alpha innotec (ait-deutschland) · A niche brand in the UK. 99 codes across 1 product family, each taken from the manufacturer’s manuals. alpha innotec technical support ↗
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Type the code on your display or a word from its meaning. Each code opens its own page with what it means, whether it is safe and what you can check.
99 codes
| Code | Meaning | Stops? | Homeowner check? |
|---|---|---|---|
| 701 | Error low pressure. Please call AS: Low-pressure pressostat or low-pressure sensor in the refrigerant circuit has responded (air/water), or for longer than 20 s (brine/water). | Yes | Yes |
| 702 | Low pressure stop. Reset autom.: Air/water units only: low pressure in the refrigerant circuit has responded; heat pump restarts automatically after some time. | Yes | Yes |
| 703 | Antifreeze. Please call installer: Air/water units only: heat pump running and flow temperature < 5 °C - frost danger detected. | Yes | Yes |
| 704 | Error hot gas. Reset in hh:mm: Maximum hot-gas (discharge) temperature in the refrigerant circuit exceeded; automatic restart after the displayed time. | Yes | Yes |
| 705 | Motor protection VEN. Please call installer: Air/water units only: fan motor protection has responded. | Yes | Yes |
| 706 | Motor protection BCP. Please call installer: Brine/water or water/water units only: motor protection of the brine or well-water circulating pump or of the compressor has responded. | Yes | Yes |
| 707 | Coding of HP. Please call installer: Break or short circuit of the coding bridge (coding resistor) in the heat pump after first switch-on. | Yes | Yes |
| 708 | Return sensor. Please call installer: Break or short circuit in the return sensor. | Yes | Yes |
| 709 | Flow sensor. Please call installer: Break or short circuit in the flow sensor. No fault shutdown for brine/water or water/water units. | Partly | Yes |
| 710 | Hot gas sensor. Please call installer: Break or short circuit in the hot-gas sensor of the refrigerant circuit. | Yes | Yes |
| 711 | External temp. sensor. Please call installer: Break or short circuit in the outdoor (external) temperature sensor. No fault shutdown; value fixed to -5 °C. | No | Yes |
| 712 | Domestic hot water sensor. Please call installer: Break or short circuit in the domestic hot water sensor. No fault shutdown. | Partly | Yes |
| 713 | HS-on sensor. Please call installer: Break or short circuit in the heat source sensor (inlet). | Yes | Yes |
| 714 | Hot gas SW. Reset in hh:mm: Thermal application limit of the heat pump reached during DHW; domestic hot water off for hh:mm. Only triggers while compressor running. | Partly | Yes |
| 715 | High-pressure switch-off. Reset autom.: High pressure in the refrigerant circuit has responded; automatic restart after some time. | Yes | Yes |
| 716 | High-pressure fault. Please call installer: High-pressure pressostat in the refrigerant circuit has responded several times. | Yes | Yes |
| 717 | Flow HS. Please call installer: Water/water units: flow switch has responded during pre-rinsing time or operation. | Yes | Yes |
| 718 | Max. outside temp. Reset autom. in hh:mm: Air/water units only: outside temperature has exceeded permissible maximum; automatic restart after hh:mm. | Yes | Yes |
| 719 | Min. outside temp. Reset autom. in hh:mm: Air/water units only: outside temperature has fallen below permissible minimum; automatic restart after hh:mm. | Yes | Yes |
| 720 | HS temperature. Reset autom. in hh:mm: Brine/water or water/water units: temperature at evaporator outlet (heat source side) fell below the safety value several times; automatic restart after hh:mm. | Yes | Yes |
| 721 | Low-pressure switch-off. Reset autom.: Low-pressure pressostat or sensor in the refrigerant circuit has responded; automatic restart after some time (brine/water and water/water). | Yes | Yes |
| 722 | Tempdiff HW. Please call installer: Temperature spread in heating mode is negative (erroneous). | Yes | Yes |
| 723 | Tempdiff SW. Please call installer: Temperature spread in domestic hot water mode is negative (erroneous). | Yes | Yes |
| 724 | Tempdiff defrosting. Please call installer: Temperature spread in heating circuit > 15 K during defrosting (danger of frost). | Yes | Yes |
| 725 | System error DHW. Please call installer: Domestic hot water fault: desired tank temperature substantially undershot. | Partly | Yes |
| 726 | Sensor mixing circ 1. Please call installer: Break or short circuit in the mixing circuit 1 sensor. | Partly | Yes |
