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Ground Source

A ground source heat pump extracts 75% of the heat it delivers from the ground via pipes containing heat transfer fluid buried in the ground. This method is particularly efficient as the ground has a stable temperature, even in winter.

Extracting Heat From The Ground

The earth stores a vast amount of energy which it gets from solar radiation and rainfall. The ground receives up to 1kWh/m2 in winter and 5kWh/m2 in summer. To extract this energy from the ground we install what is known as ground collectors. These are made up of lengths of poly ethylene pipes containing a heat transfer fluid which is buried in the ground at a depth of 1.2m to 1.6m. The heat transfer fluid is pumped through the pipe work in the ground absorbing the heat which it deposits in the heat pump itself.

Horizontal Ground Collector

Horizontal collectors come in three main forms:
slinky trench system where coils on pipe are laid in trenches 1.2m wide by 1.2m deep. The trenches are between 30m and 50m long and the number of trenches depends on the size of the property to be heated;
horizontal loop system where long loops of pipe are laid in a large excavation measuring 35m to 40m long with the width depending on the size of the property to be heated;
pond loops are large bundles of pipe on a rack which are sunk to the bottom of a pond or lake.

Vertical Ground Collector

Where ground space is an issue, vertical collectors can be installed. Bore holes are drilled 150-200mm in diameter and depths of 75-150m. Loops of pipe are installed and the hole is backfilled with a thermally efficient grout. The number and depth of the bore holes depends on the size of the property to be heated. Vertical collectors are more expensive than horizontal but require less space and ground disturbance.