Monitored Heat Pump Performance in a South London Edwardian Era Property

Helping YOU find good heating engineers. We share case studies from engineers in the Guild of Master Heat Engineers to help people find top installers, help gas and oil engineers increase their knowledge around heat pumps, and provide a solution for third-sector professionals to understand the industry better.

Overview

This case study highlights the transformation of an inefficient heating system within a period property in South East London. Michael Waring of Bromley Energy oversaw the installation and monitoring of a high performance heat pump system. By replacing ancient, fossil fuel technology with a precisely tailored renewable solution, the project demonstrates how low carbon heating thrives in older housing stock.

Master Heat Engineer

Key Specifications

• Technology: 7kW Vaillant aroTHERM plus (R290)

• Location: South East London (circa 1910 Edwardian Era Property)

• Hot Water Storage: Vaillant uniSTOR Slimline

• System Layout: Open-loop with 50l volumiser (No buffer tank)

• Design Flow Temperature: 45°C at -2°C Design Outdoor Temperature

• Primary Pipework: Primary Pro

• Measured Efficiency: 4.37 Overall system SCOP (4.48 Space Heating / 3.91 Hot Water

The Engineering Challenge:

The primary engineering challenge focused on moving away from high temperature fossil fuel combustion to a low temperature renewable system without disrupting the character of the home. Michael Waring conducted a rigorous, room by room heat loss calculation based on an outside design temperature of minus two degrees Celsius and an internal design temperature of twenty one degrees Celsius. Overcoming the legacy of a half century old distribution network required careful hydraulic planning to assure adequate flow rates.

System Design & Innovation

The innovative system design centres on a Vaillant aroTHERM plus seven kilowatt heat pump. Michael Waring optimised the design flow temperature to a low forty five degrees Celsius, relying on full weather compensation across a heat curve of 0.8. The plant room configuration incorporates a Vaillant uniSTOR Slimline 150 litre cylinder and a fifty litre volumiser. Notably, Michael Waring avoided the use of a buffer tank, choosing instead to optimise the existing distribution system to maintain direct, efficient flow. System control and remote data monitoring are managed via Vaillant sensoCOMFORT controls paired with an internet gateway.

Performance & Evidence

Data collected over the first year of operation provides clear evidence of exceptional system efficiency. The system delivered 8,282 kilowatt hours of space heating while consuming 1,847 kilowatt hours of electricity, resulting in a space heating SCOP of 4.48. For domestic hot water, the system delivered 1,762 kilowatt hours of heat and consumed 450 kilowatt hours of electricity, yielding a domestic hot water SCOP of 3.91. Combined, the total heat delivered reached 10,044 kilowatt hours against a total electricity consumption of 2,297 kilowatt hours, concluding in a highly impressive overall system SCOP of 4.37.

Furthermore, the heat pump accumulated 2,741 compressor run hours against 2,075 compressor starts. This reflects a remarkably low 0.76 starts per hour and an average run cycle length of seventy nine minutes, proving highly stable operation with negligible compressor cycling. The sole maintenance items identified during the first annual service were a faulty expansion vessel causing minor pressure loss and a noisy diverter valve, which was promptly replaced under warranty.

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Closing Thoughts

I’m now off to the Installer Show at the Birmingham NEC. Hope to see some of you there

Have a great week everyone.

Nathan

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