This section provides details of an example project featuring a cascaded ground source heat pump system fed by a slinky ground array.

We have provided a ground source heat pump design with schematic drawings, ground source heat pump installation costs and a real-life case study and ground source heat pump reviews to showcase how a cascaded ground source heat pump system architecture fed by slinkies can effectively meet a high commercial heating and hot water load.

For more information, call sales on 0845 680 4328.

Schematic drawing*

*For illustrative purposes only

Costed example

Based on the above schematic, Kensa has calculated example costs below to illustrate the upfront finance required and the expected running costs and income generated via the Non-Domestic Renewable Heat Incentive (RHI) over a 20 year period (the duration of the Non Domestic RHI), compared to an LPG system. For a bespoke quote please click here.

Heat Pump Specification

System architectureCascaded central plant
Total heat pump capacity120kW
Equipment type3x 45kW Plant Rooms
Design conditions0/50°C
Potable DHW tempSpace heating only
Integral immersion heatersNo (DNO friendly)
Ground array typeSlinkies
Slinkies requiredx24, plus header pipework
Land area required6000sq/m


Total Project Costs, Savings & Returns vs LPG

 Self-FinancedFunded Split Ownership 
SystemKensa Ground Source Heat Pump & Ground ArrayLPG Boiler
Lifetime Expectancy: ApplianceUp to 20 yearsUp to 20 yearsUp to 10 years
Lifetime Expectancy: InfrastructureUp to 100 yearsUp to 100 years-
Carbon Saved (over 20 years)800 tonnes800 tonnes0 tonnes
Local NOx emissions*0kg NOx/y0kg NOx/y12.09kg NOx/y
Appliance & Infrastructure Cost**£87K to £115KDetails coming soon!£7K
Running Costs (over 20 years)***£350K to £400K£350K to £400K£450K to £500K
Servicing Costs (over 20 years)****£0£0£2K
Non Domestic RHI Income (over 20 years)*****£350K to £500K£0Not eligible
Net cost (after 20 years)******£15K - £87KDetails coming soon!£459K - £509K
*Costs are for the supply and installation of the Kensa heat pump and ground array only, and the supply and installation of the LPG boiler equipment only. Costs for supply and installation of internals such as radiators, underfloor and heating controls are not included, please speak to your plumbing contractor. **Based on electric at 15p/kW/hr and COP of 3. Based on LPG at 40p a litre and 85% efficiency ***Ground source heat pumps have no requirement for annual maintenance. However, it is good practice for the heating distribution system to be proactively checked and maintained to ensure optimum performance. ****The NON-DOMESTIC RHI is a 20 year index linked funding stream which assumes inflation at 3%. *****Net cost for LPG does not include an additional LPG boiler, which will likely need to be  factored in during the 20 year comparison period due to the LPG’s 10 year average lifetime expectancy.

Case study: Hevingham School, Norfolk

Norfolk County Council chose Hevingham School as the showcase site for its Classroom Of The Future. The Kensa 20kW Compact heat pump connects to underfloor heating with provision of hot water supported by solar panels and the water supplied primarily by a rainwater recovery system.

Key Facts

  • Newbuild school classroom;
  • 20kW Kensa Twin Compact ground source heat pump;
  • 100% space heating with underfloor;
  • Slinky pipes laid in 50m trenches under playing field.
Read more

Related Content

Blog: Cascaded ground source heat pumps

If a commercial premises has a high demand for heating and hot water, then modular cascaded ground source heat pumps provide an effective solution to meet the heat load of the property.