What is the Vaillant aroTHERM VWL 55/3 A?

The Vaillant aroTHERM VWL 55/3 A is a 4.4 kW monobloc air-source heat pump with a 4.53 COP and a maximum flow temperature of 63°C. It is designed for domestic heating and hot water, using an inverter-driven compressor and R410A refrigerant to maintain efficiency across varying outdoor temperatures.

How do I register a Vaillant aroTHERM_VWL55_Installation_Instructions with BoilerTag?

Scan the QR code on the BoilerTag sticker after installation and confirm the model details, which will pre-fill from the catalogue. Record the installation date and your Gas Safe or MCS number to ensure every future service log is permanent and publicly viewable. The first 12 BoilerTag stickers are free for engineers. Order free BoilerTag stickers from the engineer dashboard.

What does fault code F.022 mean on the Vaillant aroTHERM?

Fault code F.022 indicates that the water pressure in the heating system is too low. This is typically caused by insufficient water volume or a leak in the circuit. Engineers should check for leaks, verify the pressure sensor functionality, and top up the system to between 1 and 2.5 bar.

What is the sound level of the Vaillant aroTHERM VWL 55/3 A?

The sound power level is 58 dB(A) under A7/W35 operating conditions. The unit also features a quiet mode, which can be configured to reduce noise emissions during specific time periods, assisting with compliance for local planning regulations and MCS-020 noise assessments.

What refrigerant does the Vaillant aroTHERM use?

The Vaillant aroTHERM VWL 55/3 A uses R410A refrigerant with a total charge of 1.8 kg. R410A has a Global Warming Potential (GWP) of 2088. Because this is a monobloc system, the refrigerant is hermetically sealed in the outdoor unit, simplifying the installation process.

What are the minimum installation clearances for the aroTHERM?

Minimum clearances are 1000mm at the front for airflow and service access, 250mm at the rear, and 120mm on both sides. Maintaining these distances is critical to prevent air recirculation, which can significantly reduce efficiency and lead to frequent defrost cycles in cold weather.

What causes fault code F.532 on the Vaillant aroTHERM?

Fault code F.532 signifies that the flow rate in the building circuit is too low. Common causes include air in the heating circuit, a blocked or missing dirt filter, or a faulty circulation pump. Engineers should purge the system and check the filter in the return pipe.

What is the maximum flow temperature for the aroTHERM VWL 55/3 A?

The maximum flow temperature is 63°C. This allows the unit to be used for both space heating and domestic hot water production, though efficiency is highest when operating at lower flow temperatures, such as 35°C for underfloor heating systems.

Is the Vaillant aroTHERM compatible with weather compensation?

Yes, the aroTHERM is fully compatible with weather compensation when used with the VRC 700 system control. This allows the heat pump to adjust its flow temperature based on the outdoor ambient temperature, maximizing the COP and reducing overall energy consumption.

What electrical supply is required for the aroTHERM VWL 55/3 A?

The unit requires a single-phase 230V, 50Hz power supply. It has a startup current of 13A and requires a 16A MCB. All electrical connections should be checked annually to ensure they are secure and that the earthing is functional.

What does fault code F.022 mean on the Vaillant VWL 85/3 A 230 V?

Water pressure too low Likely causes: Insufficient water in the heating system. Check for leaks and top up the heating system.

What does fault code F.037 mean on the Vaillant VWL 85/3 A 230 V?

Fan fault Likely causes: Obstruction in the product's air pipe; Fan motor not connected or defective; The connection between the main PCB and the fan PCB is damaged or broken. Check for obstructions and verify fan connections.

What does fault code F.042 mean on the Vaillant VWL 85/3 A 230 V?

Fault: Coding resistor Likely causes: The product's coding resistor is missing or is defective; Coding resistor value outside the permissible range; X25 plug not connected or was connected incorrectly. Check coding resistor and X25 plug connection.

What does fault code F.073 mean on the Vaillant VWL 85/3 A 230 V?

Fault: Water pressure sensor Likely causes: Line to water pressure sensor is broken or has a short circuit. Check sensor wiring and sensor functionality.

What does fault code F.086 mean on the Vaillant VWL 85/3 A 230 V?