| 727 | Brine pressure. Please call installer: Brine pressure pressostat responded during pre-rinsing time or operation. | Yes | Yes |
| 728 | Sensor HS Off. Please call installer: Break or short circuit in the heat source sensor at the heat source outlet. | Yes | Yes |
| 729 | Rotating field error. Please call installer: Compressor without power after switching on (rotating field / phase sequence). | Yes | Yes |
| 730 | Screed heating error. Please call installer: Screed heating program could not reach a flow temperature level in the specified interval; program continues running. | No | Yes |
| 731 | Timeout TDI: Temperature required for thermal disinfection could not be reached within the set switching times. | No | Yes |
| 732 | Cooling fault. Please call installer: Heating water temperature of 16 °C undershot several times (cooling). | Partly | Yes |
| 733 | Anode fault. Please call installer: Fault input of the impressed-current anode has responded. | Partly | Yes |
| 734 | Anode fault. Please call installer: Error 733 present for more than two weeks; domestic hot water is locked. | Partly | Yes |
| 735 | Error Ext. En. Please call installer: Only with expansion board: break or short circuit in the 'External energy source' sensor. | Partly | Yes |
| 736 | Error solar collector. Please call installer: Only with expansion board: break or short circuit in the 'solar collector' sensor. | Partly | Yes |
| 737 | Error solar tank. Please call installer: Only with expansion board: break or short circuit in the 'solar tank' sensor. | Partly | Yes |
| 738 | Error mixing circle 2. Please call installer: Only with expansion board: break or short circuit in the 'mixing circle 2' sensor. | Partly | Yes |
| 739 | Error mixing circle 3. Please call installer: Only with expansion board: break or short circuit in the 'mixing circle 3' sensor. | Partly | Yes |
| 750 | Return sensor external. Please call installer: Break or short circuit in the external return sensor. | Yes | Yes |
| 751 | Phase monitoring fault: Phase-sequence relay has responded. | Yes | Yes |
| 752 | Flow error: Phase-sequence relay or flow switch has responded. | Yes | Yes |
| 755 | Lost connection to slave. Please call installer: A slave (parallel/cascade mode) has not responded for more than 5 minutes. | Partly | Yes |
| 756 | Lost connection to master. Please call installer: A master (parallel/cascade mode) has not responded for more than 5 minutes. | Partly | Yes |
| 757 | Low-pressure fault in W/W-appliance: Low-pressure pressostat in a water/water unit triggered repeatedly or for more than 20 s. After three occurrences the installation can only be cleared by authorised service personnel. | Yes | Yes |
| 758 | Defrosting malfunction: Five times in a row defrosting lasted longer than 10 minutes or ended with feed temperature < 10 °C. | Yes | Yes |
| 759 | TDI message: Thermal disinfection could not be carried out correctly 5 times in succession. | No | Yes |
| 760 | Defrosting fault: Defrosting ended 5 times in succession by maximum time (strong wind on evaporator). | Yes | Yes |
| 761 | LIN timeout: LIN connection interrupted. | Yes | Yes |
| 762 | Sensor compressor intake: Tü sensor error (compressor intake). | Yes | Yes |
| 763 | Sensor evaporator intake: Tü1 sensor error (evaporator intake). | Yes | Yes |
| 764 | Sensor compressor heater: Sensor error compressor heater. | Yes | Yes |
| 765 | Suction gas Overheating (SSH): Suction gas superheat outside limits (above/below 2 K) for longer than 5 minutes. Auto reset after 5 minutes or manual; repeated occurrences permanently block the refrigerant circuit. | Yes | Yes |
| 766 | compressor's functional range: Operation for 5 minutes outside the compressor's functional range; resets after max. 2 h. | Yes | Yes |
| 767 | STB E-Rod: Safety temperature limiter (STB) of the electric heating element has been activated. | Partly | Yes |
| 768 | Flow monitoring: Insufficient flow in defrost cycle. | Yes | Yes |
| 769 | Pump control: No valid flow signal from the circulating pump. Reset autom. | Yes | Yes |
| 770 | Low overheat: Superheat below limit value for a lengthy period. | Yes | Yes |
| 771 | High overheat: Superheat outside limit value for a lengthy period (manual text reads 'below'). | Yes | Yes |
| 775 | SEC EVI valve: Electronic expansion valve in the EVI circuit no longer recognised by the control. | Yes | Yes |
