Baxi
The Baxi Assure HP55-11-3-PHMB is an 11 kW three-phase air source heat pump with an A+++ ErP rating at 35°C and a sound power level of 52 decibels.
The Baxi Assure HP55-11-3-PHMB is an 11 kW air source heat pump designed for domestic heating and hot water applications in the UK. Operating on a three-phase electrical supply, this unit provides high-efficiency performance with an ErP rating of A+++ at 35°C flow temperatures. Per the manufacturer's technical documentation, it is part of the Assure HP55 product family, offering a sound power level of 52 dB(LwA) for balanced external acoustic performance.
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Full technical specifications extracted from the manufacturer brochure. Empty sections are hidden.
The Baxi Assure HP55-11-3-PHMB represents an 11 kW nominal capacity solution within the Baxi Assure air source heat pump range. This specific model is a three-phase variant, making it suitable for larger domestic properties or light commercial settings where a balanced electrical load across phases is required. According to the available ErP energy label data, the unit achieves a seasonal space heating energy efficiency class of A+++ when operating at a 35°C flow temperature, and maintains an A++ rating at 55°C. These ratings indicate the unit is optimized for low-temperature heating systems, such as underfloor heating, while remaining capable of servicing traditional radiator circuits in retrofit scenarios.
In terms of acoustic performance, the manufacturer specifies a sound power level of 52 dB(LwA). For installers, this relatively low sound power level is a critical factor when conducting MCS-020 noise assessments to determine if the installation meets Permitted Development rights in the UK. The 11 kW output suggests the unit is capable of meeting the heat loss requirements of medium-to-large detached properties, though a full room-by-room heat loss calculation remains mandatory to ensure the heat pump is correctly sized for the building's specific thermal envelope.
As the technical data for this model is primarily extracted from ErP energy labels and marketing classifications, specific details regarding the refrigerant type, Global Warming Potential (GWP), and internal hydraulic components should be verified against the specific installation manual provided with the unit. The Assure HP55-11-3-PHMB is designed to integrate into the wider Baxi Assure ecosystem, which typically focuses on the social housing and new build sectors, emphasizing reliability and ease of maintenance for housing providers and contractors.
The electrical configuration requires a 3-phase supply, which distinguishes it from the standard single-phase domestic models. This allows for more stable operation and reduced startup current per phase compared to high-output single-phase units. Installers must ensure the property's electrical infrastructure is compatible with a three-phase heat pump installation and that the appropriate metering is in place.
While specific details on the compressor type or inverter technology are not explicitly detailed in the current extraction, the A+++ efficiency rating at 35°C implies the use of modern modulation technology to match the heat load of the building. This modulation helps prevent short-cycling, extending the lifespan of the compressor and maintaining consistent indoor comfort levels. For hot water production, the unit is typically paired with an unvented heat pump cylinder, sized to accommodate the 11 kW output for efficient reheat times and high flow rates at the taps.
Common questions from engineers and homeowners about the Baxi Assure HP55-11-3-PHMB.
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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.