Case Study

Case study: ‘first of its kind’ Bath Abbey

It’s not every day we see a case study at such a beautiful and challenging location. Bath Abbey was the subject of this impressive installation by isoenergy.

With this case study, the team really were put through their paces as they carried out the detailed design and installation of the ground source heat pump system that provides energy for the underfloor heating installed at the stunning Abbey.

The project is understood to be the first of its kind as it will source its energy for the ground source heat pump from the water that flows out of the Roman Baths in the centre of Bath.  


Property type: Community   

Technologies installed: Two heat pumps, ten energy blades  

Collector type: Energy blades   

Size (kW): 200kW   

New/retrofit: Retrofit   

Brand: Ecoforest  


Working in the Roman Drain’s humid and confined environment brought a new set of challenges for the isoenergy engineers. Work had to be carried out in short 20-minute sections to ensure the safety of workers underground. What’s more, the team were only able to transport the equipment down into the drain through a manhole inspection cover on York Street, and it all then had to be lowered the 7m to the floor of the Great Drain.  

Bath Abbey in all its splendour

The recommended solution:   

The thermal spring water was too corrosive to use directly in the underfloor heating system due to the high mineral content and particularly high levels of sulphates and chlorides. The plan was to raise the water level in a section of the drain using an internal weir. Corrosion-resistant custom-built EnergyBlade heat exchangers in the flow of the drain now extract the heat providing the source energy for the 200kW Ecoforest heat pumps that will provide energy for the new underfloor heating in the Abbey.  

Key features:   

Two Ecoforest heat pumps, ten energy blades   


1.1 million litres of hot water flow through the drain each day, which stays at a constant 40°C all year round. Energy is extracted from the hot water to produce enough energy to heat the historic Abbey as well as the adjacent row of Georgian cottages (Kingston Buildings) that house the Abbey offices, song school, and volunteer facilities.