Ariston
The Ariston NIMBUS PLUS M NET R32 is a split air-source heat pump system with capacities up to 15 kW, using R32 refrigerant and capable of 70°C flow temperature.
The Ariston NIMBUS PLUS M NET R32 is a split air-source heat pump system designed for domestic heating applications in the UK. This page provides technical specifications, fault codes, and maintenance guidelines for heating engineers. The system comprises an outdoor unit and an indoor unit, utilising R32 refrigerant for efficient operation. This reference details the various model variants and their respective outputs, aiding in installation, servicing, and troubleshooting.
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Full technical specifications extracted from the manufacturer brochure. Empty sections are hidden.
The Ariston NIMBUS PLUS M NET R32 is an inverter-type split air-source heat pump, offering a range of outdoor unit capacities from 3.5 kW to 15 kW. These units utilise R32 refrigerant, which has a Global Warming Potential (GWP) of 675 and a refrigerant charge of 2.1 kg, aligning with current environmental regulations. The system is capable of delivering a maximum flow temperature of 70°C and can operate effectively in outdoor temperatures as low as -35°C, ensuring performance across diverse UK weather conditions. Automatic defrost functionality is integrated to maintain efficiency during colder periods.
Physical dimensions for the outdoor unit are 1506mm in height, 1016mm in width, and 374mm in depth, with a weight of 131 kg. The indoor unit, such as the NIMBUS WH M R32, measures 716mm (H) x 600mm (W) x 358mm (D) and weighs 31 kg. Electrical requirements for the higher capacity M-T variants specify 400V, 50Hz, 3-phase power, with a maximum power consumption of 8.4 kW and requiring a 32A MCB rating. Hydraulic specifications include a maximum operating pressure of 3 bar and a minimum water flow rate of 7.17 litres per minute.
Control options for the NIMBUS PLUS M NET R32 include compatibility with SENSYS HD and Light Gateway controllers. The system supports weather compensation and is Smart Grid Ready, allowing for integration with smart energy management systems. OpenTherm compatibility is also featured. Users can manage the system via the Ariston NET app. For noise considerations, a quiet mode is available, enhancing suitability for residential installations. Annual service intervals are recommended, with detailed steps covering heat exchanger inspection, plumbing connections, water pressure checks, and electrical panel verification, ensuring long-term operational integrity.
Every fault code listed in the manufacturer brochure, with likely causes and engineer actions. Each code has a permalink — paste a URL like https://www.boilertag.com/heat-pumps/ariston/nimbus-150-m-ext-r32#fault-114 to jump straight to the entry.
| Code | Meaning | Details |
|---|---|---|
| 114 | Outside temperature not available Show causes & actionsEngineer action Temperature control activation based on the external sensor. External sensor not connected or damaged. Check the sensor's connection and replace it, if necessary. | Details |
| 730 | Buffer high probe error Show causes & actionsEngineer action Buffer filling inhibited. Check the hydraulic diagram. Buffer sensor not connected or damaged. Check the sensor's connection and replace it, if necessary. | Details |
| 731 | Buffer overtemperature Show causes & actionsEngineer action Buffer filling inhibited. Check the hydraulic diagram. Buffer sensor not connected or damaged. Check the sensor's connection and replace it, if necessary. | Details |
| 732 | Buffer low probe error Show causes & actionsEngineer action Buffer filling inhibited. Check the hydraulic diagram. Buffer sensor not connected or damaged. Check the sensor's connection and replace it, if necessary. | Details |
| 902 | System flow sensor damaged Show causes & actionsEngineer action Delivery sensor not connected or defective. Check the sensor's connection and replace it, if necessary. | Details |
| 923 | Heating circuit pressure error Show causes & actionsEngineer action Check for any water leakages in the hydraulic circuit. Faulty pressure switch. Defective cabling of the pressure switch. Check the connection of the pressure switch and replace it, if necessary. | Details |
| 924 | Communication error Show causes & actionsEngineer action Check the cabling between the TDM board and the Energy Manager. | Details |
| 927 | AUX inputs correspondence error Show causes & actionsEngineer action Verify the configuration of parameters 1.1.3 and 1.1.4. | Details |
| 928 | Energy supply shutdown configuration error Show causes & actionsEngineer action Check the configuration of parameter 1.1.5. | Details |
| 933 | Flow sensor overtemperature Show causes & actionsEngineer action Check the flow in the primary circuit. Delivery sensor not connected or defective. Check the sensor's connection and replace it, if necessary. | Details |
