Baxi
The Baxi HP60 and Assure HP55 are 6.26 kW monobloc air source heat pumps using R290 refrigerant, offering a 75°C maximum flow temperature and a SCOP of 5.22 at 35°C.
The Baxi HP60-6-1-PHMB and Assure HP55-6-1-PHMB are high-temperature monobloc air source heat pumps designed for domestic heating and hot water. Utilizing R290 refrigerant with a low Global Warming Potential of 3, these units deliver a nominal output of 6.26 kW at A7/W35. With a maximum flow temperature of 75°C and A+++ ErP ratings across both 35°C and 55°C applications, they provide a versatile solution for both new builds and retrofit heating system upgrades.
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The Baxi HP60-6-1-PHMB and Assure HP55-6-1-PHMB represent a shift toward natural refrigerants in the UK domestic market. Both models utilize R290 (propane), which offers a significantly lower Global Warming Potential (GWP) of 3 compared to traditional synthetic refrigerants. This monobloc system houses all refrigeration components within the outdoor unit, simplifying installation by requiring only hydraulic connections to the property.
Performance is characterized by high efficiency and high-temperature capability. At a flow temperature of 35°C, the unit achieves a Seasonal Coefficient of Performance (SCOP) of 5.22, while at 55°C, it maintains a SCOP of 3.9. These figures contribute to an ErP rating of A+++ for both low and medium-temperature operations. The ability to reach a maximum flow temperature of 75°C is particularly relevant for retrofit scenarios where existing radiator sizing might otherwise necessitate extensive upgrades, although system design should always prioritize the lowest possible flow temperature for maximum efficiency.
The physical footprint of the outdoor unit is 1301mm in width, 725mm in height, and 426mm in depth, with a net weight of 94kg. Installation requires specific clearances to ensure adequate airflow and service access: 300mm behind the unit, 500mm at the sides, and 1000mm at the front. The unit operates on a single-phase 230V supply and requires a 16A MCB.
Acoustic performance is a critical factor for urban installations and Permitted Development rights. The HP60 and Assure HP55 models feature a sound power level (LwA) of 48 dB(A) and a sound pressure level of 40 dB(A) at one meter. A quiet mode is available to further reduce noise emissions during sensitive periods.
Hydraulically, the system is designed for a maximum operating pressure of 3 bar. It is compatible with the Baxi ASHP Pre-plumbed Cylinder or standard ASHP cylinders, and control is managed via the Baxi START App. For long-term reliability, Baxi offers an extended warranty of up to 7 years, provided the installation is performed by a qualified engineer and registered according to manufacturer terms. The unit is capable of operating in outdoor temperatures as low as -25°C, ensuring heating continuity during extreme UK winter conditions.
Common questions from engineers and homeowners about the Baxi HP60-6-1-PHMB and Assure HP55-6-1-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.