To finance the pioneering scheme, Yarlington successfully bid for Government RHPP (Renewable Heat Premium Payment) funding, which was supplemented further via Kensaʼs partnership with Scottish and Southern Energy. To satisfy the funding conditions, Kensa were compelled to complete and commission all systems by mid December 2012, leaving a window of just three months for the drilling project to start and end.
The houses to benefit from the heat pumps were scattered in clusters across 10 Somerset villages over an area spanning 270 square miles.
The dwellings were each to be given their own Kensa GSHP of 3-6 kW, mounted on an individually cast concrete plinth, in a custom made weather-resistant enclosure affixed to the external wall. Each and every house was to have its own dedicated borehole, typically between 90m and 120m deep, drilled in the front garden.
The majority of the properties were post war semi detached or terraced single storey dwellings in tight knit, well established communities, all of them with sitting tenants, many of whom were older, more vulnerable residents.
The Yarlington & Kensa management teams were keen to get the job done efficiently and on time, however, their highest priority was the wellbeing of the communities. To this end, Synergy worked very closely with the management teams to ensure tenant liaison and expectation was co-ordinated. Furthermore, much care and consideration had to be exercised to protect and re-instate many of the tenants’ beloved gardens and shrubs. Often they were protected by hedges or fences. Therefore, given the requirement to generate as little mess and disruption on site as possible, mud drilling, though slower than air drilling, was the only realistic alternative.
Synergy committed three Comacchio rotary drills (405, 450P, 450P1), together with trailer mounted Mud Pumps and Tibban Mud Puppies for drilling mud cleansing. The Mud Puppies were invaluable in keeping the drilling site relatively free of drilling fluids and mud. Loops (from MGS) were installed with mechanised loop insertion units, also from MGS.
Due to the considered approach on this project, it can be seen that a significant amount of equipment needed to be accommodated and regularly repositioned on the quiet and narrow streets of the communities.
The geology was fairly straight forward (clay/mudstone) and the drilling of a (90m metre) borehole was usually accomplished within a working day.
To the residents of these sheltered communities, the drilling was a closely watched, talked about, and speculated upon event. The project called upon the considerable experience and diplomatic skills of the Synergy drillers. Together with the support of Kensa and the Yarlington Resident Liaison Officers, tenants were reassured of the process and kept informed of the schedule, which even when faced with the wettest conditions in hundreds of years, remained undeterred. The lesson most quickly learnt by Synergy was that however efficient the drilling operation may be, to ensure a successful operation the support of the locals was invaluable.
Adding to the complexity, inadequate mapping of underground services resulted in a delicate and time consuming operation.
The project also demanded a high level of documentation. Individual reports were filed for each property, operation and component, i.e. borehole depths, trench locations, loop and electrofusion fitting serial numbers were recorded for every installation, standardised pressure tests were also performed and documented.
Synergy were one of three drilling companies engaged for this project. The close proximity of the 10 villages and their mutual logistical issues and management ensured each drilling company got to know the other a little better and new friendships developed.
The Yarlington project was successfully completed, well within the deadline and on budget. Simon Lomax , MD of Kensa Engineering wrote:
“The need to co-fund with both DECC RH PP support and CERT grants meant the project fulfilment was compressed into three months. This demanded exceptional project management and cooperation with Yarlington Housing Group and our drillers, a task made simpler by the turnkey approach available as a manufacturer, and the professionalism demonstrated by all of our contractors.”
With new build projects contributing a small percentage of the buildings that will be in existence when the government's various, legally binding carbon reduction target deadlines are reached, the retrofitting of buildings is becoming increasingly important if these targets are to be attained. The area of retrofitting GSHPʼs to existing housing with limited space for collectors therefore has considerable potential.
On an individual level, Mr. & Mrs Coombe, Yarlington residents, summed it up best: “We were concerned with the upheaval and the new technology but after living with the system now over this cold spell we have heat and hot water when we want, the hot water temperature and pressure is lovely, and we have never run out, even after a long hot bubble bath.”