A ground source heat pump installation using boreholes for an extensive home renovation project.

The selected heat pump was a Stiebel Eltron WPF13S which was married to a 400ltr hot water cylinder and 200ltr buffer cylinder (to regulate the heating). Three 100m boreholes absorb energy from the ground.

Using the Internet Service Gateway (the internet monitoring facility that comes included with every Stiebel Eltron heat pump), we have been able to monitor energy usage from the heat pump. This shows that from the date of commission (31st August 2018) to 16th April 2019 (an eight-month winter period), the efficiency of the system was 4.48, meaning that for every kWh of electricity consumed by the heat pump, it produced 4.48kWh of heat energy to the building.

At an electricity price of 14p/kWh, the heat pump has cost the client just £1,470 (£5.76/day) for heating and hot water provision. This daily figure will drop considerably as we go into spring and summer months (expected to be just £2/day).

Heat is distributed throughout the house by underfloor heating and radiators, the latter being sized appropriately to run with a heat pump. Mechanical Ventilation & Heat Recovery (MVHR), also installed by Pure Renewables, ensures the internal atmosphere is well-ventilated – this reduces any condensation risk and also recovers waste heat to help further reduce heating costs.

The clients were very happy with the system and commented: “I would like to thank you for the service you have provided in advising and installing the ground source heat pump at our home. We are very pleased with it from all points of view and would recommend to anybody who is looking to do this to talk to you!”

The system was commissioned in April 2019.

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