Surface-mounted thermostat opened Likely causes: Underfloor heating temperature too high; Heating circuit flow rate quantity too low; Underfloor heating circuit is closed. Check flow rates and temperature settings.

What does fault code F.103 mean on the Vaillant VWL 85/3 A 230 V?

Fault: Spare part detection Likely causes: The parameter Max. duration power supply cut-off has been poorly set; The main PCB that is fitted as a spare part or the frequency converter does not match the product. Verify PCB compatibility and check settings.

What does fault code F.514 mean on the Vaillant VWL 85/3 A 230 V?

Temp. sensor fault: Compressor inlet Likely causes: Sensor is defective; Incorrectly connected to the main PCB. Check sensor and wiring.

What does fault code F.517 mean on the Vaillant VWL 85/3 A 230 V?

Temp. sensor fault: Compressor outlet Likely causes: Sensor is defective; Incorrectly connected to the main PCB. Check sensor and wiring.

What does fault code F.519 mean on the Vaillant VWL 85/3 A 230 V?

Sensor fault: Return temperature Likely causes: Sensor is defective; Incorrectly connected to the main PCB. Check sensor and wiring.

What does fault code F.520 mean on the Vaillant VWL 85/3 A 230 V?

Sensor fault: Flow temperature Likely causes: Sensor is defective; Incorrectly connected to the main PCB. Check sensor and wiring.

What does fault code F.523 mean on the Vaillant VWL 85/3 A 230 V?

Sensor fault: VF1 Likely causes: Line to temperature sensor VF1 is broken or has a short circuit. Check wiring to VF1 sensor.

What does fault code F.526 mean on the Vaillant VWL 85/3 A 230 V?

Sensor fault: Temp. environment circuit EEV Likely causes: Sensor is defective; Incorrectly connected to the main PCB. Check sensor on the evaporator.

What does fault code F.532 mean on the Vaillant VWL 85/3 A 230 V?

Building circuit: Flow rate too low Likely causes: Heating circuit not fully purged; Dirt filter in the heating circuit return is missing or blocked; Water deficiency; Pressure loss in the heating circuit too high; Pump cabling defective; Pump faulty. Check flow rate quantity during sensor/actuator…

What does fault code F.536 mean on the Vaillant VWL 85/3 A 230 V?

Compressor outlet temp. too high Likely causes: Refrigerant quantity too low; Sensor is defective or incorrectly connected; Premature expansion in the liquid area; Electronic expansion valve defective; Heat exchanger blocked. Check refrigerant charge and sensor accuracy.

What does fault code F.537 mean on the Vaillant VWL 85/3 A 230 V?

High-pressure switch opened Likely causes: Refrigerant volume too high or too low; Vacuum insufficient; Incondensable particle in the refrigerant circuit; Pressure switch or electrical connection defective; Flow rate quantity too high; Insufficient heat transfer in the heat exchanger. Check refrige…

What does fault code F.539 mean on the Vaillant VWL 85/3 A 230 V?

Refrigerant pressure too low Likely causes: Refrigerant quantity too low; Air flow too low; No thawing; Resistance heating in condensate receiver defective; 4-port diverter valve defective; Electronic expansion valve motor defective. Check for leaks and verify fan/defrost operation.

What does fault code F.546 mean on the Vaillant VWL 85/3 A 230 V?

Sensor fault: High pressure Likely causes: Cabling defective. Check wiring to high pressure sensor.

What does fault code F.554 mean on the Vaillant VWL 85/3 A 230 V?

Refrigerant pressure not in operating range Likely causes: Refrigerant volume too high or too low; Incondensable particle in the refrigerant circuit; Electronic expansion valve defective; Insufficient heat exchange; 4-port diverter valve defective; Temperature sensor defective. Check refrigerant ci…

What does fault code F.582 mean on the Vaillant VWL 85/3 A 230 V?

EEV fault Likely causes: Cable insulation defective; Connection broken. Check EEV wiring and connections.

What does fault code F.585 mean on the Vaillant VWL 85/3 A 230 V?

Sensor fault: Temp. building circuit EEV Likely causes: Sensor is defective; Incorrectly connected to the main PCB. Check sensor on the condenser.

