The Technology

Heat Sources & Collectors

What's your source?

Kensa ground source heat pumps are designed to extract renewable heat energy from a number of heat sources providing greater flexibility, affordability and compatibility with a range of applications.

Heat energy (typically from the sun) is stored in the ground and water all around us, at a constant temperature all year round. Ground source heat pumps are designed to extract this heat energy via an array of collectors (sometimes referred to as ground collectors or ground arrays); whether this collector is a borehole in rock, slinky pipe in soil, or pond mat in a lake – Kensa has even designed systems to extract heat from sea water to provide heating to boats!

Things to consider

  • Water – If you are within reasonable reach (100m) of a water source (lake, stream, sea etc.) this should be your first option for a heat source due to waters exceptional thermal conductivity and lower installation costs.
  • Cost – Borehole drilling is the most expensive of the ground array options, but is the quickest and less invasive option.
  • Geology – The ground conditions and therefore conductivity of the underlying geology will influence the cost of the ground array.
  • Area – As a general rule, a garden area of at least 40m x 12m is required. Smaller gardens can benefit from borehole collectors.

Key things to remember about ground source heat pump collectors:

  • Collector arrays are sized to meet the heat needs of the building, not the heat pump.
  • All collectors have broadly the same performance.
  • A buildings thermal efficiency affects heat pump performance more than the type of collector.

Surface Soil: Home grown energy

1m below the surface the ground temperature remains a fairly constant 8-10°C all year round. This makes it an excellent renewable heat source for ground source heat pumps; indeed, surface soil was the first heat source used to work with ground source heat pumps, hence their name.

To extract the heat from surface soil, a network of ground collectors (or ground arrays), consisting of a series of pipes, is buried in the ground in trenches to a depth of 1 – 2m. Typically consisting of coiled pipe, collectors of this nature are referred to as ‘slinkies’.

Read more


Solar energy stored in surface soil dissipates through the many rock layers beneath our feet to form a very stable heat source. Depending on the make-up of the geology, this can provide an excellent heat source for ground source heat pumps

Boreholes are the collectors used to extract heat energy from rock for ground source heat pumps. To extract the heat from the rock, straight pipes are installed down 60-100m deep by 150mm wide drilled holes, making them a very discreet and compact solution when space saving and minimal ground disruption is a priority.

Read more


An aquifer is an underground layer of water-bearing permeable rock from which heat energy in the groundwater can be extracted using a borehole collector.

Read more

Non-tidal water sources

Water is an excellent conductor, and this is especially useful when it comes to extracting heat energy from it. Water source heat pumps typically see 5ºC – 6ºC higher return temperatures to the heat pump than other heat sources, further enhancing the efficiency of the heat pump.

Non-tidal water sources include lakes, ponds, streams, and rivers, all of which are used very successfully by Kensa to provide heating and hot water to residents on the shoreline.

Pond mats are typically utilised to extract the heat from non-tidal water sources, however methods using boreholes and submerged ‘open loop’ pipework are also used to great success.

Read more

Sea water

Sea water provides the same qualities as non-tidal water sources, and so sea-source heat pumps are particularly useful in marine applications, for example heating or cooling marine vessels and boat sheds.

Should a domestic or commercial land based application require heating or cooling from a sea water source, consideration of the tide plays an important part in the selection of the water collector or the required periods of heat demand.

Pond mats are typically utilised to extract the heat from the sea, however methods using boreholes and submerged ‘open loop’ pipework are also used to great success for sea water source heat pumps.

Read more

Heat networks

Heat networks (also known as district heating) are particularly useful in commercial scale applications, for example in housing developments or business parks.

Historically heat networks were viewed as problematic with respect to split-bill issues and varying heat demands. Kensa have identified and resolved this imperfection and pioneered the development of a system architecture for ground source heat pumps known as ‘micro heat networks’, which attracts an income through the Non-Domestic Renewable Heat Incentive (RHI) for both new build and retrofit applications.

Traditionally rock is utilised as the heat source via borehole collectors for use in heat networks,  however water sources could equally provide significant groundwork savings and deliver even more efficient results.

Read more
I knew that ground source was a great technology for extracting the natural heat that’s available from the environment to provide a completely green heating system. The good thing about the pipes being in the lake is that water has great conductivity meaning we are able to extract heat sustainably throughout the winter to keep the house perfectly warm.

Mr Clarke, homeowner

Get a free quote from Kensa Heat Pumps

How can we help?

What are you looking for?*

Would you like us to forward your enquiry to a recommended Kensa Partner Installer to contact you direct?*

Your Details

Your Name* Email* Address 1* Address 2 Postcode*
Company (If relevant) Industry Type* Region* Telephone*

Your Project Details

Is your project site address different to details provided in Step 1*

Project Site Address 1 Project Site Address 2 Project Site Postcode Project Site Region
Your role in the project*

Project stage*

Size of property (m²)* House type*

Property age*

Project type*
No of properties*

Likely start date*

No of bedrooms*

For an accurate quotation we require copies of your plans: (PNG, JPG, PDF. Max 6MB)

Loft and cavity wall insulation installed?*
YesNoNot possible

Domestic hot water production*

Available ground area (m²) Preferred collector

Heating distribution*
Current heating fuel? Mains GasElectric StorageLPGOil
SAP available?YesNo Ground floor construction

First floor construction

Second floor construction
How did you hear about us?* Add any additional comments?
Please tick box to show that you accept the Terms & conditions of our site.
Any information you supply will be held in accordance with the Data Protection Act 1998.
If uploading files please be patient with page load times.

Installer Enquiry Form

This form will be submitted to Installer Directory

To receive a comprehensive quotation from Kensa please provide details of your project in this form. Mandatory fields marked with a * are required for all quotations.


Company Name (if relevant)

Industry type*

Address (line one)*

Address (line two)*





Project name*

Your role in the project*

Project type*

Project stage*

Likelihood of heat pump going ahead*

Likely start date*

How did you hear about us?*

Add any additional notes here

Size your project:*

Property size is required for all quotes. Please select and provide your property size using one (or all) of the following options:

House size (m²): (Unsure? Map yours here & multiply by storeys)

Upload plans:

House type:*

Number of bedrooms:*

Loft and cavity wall insulation installed?*

Property age:*

Heating distribution:*
Underfloor throughoutRadiators throughoutRadiator/underfloor mix

Domestic hot water production:*

Available ground area (m²):

Preferred collector:

Current heating fuel:
Mains GasElectric StorageLPGOil

Ground floor construction:

First floor construction:

Second floor construction:

SAP available:

Information you supply will be held in accordance with the Data Protection Act 2015.