Vaillant
The Vaillant aroTHERM plus is a monobloc air-source heat pump using R290 refrigerant, offering flow temperatures up to 75°C and a COP of 4.8 at A7/W35 conditions.
The Vaillant aroTHERM plus is a monobloc air-source heat pump designed for domestic heating and hot water applications. Utilizing R290 natural refrigerant with a GWP of 3, it achieves flow temperatures up to 75°C, making it suitable for both new builds and retrofit projects. This guide provides technical specifications for the VWL 35/6, 55/6, and 75/6 variants, covering electrical requirements, hydraulic parameters, and the mandatory annual service schedule for UK heating engineers and system designers.
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Full technical specifications extracted from the manufacturer brochure. Empty sections are hidden.
The Vaillant aroTHERM plus represents a shift toward natural refrigerants in the UK heat pump market. By using R290 (propane), the unit achieves a Global Warming Potential (GWP) of just 3, significantly lower than synthetic alternatives. This monobloc system houses the entire refrigerant circuit within the outdoor unit, simplifying installation by requiring only hydraulic connections to the property.
Technical performance is centered on high flow temperatures and efficiency. The VWL 75/6 A variant delivers a nominal heat output of 4.6 kW at A7/W35 conditions with a Coefficient of Performance (COP) of 4.8. Even at lower ambient temperatures of -7°C, the unit maintains a capacity of 7 kW. A key differentiator is the maximum flow temperature of 75°C, which allows for effective legionella protection without relying solely on immersion heaters and enables the use of existing radiator circuits in some retrofit scenarios.
Physically, the VWL 75/6 outdoor unit measures 965mm in height, 1100mm in width, and 450mm in depth, with a net weight of 128 kg. Installers must ensure a minimum clearance of 500mm on the sides and 600mm at the front to facilitate airflow and maintenance access. Sound performance is a critical factor for planning; the unit has a sound power level of 53 dB(A), which can be reduced to 46 dB(A) when operating in quiet mode.
Electrically, the system operates on a 230V single-phase supply at 50Hz. The maximum power consumption is rated at 3.5 kW, with a startup current of 15A. Hydraulic requirements include a minimum operating pressure of 0.5 bar and a maximum of 3 bar, with a minimum water flow rate of 9 litres per minute.
Maintenance is mandatory every 12 months to ensure operational safety and efficiency. The service protocol includes eight primary steps, beginning with a check of the protective zone to ensure no ignition sources are present near the R290 circuit. Engineers must inspect the evaporator fins, fan rotation, and condensate discharge for blockages. A critical component of the annual check is the refrigerant circuit tightness test using a gas sniffer, alongside an inspection of electrical connections and earthing. For units older than three years, the damping feet must be checked for wear to prevent vibration issues.
Common questions from engineers and homeowners about the Vaillant VWL 55/6 A 230V S2.
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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.