Vaillant aroTHERM VWL 55/3 A — Specs & Fault Codes

Engineer's overview

The Vaillant aroTHERM monobloc range, specifically the VWL 55/3 A and VWL 85/3 A models, represents a versatile air-to-water heating solution for UK properties. The VWL 55/3 A variant delivers a nominal heat output of 4.4 kW at A7/W35 conditions with a Coefficient of Performance (COP) of 4.53. For higher demand scenarios, the VWL 85/3 A provides 7.07 kW. Both units utilize R410A refrigerant with a 1.8 kg charge, housed entirely within the outdoor casing to simplify installation by removing the need for F-gas qualifications for the hydraulic connection.

Physical installation requires careful site selection to ensure performance and longevity. The outdoor unit measures 834mm in height, 970mm in width, and 408mm in depth, weighing 90 kg. Engineers must maintain a minimum clearance of 1000mm at the front for airflow and maintenance access, with at least 250mm behind the unit and 120mm at the sides. These clearances are vital for the reverse cycle defrost method to function effectively, particularly when ambient temperatures approach the unit's lower operating limit of -20°C.

Hydraulic integration is managed via 1-inch (31.75mm) pipework, supporting a maximum operating pressure of 3 bar. The VWL 55/3 A requires a minimum water flow rate of 6.33 litres per minute. For control, the system is compatible with the VRC 700 system control and the VWZ AI heat pump control interface module, enabling weather compensation to optimize efficiency. The unit features a sound power level of 58 dB(A) at A7/W35, and a quiet mode is available to further reduce noise emissions during sensitive hours.

Electrical requirements for these single-phase 230V units include a 16A MCB rating, with a startup current of 13A. Maintenance should be performed every 12 months, focusing on the cleanliness of the ribbed pipe heat exchanger and the integrity of the refrigerant circuit. Common diagnostic issues include F.022 for low water pressure and F.532 for insufficient flow rates in the building circuit. Engineers should also monitor F.751, which indicates compressor overcurrent, often caused by dirty heat exchangers or power supply fluctuations. Proper registration of the unit is required to validate the manufacturer's warranty terms.

VWL 85/3 A 230 V fault codes

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/vaillant/vwl-85-3-a-230-v#fault-f.022 to jump straight to the entry.

