Ground source heat pump for listed Hampshire Manor House

Our client on this project are the owners of the Manor House, situated outside Southampton, which dates back to early 1800 and is Grade 2 listed. The property has an adjoining Annex which has recently been converted with a view to renting it out.

The client was keen to replace the existing oil boiler with a renewable energy solution to cover all heating and hot water for the Manor House and the Annex.

The results of our initial survey showed that the combined heat loss of the two buildings was 24kW. There was a single phase electrical supply and existing radiators were sized to work with a high flow temperature.

The Manor House

Any solution would have to exclude an air source heat pump as installation of these is not permitted in listed homes. Our proposal was for a ground source heat pump solution harnessing energy from the ground in an adjacent field. This meant upgrading all radiators so that they would heat the rooms with a lower flow temperature from the heat pump of 55°C.

The plantroom in the basement

The system consists of Twin Stiebel Eltron WPF 13S ground source heat pumps with a combined total output of 26kW and 2 x 300 litre hot water cylinders. A suitable plant room was created in the basement of the house.

A total of 1500m of ground loop pipe with a water and antifreeze mix circulating through them collects the heat energy from the field and brings it back to the heat pump where it activates the refrigeration cycle at the evaporator.

Narrow trenches excavated by the Ditch Witch and ready for the ground collector pipe

The impact on the field of the excavation for the ground loop pipe was minimised by using a Ditch Witch trencher (pictured below) which keeps excavated material to a minimum.

Sunstone Energy designed, installed, commissioned and project managed the project.

The system was designed to comply with the requirements of the Non-Domestic RHI (Renewable Heat Incentive) as the Annex is to be rented out. The estimated income from the RHI is a total of over £80,000.00 over a period of 20 years. RHI payments are made against actual meter readings.

The anticipated running cost for heating and hot-water for BOTH The Manor House and Annex is £2,791.00 per year (approx £232.00 per month).