| 934 | DHW tank sensor damaged Show causes & actionsEngineer action Tank sensor not connected or defective. Check the sensor's connection and replace it, if necessary. | Details |
| 935 | Tank overtemperature Show causes & actionsEngineer action Check whether the 3-way valve is locked in the DHW position. Check the connection of the tank's sensor and replace it, if necessary. | Details |
| 936 | Floor thermostat 1 error Show causes & actionsEngineer action Check the flow of the under-floor system. Check the connection of the thermostat on the IN-AUX2 STE terminal of the Energy Manager and/or STT of the TDM. If the thermostat of the under-floor system is not present, apply an electrical jumper to terminal IN-AUX2 STE of the Energy Manager and/or STT of the TDM. | Details |
| 937 | No circulation error Show causes & actionsEngineer action Check that the main circuit has activated. | Details |
| 938 | Anode fault Show causes & actionsEngineer action Check the connection of the anode. Check whether there is any water in the indirect cylinder. Check the condition of the anode. Check the configuration of parameter 1.2.6. | Details |
| 940 | Hydraulic scheme not defined Show causes & actionsEngineer action Hydraulic diagram not selected through parameter 1.1.0. | Details |
| 955 | Water flow check error Show causes & actionsEngineer action Check the connection of the flow and return temperature sensors. | Details |
| 970 | Aux. pump configuration mismatch Show causes & actionsEngineer action Check the configuration of parameter 1.2.5. | Details |
| 2P2 | Thermal cleanse not complete Show causes & actionsEngineer action Sanitisation temperature not reached in 6 h: Check the drawing of domestic hot water during the thermal sanitisation cycle Check the activation of the heating element. | Details |
| 2P3 | DHW setpoint not reached in boost Show causes & actionsEngineer action Domestic hot water set-point temperature not reached during the boost cycle Check the drawing of domestic hot water during the DHW boost cycle Check the activation of the heating element. | Details |
| 2P4 | Electr. heater thermos. (manual) Show causes & actionsEngineer action Check the activation of the main circulation pump Check the flow with the reading of the flow meter through parameter 13.9.3 Check the condition of the safety thermostat and of the cabling. | Details |
| 2P5 | Electr. heater thermostat (auto) Show causes & actionsEngineer action Check the activation of the main circulation pump Check the flow with the reading of the flow meter through parameter 13.9.3 Check the condition of the safety thermostat and of the cabling. | Details |
| 2P7 | Precirculation error Show causes & actionsEngineer action Check the connection of the flow meter Run an automatic deaeration cycle 1.12.0. | Details |
| 2P8 | Low pressure warning Show causes & actionsEngineer action Check for any water leakages in the hydraulic circuit Faulty pressure switch Defective cabling of the pressure switch. Check the connection of the pressure switch and replace it, if necessary. | Details |
| 2P9 | SG ready input config. err. Show causes & actionsEngineer action Only one of the parameters 1.1.0 or 1.1.1 is set as an SG Ready input. | Details |
| 905 | HP compressor mismatch error Show causes & actionsReset procedure NO RESET Volatile | Details |
| 906 | HP fan mismatch error Show causes & actionsReset procedure NO RESET Volatile | Details |
| 907 | HP 4-way valve mismatch error Show causes & actionsReset procedure NO RESET Volatile | Details |
| 908 | Expansion valve mismatch error Show causes & actionsReset procedure NO RESET Volatile | Details |
| 909 | Fan off and heat pump on Show causes & actionsReset procedure NO RESET Volatile | Details |
| 910 | Inverter-TDM communication error Show causes & actionsReset procedure NO RESET Volatile | Details |
| 912 | 4-way valve error Show causes & actionsReset procedure Service reset | Details |
| 913 | LWT sensor error Show causes & actionsReset procedure NO RESET Volatile | Details |
| 914 | TR sensor error Show causes & actionsReset procedure NO RESET Volatile | Details |
| 917 | Freeze error Show causes & actionsReset procedure Service reset | Details |
| 918 | Pump down error Show causes & actionsReset procedure Service reset | Details |
| 922 | Freeze error Show causes & actionsReset procedure User reset | Details |
| 931 | Inverter error Show causes & actionsReset procedure User reset | Details |
| 947 | 4-way valve error Show causes & actionsReset procedure User reset | Details |
| 950 | Compressor delivery sensor error Show causes & actionsReset procedure Service reset | Details |
| 951 | TD sensor error Show causes & actionsReset procedure NO RESET Volatile | Details |
| 956 | HP compressor model mismatch Show causes & actionsReset procedure HP Power OFF | Details |