Complete list of fault codes for this Vaillant VWL 85/3 A 230 V
Code	Meaning	Details
F.022	Water pressure too low Show causes & actions Insufficient water in the heating system Likely causes Insufficient water in the heating system Engineer action Check for leaks and top up the heating system.	Details
F.037	Fan fault Show causes & actions Obstruction or electrical failure of the fan Likely causes Obstruction in the product's air pipe Fan motor not connected or defective The connection between the main PCB and the fan PCB is damaged or broken Engineer action Check for obstructions and verify fan connections.	Details
F.042	Fault: Coding resistor Show causes & actions Coding resistor missing or out of range Likely causes The product's coding resistor is missing or is defective Coding resistor value outside the permissible range X25 plug not connected or was connected incorrectly Engineer action Check coding resistor and X25 plug connection.	Details
F.073	Fault: Water pressure sensor Show causes & actions Line to water pressure sensor is broken or has a short circuit Likely causes Line to water pressure sensor is broken or has a short circuit Engineer action Check sensor wiring and sensor functionality.	Details
F.086	Surface-mounted thermostat opened Show causes & actions Safety thermostat has triggered Likely causes Underfloor heating temperature too high Heating circuit flow rate quantity too low Underfloor heating circuit is closed Engineer action Check flow rates and temperature settings.	Details
F.103	Fault: Spare part detection Show causes & actions Incorrect spare part or parameter setting Likely causes The parameter Max. duration power supply cut-off has been poorly set The main PCB that is fitted as a spare part or the frequency converter does not match the product Engineer action Verify PCB compatibility and check settings.	Details
F.514	Temp. sensor fault: Compressor inlet Show causes & actions Sensor is defective or incorrectly connected to the main PCB Likely causes Sensor is defective Incorrectly connected to the main PCB Engineer action Check sensor and wiring.	Details
F.517	Temp. sensor fault: Compressor outlet Show causes & actions Sensor is defective or incorrectly connected to the main PCB Likely causes Sensor is defective Incorrectly connected to the main PCB Engineer action Check sensor and wiring.	Details
F.519	Sensor fault: Return temperature Show causes & actions Sensor is defective or incorrectly connected to the main PCB Likely causes Sensor is defective Incorrectly connected to the main PCB Engineer action Check sensor and wiring.	Details
F.520	Sensor fault: Flow temperature Show causes & actions Sensor is defective or incorrectly connected to the main PCB Likely causes Sensor is defective Incorrectly connected to the main PCB Engineer action Check sensor and wiring.	Details
F.523	Sensor fault: VF1 Show causes & actions Line to temperature sensor VF1 is broken or has a short circuit Likely causes Line to temperature sensor VF1 is broken or has a short circuit Engineer action Check wiring to VF1 sensor.	Details
F.526	Sensor fault: Temp. environment circuit EEV Show causes & actions Sensor is defective or incorrectly connected to the main PCB Likely causes Sensor is defective Incorrectly connected to the main PCB Engineer action Check sensor on the evaporator.	Details
F.532	Building circuit: Flow rate too low Show causes & actions Flow rate in the heating circuit is below minimum requirements Likely causes Heating circuit not fully purged Dirt filter in the heating circuit return is missing or blocked Water deficiency Pressure loss in the heating circuit too high Pump cabling defective Pump faulty Engineer action Check flow rate quantity during sensor/actuator test. Purge circuit and check filter.	Details
F.536	Compressor outlet temp. too high Show causes & actions Refrigerant temperature at compressor outlet exceeds limits Likely causes Refrigerant quantity too low Sensor is defective or incorrectly connected Premature expansion in the liquid area Electronic expansion valve defective Heat exchanger blocked Engineer action Check refrigerant charge and sensor accuracy.	Details
F.537	High-pressure switch opened Show causes & actions Refrigerant circuit high pressure limit reached Likely causes Refrigerant volume too high or too low Vacuum insufficient Incondensable particle in the refrigerant circuit Pressure switch or electrical connection defective Flow rate quantity too high Insufficient heat transfer in the heat exchanger Engineer action Check refrigerant levels and heat exchanger cleanliness.	Details
F.539	Refrigerant pressure too low Show causes & actions Refrigerant circuit low pressure limit reached Likely causes Refrigerant quantity too low Air flow too low No thawing Resistance heating in condensate receiver defective 4-port diverter valve defective Electronic expansion valve motor defective Engineer action Check for leaks and verify fan/defrost operation.	Details
F.546	Sensor fault: High pressure Show causes & actions Cabling defective Likely causes Cabling defective Engineer action Check wiring to high pressure sensor.	Details
F.554	Refrigerant pressure not in operating range Show causes & actions Pressure levels outside normal parameters Likely causes Refrigerant volume too high or too low Incondensable particle in the refrigerant circuit Electronic expansion valve defective Insufficient heat exchange 4-port diverter valve defective Temperature sensor defective Engineer action Check refrigerant circuit components and charge.	Details
F.582	EEV fault Show causes & actions Electronic expansion valve electrical fault Likely causes Cable insulation defective Connection broken Engineer action Check EEV wiring and connections.	Details
F.585	Sensor fault: Temp. building circuit EEV Show causes & actions Sensor is defective or incorrectly connected to the main PCB Likely causes Sensor is defective Incorrectly connected to the main PCB Engineer action Check sensor on the condenser.	Details
F.685	Communication fault: eBUS Show causes & actions eBUS communication failure Likely causes The product is not connected to the control Polarity inverted Engineer action Check eBUS wiring and polarity.	Details
F.750	Connection fault: Compressor Show causes & actions Compressor electrical connection fault Likely causes Cable insulation defective Connection broken Engineer action Check compressor wiring.	Details
F.751	Compressor: Overcurrent fault Show causes & actions Compressor drawing too much current Likely causes The product's power supply is too low The fin-type heat exchanger or heat exchanger is dirty Engineer action Check power supply and clean heat exchangers.	Details
F.752	Fault: Frequency converter Show causes & actions Inverter box or power supply fault Likely causes The parameter Max. duration power supply cut-off has been poorly set Inverter box damaged The cooler inverter box is blocked Faulty power supply Engineer action Check inverter box and power supply.	Details
F.753	Connection fault: Frequency converter not recognised Show causes & actions Communication failure between main PCB and inverter Likely causes The parameter Max. duration power supply cut-off has been incorrectly set The connection between the main PCB and the inverter box is damaged or broken Inverter box is not switched on Engineer action Check wiring between main PCB and inverter.	Details
F.754	Fault: Fan unit Show causes & actions Fan PCB or connection fault Likely causes The connection between the main PCB and the fan PCB is damaged or broken The fan PCB is defective Engineer action Check fan PCB and wiring.	Details
F.755	Fault: 4-port diverter valve position incorrect Show causes & actions Mechanical or electrical problem with the 4-port valve Likely causes Mechanical or electrical problem Coil voltage incorrect Cable harness fault Engineer action Check valve movement and coil voltage. Check sensor for finned-tube heat exchanger.	Details
F.774	Sensor fault: Air inlet temperature Show causes & actions The temperature sensor is defective or incorrectly connected to the main PCB Likely causes Sensor is defective Incorrectly connected to the main PCB Engineer action Check air inlet temperature sensor.	Details
F.1288	Fault: SP1 cylinder temperature sensor Show causes & actions Sensor is defective or has not been correctly connected to the VWZ AI module Likely causes Sensor is defective Incorrectly connected to the VWZ AI heat pump control interface module Engineer action Check cylinder sensor and VWZ AI module connection.	Details

