Ground Sourced Heat Pumps

Improve the efficiency of Ground Sourced Heat Pumps using EndoTherm
EndoTherm for Ground Sourced Heat Pumps

How Do Ground Sourced Heat Pumps Work?

Ground Sourced Heat Pumps (GSHPs) use pipes buried underground to extract heat from the ground.

The typical GSHP system contains a loop of pipework containing a mix of water and antifreeze (usually glycol based) that absorbs heat from the ground. This heat is raised internally by a compressor, which can then be used to heat radiators, underfloor and warm air heating systems in a property.

The compressor which heats up the water in a heat pump is powered by another source (typically electricity). The ratio of energy input compared with the heat output is called the ‘Coefficient of Performance’

Traditionally for every kW consumed by the heat pump, 4 kW of energy (heat) is created.

How does EndoTherm improve the efficiency of a GSHP?

The Coefficient of Performance is critical because, although a heat pump can be efficient, electricity is more expensive than gas. If you do not get a high Coefficient of Performance from your heat pump it could be cheaper to use a gas boiler for heating. GSHP manufacturers constantly battle to improve this coefficient to make their heat pumps more efficient.

EndoTherm acts as a heat transfer modifier in GSHP and reduces the surface tension of the water within a heat pump. A lower surface tension correlates to a higher surface area that the liquid of the GSHP can touch within the pipework, which increases the absorption of heat in the ground loop.  EndoTherm ultimately improves the Coefficient of Performance of the product and increases the efficiency of the GSHP system known commonly as the Seasonal Performance Factor (SPF).

EndoTherm, installed into the circuit of my Ground Sourced Heat System, saved me over £2000 on electricity in the first 6 months.

Estate Owner

Double Up with EndoTherm

Install EndoTherm in the Ground Source Heat Pump Circuit AND the Radiator Circuit to maximize your potential savings!


65 litres of EndoTherm was installed into one of the largest stately homes in the UK. The estate, which contains over 200 buildings and monuments is Grade I listed and means the energy saving methods available to the estate managers are limited.

2 x 110kW GSHP’s were installed under a 3 acre lake adjacent to the estate in September 2009 and EndoTherm was installed into the Primary loop in July 14.

A 6 month trial until January 2015 identified a 16.1% saving (compensated with degree days) compared to the year before. This represented an actual saving of over £2000 and a ROI of about 1 year.

How Much EndoTherm do I need for my GSHP Circuit?

This will depend on the volume of liquid flowing around the system. Typical installations need 1% EndoTherm with every 100L system volume.

Is EndoTherm Safe To Use

EndoTherm is non corrosive and proven to perform well with glycol based mixtures (typically found in GSHP circuits)