Client: Exeter Diocese
Location: Exeter
System: Ariston Nimbus Pocket 12 kW Air Source Heat Pump
Cylinder: 250L unvented solar-ready unit
Status: Commissioned and certificated by 2nd April (BUS grant deadline)
Exeter Air Source Heat Pump Installation Overview
Working on behalf of the Exeter Diocese, Synergi SW was tasked with replacing an ageing oil-fired heating system at a vicarage located within Dartmoor National Park. The property required a full transition to renewable energy, delivering both heating and hot water via an Ariston Nimbus Pocket 12 kW air source heat pump.
The project presented several logistical and planning challenges, as the home sits within a Conservation Area with limited exterior space. Careful consideration was given to equipment placement to meet both planning constraints and the practical needs of the occupants, a family with four young children.
Design and Installation
After carrying out a full heat loss survey, our design team identified the left-hand side of the property as the most suitable location for the outdoor unit. A custom ground base with integrated condensate drainage was installed, with the primary pipework neatly routed up the external wall, through the gable, and into the loft space. From there, pipework continued to the existing cylinder cupboard and down to the utility room where the new plant equipment was installed.
A 250L unvented solar-ready cylinder was fitted in the utility room alongside the buffer tank, ancillary equipment, and wiring. To optimise efficiency and ensure comfort, the system was fitted with weather compensation controls and a priority hot water open-loop schematic. Magnetic and debris filters, as well as anti-freeze valves, were installed to protect the system without using environmentally harmful chemicals.
Internally, several radiators were upgraded to suit the lower flow temperatures of the heat pump. Others were retained or repurposed in different rooms, and new 28mm heating pipework was run along the landing to improve heat distribution throughout the property.
Performance and Efficiency
The new system operates at a design flow temperature of 45°C and achieves an MCS Seasonal Coefficient of Performance (SCOP) of 4.22. The property’s heating demand, previously met by oil, is now delivered through renewable electricity. Annual electricity consumption for the heat pump is estimated at around 7,000 kWh, replacing an oil consumption equivalent of nearly 29,000 kWh, marking a substantial improvement in energy efficiency and carbon reduction.
Customer Experience and Aftercare
Given the household’s needs, works were carefully scheduled to minimise disruption, with engineers working between 8:00am and 4:30pm and maintaining clear communication throughout. Hot water and heating were restored daily where possible, ensuring minimal inconvenience. Any final adjustments or minor finishing works were completed in the following week.
Upon completion, the system was fully commissioned and MCS-certified ahead of the grant deadline. The client received all user manuals, warranty documents, and maintenance guidance, ensuring long-term peace of mind.
Exeter Air Source Heat Pump Installation Outcome
This installation successfully replaced an old oil boiler with a low-carbon, high-efficiency heating system while meeting conservation and planning requirements. The project demonstrates how thoughtful design, technical expertise, and clear communication can deliver a renewable solution even in complex, heritage-sensitive settings.
The result is a modern, reliable, and efficient heating system that supports the Diocese’s ongoing sustainability goals while providing year-round comfort for the residents.