| 957 | HP fan model mismatch Show causes & actionsReset procedure HP Power OFF | Details |
| 960 | HP EWT sensor error Show causes & actionsReset procedure NO RESET Volatile | Details |
| 962 | Defrost energy Show causes & actionsReset procedure NO RESET Volatile | Details |
| 968 | ATGBUS TDM-EM communication error Show causes & actionsReset procedure NO RESET Volatile | Details |
| 994 | Low refrigerant charge error Show causes & actionsReset procedure HP Power OFF | Details |
| 997 | Compressor overcurrent Show causes & actionsReset procedure HP Power OFF | Details |
| 998 | Compressor overcurrent Show causes & actionsReset procedure NO RESET Volatile | Details |
| 9E5 | High-pressure pressure switch intervention Show causes & actionsReset procedure NO RESET Volatile | Details |
| 9E8 | Low-pressure pressure switch error with compressor OFF Show causes & actionsReset procedure NO RESET Volatile | Details |
| 9E9 | Klixon error with compressor OFF Show causes & actionsReset procedure NO RESET Volatile | Details |
| 9E18 | ST1 safety thermostat error Show causes & actionsReset procedure User reset | Details |
| 9E21 | Low refrigerant charge error Show causes & actionsReset procedure User reset | Details |
| 9E22 | Machine empty error Show causes & actionsReset procedure User reset | Details |
| 9E24 | EXV seized up error Show causes & actionsReset procedure Service reset | Details |
| 9E28 | High pressure protection Show causes & actionsReset procedure HP Power OFF | Details |
| 9E29 | High pressure protection Show causes & actionsReset procedure NO RESET Volatile | Details |
| 9E31 | Compressor thermostat protection Show causes & actionsReset procedure User reset | Details |
| 9E32 | Compressor thermostat protection Show causes & actionsReset procedure NO RESET Volatile | Details |
| 9E34 | Low-pressure protection Show causes & actionsReset procedure HP Power OFF | Details |
| 9E35 | Low-pressure protection Show causes & actionsReset procedure NO RESET Volatile | Details |
| 9E36 | Compressor phases current imbalance Show causes & actionsReset procedure HP Power OFF | Details |
| 9E37 | Compressor phases current imbalance Show causes & actionsReset procedure NO RESET Volatile | Details |
| 9E38 | Excessively steep compressor current variation Show causes & actionsReset procedure HP Power OFF | Details |
| 9E39 | Excessively steep compressor current variation Show causes & actionsReset procedure NO RESET Volatile | Details |
| 1 | Inverter output current sensor error | — |
| 2 | DC bus capacitors pre-charge error | — |
| 3 | Inverter input voltage sensor error | — |
| 4 | Inverter heat sink temperature sensor error | — |
| 5 | DSP&MCU communication error | — |
| 6 | Inverter input AC overcurrent | — |
| 7 | Inverter PFC current sensor error | — |
| 8 | Inverter PFC temperature sensor error | — |
| 9 | Corrupt EPROM | — |
| 10 | PFC HW overcurrent | — |
| 11 | PFC SW overcurrent | — |
| 12 | Inverter PFC overvoltage | — |
| 13 | A/D error | — |
| 14 | Addressing error | — |
| 15 | Compressor inverse rotation | — |
| 16 | No current variation on compressor phase | — |
| 17 | Misalignment between real and calculated speed | — |
| 18 | Vaux inverter error | — |
| 19 | Vstep Inverter/Control Board error | — |
| 20 | Inrush circuit error | — |
| 21 | PFC inverter error | — |
| 22 | DC bus overcurrent | — |
| 23 | Inverter module error | — |
| 24 | Compressor loss of synchronism | — |
| 25 | PCB overheating | — |
| 26 | HW interruption | — |
| 27 | Absence of configuration | — |
| 28 | SW error | — |
Patterns that group across the manufacturer's fault-code table. Each entry links to the full code listing further down the page.
Engineer: Temperature control activation based on the external sensor. External sensor not connected or damaged. Check the sensor's connection and replace it, if necessary.
Triggered by fault code 114.
Engineer: Buffer filling inhibited. Check the hydraulic diagram. Buffer sensor not connected or damaged. Check the sensor's connection and replace it, if necessary.
Triggered by fault code 730.
Engineer: Buffer filling inhibited. Check the hydraulic diagram. Buffer sensor not connected or damaged. Check the sensor's connection and replace it, if necessary.
Triggered by fault code 731.
Engineer: Buffer filling inhibited. Check the hydraulic diagram. Buffer sensor not connected or damaged. Check the sensor's connection and replace it, if necessary.
Common questions from engineers and homeowners about the Ariston NIMBUS 150 M EXT R32.
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Specifications on this page are extracted from the manufacturer brochure. Always cross-check against the latest datasheet before commissioning or quoting. Last updated 30 April 2026.
Triggered by fault code 732.
Engineer: Delivery sensor not connected or defective. Check the sensor's connection and replace it, if necessary.
Triggered by fault code 902.