heat pump	Faulty board FE	No mains power supply. ▪ Faulty inverter board on the outdoor heat pump. • Check, remove the cause, replace. • Contact the technician if necessary.
E9036	Temperature sensor R10T on the inverter board in the outdoor heat pump (only for 11-16 kW installations)	Electrical fault	Excess temperature in the outdoor heat pump ▪ Faulty inverter board on the outdoor heat pump. ▪ Faulty temperature sensor on the inverter board, incorrect X111A connection. • Check, remove the cause, replace. • Contact the technician if necessary.
E9037	Power setting	Incorrect power setting of the outdoor heat pump	▪ Contact a technician.
E9038	Sensors and parameters set on the outdoor heat pump	Refrigerant leak	Loss of refrigerant. ▪ Refrigerant quantity too low. See error code E9015 / E4. ▪ Blockage or leak in the refrigerant line. • Check, remove the cause, top up the refrigerant.
E9039		Under/Overvoltage	Mains voltage outside the permissible range 1 Sporadic error, shortly after a power outage. • No need to clear this error. 2 Faulty inverter board on the outdoor heat pump. • Check, replace. • Contact the technician if necessary.
E9041	Transmission error	Electrical components	Communication between the outdoor heat pump and the indoor heat pump is faulty. ▪ Wiring or connections, poor contact. ▪ No outdoor heat pump connected. ▪ Faulty A1P board. ▪ Faulty mainboard on the outdoor heat pump. • Check, replace.
E9042			Communication between the A1P board and RoCon BM2C is faulty. ▪ See error code E200.
E9043			Communication between the mainboard and the inverter board on the outdoor heat pump is faulty. ▪ Faulty mainboard on the outdoor heat pump. ▪ Faulty inverter board on the outdoor heat pump. ▪ Wiring, poor contact. • Check, remove the cause, replace.
E9044			The A1P board configuration does not match the outdoor heat pump ▪ Replace the A1P board. ▪ Contact the technician if necessary.

Code	Component/designation	Error	Possible troubleshooting
E9045	Software	DHW heating duration	DHW heating > 6 hours ▪ Check the heating element. ▪ Check that the power supply meets specifications. Check for frequency fluctuations. ▪ Check the fuses on the circuit boards. ▪ Check hot water consumption (it may be too high). ▪ Check the on-site hot water tap. ▪ Confirm that the software and the EEPROM on the hydraulic circuit board are working together correctly.
E9046	Software	Compressor startup	The system detects 16 times in 5 minutes that the current waveform is abnormal ▪ Check that the power supply meets specifications. Check for frequency fluctuations. ▪ Check the compressor. ▪ Check the compressor’s connection and wiring. ▪ Check the operation of the expansion valve (liquid backflow). ▪ Check the refrigerant charge amount and check for leaks. ▪ After resetting the power supply, check whether the error occurs when the compressor is not running: check the expansion valve.
E9047	Software	Overvoltage	The system detects 16 times in 5 min an overcurrent to the compressor > 20 A for > 2.5 seconds ▪ Check the compressor. ▪ Check the compressor’s connection and wiring. ▪ Check the operation of the expansion valve (liquid backflow). ▪ Check the refrigerant charge amount and check for leaks. ▪ Check the power transistor. ▪ Check the outdoor inverter circuit board. ▪ Check whether the current-flow LED blinks at regular intervals. ▪ Check whether the correct replacement part has been installed. ▪ Check whether the outdoor mainboard is receiving power. ▪ Check that the power supply meets specifications. Check for frequency fluctuations.

Code

Component/designation

Error

Possible troubleshooting

E9048

4-way valve

After 5 min of operation, the following condition occurs for 10 min:

Heating: condenser temperature minus outlet water temperature < -10 °C

▪ Check the outlet water thermistor on the heat exchanger.

▪ Check the thermistor on the refrigerant liquid side.

▪ Check whether the current-flow LED blinks at regular intervals.

▪ Check whether the correct replacement part has been installed.

▪ Check whether the outdoor mainboard is receiving power.

▪ Check the 4-way valve coil/wiring harness.

▪ Check the 4-way valve body.