Common VWL 85/3 A 230 V problems & troubleshooting

Patterns that group across the manufacturer's fault-code table. Each entry links to the full code listing further down the page.

How to fix the VWL 85/3 A 230 V water pressure too low

Engineer: Check for leaks and top up the heating system.

Triggered by fault code F.022.

How to fix the VWL 85/3 A 230 V fan fault

Engineer: Check for obstructions and verify fan connections.

Triggered by fault code F.037.

How to fix the VWL 85/3 A 230 V fault: coding resistor

Engineer: Check coding resistor and X25 plug connection.

Triggered by fault code F.042.

How to fix the VWL 85/3 A 230 V fault: water pressure sensor

Engineer: Check sensor wiring and sensor functionality.

Triggered by fault code F.073.

VWL 85/3 A 230 V

VWL 85/3 A 230 V at a glance

Register this Vaillant VWL 85/3 A 230 V on BoilerTag

VWL 85/3 A 230 V data sheet

Engineer's overview

VWL 85/3 A 230 V fault codes

Common VWL 85/3 A 230 V problems & troubleshooting

How to fix the VWL 85/3 A 230 V water pressure too low

How to fix the VWL 85/3 A 230 V fan fault

How to fix the VWL 85/3 A 230 V fault: coding resistor

How to fix the VWL 85/3 A 230 V fault: water pressure sensor

How to fix the VWL 85/3 A 230 V surface-mounted thermostat opened

VWL 85/3 A 230 V FAQs

Every boiler brochure, free with BoilerTag

Working on a Vaillant VWL 85/3 A 230 V?

Likely causes that trigger multiple VWL 85/3 A 230 V fault codes

VWL 85/3 A 230 V at a glance

Register this Vaillant VWL 85/3 A 230 V on BoilerTag

VWL 85/3 A 230 V data sheet

Engineer's overview

VWL 85/3 A 230 V fault codes

Common VWL 85/3 A 230 V problems & troubleshooting

How to fix the VWL 85/3 A 230 V water pressure too low

How to fix the VWL 85/3 A 230 V fan fault

How to fix the VWL 85/3 A 230 V fault: coding resistor

How to fix the VWL 85/3 A 230 V fault: water pressure sensor

How to fix the VWL 85/3 A 230 V surface-mounted thermostat opened

VWL 85/3 A 230 V FAQs

What is the sound level of the Vaillant aroTHERM VWL 55/3 A?

What refrigerant does the Vaillant aroTHERM use?

What are the minimum installation clearances for the aroTHERM?

What causes fault code F.532 on the Vaillant aroTHERM?

What is the maximum flow temperature for the aroTHERM VWL 55/3 A?

Is the Vaillant aroTHERM compatible with weather compensation?

What electrical supply is required for the aroTHERM VWL 55/3 A?

Every boiler brochure, free with BoilerTag

Other Vaillant heat pumps

Working on a Vaillant VWL 85/3 A 230 V?

Likely causes that trigger multiple VWL 85/3 A 230 V fault codes