Worcester Bosch
The Worcester Bosch Compress_5800i_AW is a monobloc air-source heat pump using R290 refrigerant, offering flow temperatures up to 75 degrees Celsius and a sound power level of 42 decibels.
The Worcester Bosch Compress_5800i_AW_Installation_Manual is a technical guide for the AW 4, 5, and 7 OR-S monobloc air-to-water inverter heat pumps. Using R290 refrigerant, these units achieve flow temperatures up to 75°C and a SCOP of 4.58 at 35°C. This reference covers installation clearances, hydraulic connections, and service steps for heating engineers and homeowners researching the 4.99 kW to 7.97 kW range.
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Full technical specifications extracted from the manufacturer brochure. Empty sections are hidden.
The Worcester Bosch Compress_5800i_AW series represents a shift toward natural refrigerants in the UK domestic market. Utilising R290 (propane), which has a Global Warming Potential (GWP) of just 3, these units are designed to meet future environmental regulations while providing high-grade heat. The range includes the AW 4, 5, and 7 OR-S models, with the 7 OR-S delivering a nominal capacity of 7.97 kW at A7/W35.
A primary technical advantage of this monobloc system is its ability to reach flow temperatures of 75°C. This high-temperature capability allows for easier integration into existing heating systems where traditional radiators may have been sized for gas boilers. The inverter-driven compressor ensures efficient modulation, resulting in a Seasonal Coefficient of Performance (SCOP) of 4.58 at 35°C and 3.52 at 55°C. Even at an outdoor temperature of -7°C, the 7 OR-S model maintains a capacity of 6.71 kW, ensuring reliable performance during peak winter conditions.
Acoustic performance is a critical factor for urban installations and Permitted Development rights. The outdoor unit features a sound power level of 42 dB(A), which can be further managed via a dedicated quiet mode. Physically, the outdoor unit measures 1100mm in width and 802mm in height, with a depth of 540mm. Engineers must account for the 143 kg unit weight during siting and ensure the mounting surface can support the load.
Installation requires specific clearances to maintain airflow and service access. A minimum of 400mm is required at the rear and sides, while the front must remain clear for 2000mm to prevent air recirculation. The hydraulic circuit uses 25mm pipe connections and is compatible with the 12 M, 12 E, and 12 MB control units.
Maintenance is streamlined through accessible components. Annual servicing includes cleaning the drip tray, which involves removing the left side cover and EPP insulation parts. Engineers must also perform a function check via the indoor unit and inspect power cables for mechanical damage. As the system uses A3-classified R290 refrigerant, installers must adhere to safety protocols regarding flammable gases, although the hermetically sealed monobloc design simplifies the process compared to split systems. The unit is Modbus compatible, allowing for integration into wider building management systems.
Common questions from engineers and homeowners about the Worcester Bosch 4 OR-S.
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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.