▪ Check for a refrigerant shortage. Check for leaks.

▪ Check the refrigerant quality.

▪ Check the shut-off valves.

▪ Check the power supply to the hydraulic circuit board.

E9049

Temperature sensor on the evaporator

High-pressure cooling

The temperature measured by the temperature sensor on the fin heat exchanger exceeds 60 °C

▪ Check that the installation room meets specifications.

▪ Check the fan.

▪ Check the fan motor’s connection and wiring.

▪ Check the expansion valve.

▪ Check the outdoor inverter circuit board.

▪ Check whether the current-flow LED blinks at regular intervals.

▪ Check whether the correct replacement part has been installed.

▪ Check whether the outdoor mainboard is receiving power.

▪ Check the shut-off valves.

▪ Check the heat exchanger.

▪ Check the temperature sensor on the fin heat exchanger.

▪ Check the refrigerant quality.

Code	Component/designation	Error	Possible troubleshooting
E9050	Software	Voltage/current sensor	Fault detected in the power supply conditions, before or immediately after the compressor starts ▪ Check the compressor. ▪ Check the compressor’s connection and wiring. ▪ Check the operation of the expansion valve (liquid backflow). ▪ Check the refrigerant charge amount and check for leaks. ▪ Check the outdoor inverter circuit board. ▪ Check whether the current-flow LED blinks at regular intervals. ▪ Check whether the correct replacement part has been installed. ▪ Check whether the outdoor mainboard is receiving power.
E9052	Software	Compressor system	Compressor operating frequency below 55 Hz, voltage below 0.1 V, and input current below 0.5 A ▪ Check the compressor. ▪ Check the compressor’s connection and wiring. ▪ Check the operation of the expansion valve (liquid backflow). ▪ Check the refrigerant charge amount and check for leaks. ▪ Check that the power supply meets specifications. Check for frequency fluctuations. ▪ Check the outdoor inverter circuit board. ▪ Check whether the current-flow LED blinks at regular intervals. ▪ Check whether the correct replacement part has been installed.
E9053	Pressure sensor	Refrigerant pressure sensor	The pressure sensor detects an abnormal value for 3 minutes (> 4.5 MPa or < -0.05 MPa) ▪ Check the pressure sensor. ▪ Check whether the current-flow LED blinks at regular intervals. ▪ Check whether the correct replacement part has been installed. ▪ Check whether the outdoor mainboard is receiving power.
E9054	Pressure sensor	Refrigerant pressure sensor
E9055	Room temperature sensor (optional)	Temperature sensor error	Faulty sensor or connecting cable ▪ Check, replace
E9056	Outdoor temperature sensor (optional)	Temperature sensor error	Faulty sensor or connecting cable ▪ Check, replace
E9057		Overpressure in the refrigerant circuit; cutoff by the high-pressure switch	Please contact your service partner
E9058	Control unit on the outdoor unit	Temperature error	Please contact your service partner

Code	Component/designation	Error	Possible troubleshooting
E9059	Inverter on the outdoor unit	Temperature error	Please contact your service partner
E9060	Software	The screed program was not completed correctly	▪ Check the screed program ▪ Restart the program if necessary
W8006	DS pressure sensor	Pressure loss warning	Warning message: maximum permissible pressure loss exceeded. Not enough water in the heating system. ▪ Check the heating system for leaks, top up with water.
W8007	DS pressure sensor	The water pressure in the heating system is high	Warning: the water pressure has exceeded the maximum permissible value. ▪ Faulty diaphragm expansion tank or incorrectly set charge pressure. • Check, replace. ▪ [Max Pressure] parameter set too low. • Adjust the parameter if necessary. If the setting is correct, • drain water to reduce the system pressure.

Observe the maximum tightening torque of the temperature sensor (see Chap. 10.4).

8.4 Emergency operation

In the event of a heat pump failure, the Backup Heater or another heat source can serve as backup heating. If [Backup Mode] is set to “Yes,” backup mode is activated automatically in case of an error. Otherwise, backup mode can also be started only in case of an error, via the error screen (see the attached controller’s user manual). Only for 11-16 kW outdoor heat pumps.