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.

Example: Schematic

For illustrative purposes only

Example: Project & Finances

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

 Kensa Ground Source Heat Pump & Ground ArrayLPG Boiler
Lifetime Expectancy: ApplianceUp to 20 yearsUp to 10 years
Lifetime Expectancy: InfrastructureUp to 100 years-
Carbon Saved (over 20 years)800 tonnes0 tonnes
Appliance & Infrastructure Cost*£87K to £115K£7K
Running Costs (over 20 years)**£350K to £400K£450K to £500K
Servicing Costs (over 20 years)***£0K£2K
Non Domestic RHI Income (over 20 years)****£350K to £500KNot eligible
Net cost (after 20 years)*****£15K - £87K£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: Hornsea Garden Centre

Hornsea Garden Centre near Hull has three Kensa Plantroom heat pumps installed in a cascaded system to provide heating and hot water to a large new-build extension with 30,000 sq ft of retail space and a café kitchen.

Key facts:

  • New-build extension providing 30,000 sq ft of retail space;
  • Main building upgraded to underfloor heating;
  • Cascaded system architecture;
  • 2x 45kW Plantroom Heat Pump providing space heating;
  • 1x 25kW High Temperature Twin Compact Heat Pump providing hot water;
  • 24x 50m slinkies located under nearby field;
  • System contains 7250 litres of water and 1450 litres of antifreeze.
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Case Study: Todridge Farm

The owners of Todridge Farm had four 21kW Kensa Hybrid Heat Pumps installed in a cascaded system to cover the high demand for heating and hot water in their six bedroom farmhouse and four adjacent cottages.

Key facts:

  • 6 bedroom farmhouse and 4 cottages – 700m²
  • Displacing oil heating
  • x4 21kW Kensa Hybrid Heat Pumps
  • Cascaded system architecture
  • Pipework sunk into flooded marshland
  • Funded by the Renewables Finance Loan and Non Domestic RHI
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.