| 776 | limit of application-CP: Compressor operating outside its use limits for a lengthy period. | Yes | Yes |
| 777 | Expansion valve: Electronic expansion valve is defective. | Yes | Yes |
| 778 | Low pressure sensor: Low-pressure sensor is defective. | Yes | Yes |
| 779 | High pressure sensor: High-pressure sensor is defective. | Yes | Yes |
| 780 | EVI sensor: EVI sensor is defective. | Yes | Yes |
| 781 | Liquid temp. sensor before EXV: Liquid temperature sensor upstream of the expansion valve is defective. | Yes | Yes |
| 782 | Suction gas EVI temp. sensor: Suction gas EVI temperature sensor is defective. | Yes | Yes |
| 783 | Communication SEC board - Inverter: Connection between SEC board and inverter is disrupted. | Yes | Yes |
| 784 | VSS lockdown: Inverter is blocked. | Yes | Yes |
| 785 | SEC-Board defective: Error found in the SEC board. | Yes | Yes |
| 786 | Communication SEC board - Inverter: Connection between SEC board and HZ/IO is disrupted by the SEC board. | Yes | Yes |
| 787 | VD alert: Compressor signals faults. | Yes | Yes |
| 788 | Major VSS fault: Fault in the inverter. | Yes | Yes |
| 789 | LIN/Encoding not found: Control unit unable to find coding: LIN connection interrupted or coding resistor not detected. | Yes | Yes |
| 790 | Major VSS fault: Fault in the power supply of the inverter / compressor. | Yes | Yes |
| 791 | ModBus connection lost Inverter: No ModBus communication with inverter for at least 10 s or 10 packets lost. Reset autom. | Yes | Yes |
| 792 | LIN-connection lost: Unable to find a master board or any configuration. | Yes | Yes |
| 793 | Inverter Temperature: Temperature sensor fault in the inverter / internal inverter temperature too high at least 5x within 24 h. Fault acknowledges itself. | Yes | Yes |
| 794 | Overvoltage: Overvoltage on inverter. | Yes | Yes |
| 795 | Undervoltage: Undervoltage on inverter. | Yes | Yes |
| 796 | Safety switch off: Safety input triggered; manual reset required. Case 1 inverter malfunction; case 2 high-pressure pressostats triggered; case 3 (LWDV/Hybrox only) voltage fluctuations beyond standard. | Yes | Yes |
| 797 | MLRH is not supported: Heating rod regulating is not supported. | No | Yes |
| 798 | ModBus connection lost Fan: No ModBus communication with the fan for at least 10 s. Reset autom. | Yes | Yes |
| 799 | ModBus connection lost ASB: No ModBus communication with the ASB board for at least 10 s. Reset autom. | Yes | Yes |
| 800 | Desuperheater-error: Shutdown when desuperheater temperature >= 80 °C; released after 2 hours; if 5 times within 24 h error 800 is displayed. | Yes | Yes |
| 801 | HP offline: The heating and heat pump controller has no internet connection. | No | Yes |
| 802 | Temperature electrical switch box: Shutdown when switch-box temperature >= 80 °C; restarts below 70 °C. Reset autom. | Yes | Yes |
| 803 | Temperature electrical switch box Blockage: Error 802 tripped 3 times within 24 hours; manual reset required. | Yes | Yes |
| 804 | Sensor temperature electrical switch box: Sensor error: electrical switch box temperature. | Not stated | Yes |
| 805 | Sensor desuperheater: Sensor error: desuperheater temperature (or 'Enth' selected in FlexConfig - Out2 although not required). | Not stated | Yes |
| 806 | ModBus SEC: SEC board has no ModBus communication for at least 10 s or query failed 10 times in a row. Reset autom. | Yes | Yes |
| 807 | Lost ModBus communication: All ModBus communication faults with unit components present simultaneously for at least 10 s. Reset autom. | Yes | Yes |
| 808 | Hardware not supported: Controller software version incompatible with installed ASB hardware. | Not stated | Yes |
| 809 | Overheating hot gas (DSH): DSH_break triggered 3 times within 24 h. Reset autom. after 5 minutes or manually. | Yes | Yes |
| 810 | version parallel mode: Controllers connected in parallel operation have different software versions. | Partly | Yes |
| 811 | Check condensate pan. Please call installer: COPS float switch (condensate overflow protection) has tripped. | Yes | Yes |
| 812 | Maximum flow rate. Please call installer: Maximum permissible flow rate of the circulation pump exceeded 5 times within 24 h. | Not stated | Yes |
| 813 | Inverter not compatible. Please call installer: The heat pump inverter is not compatible; compressor blocked, only operation with ZWE (additional heater) possible. | Partly | Yes |
| 814 | Sensor defrosting. Please call installer: Defrosting sensor is defective. | Not stated | Yes |