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Peterborough Fens

Location:              Thorney

Property Size:      325 m2

System Type:       A water source Stiebel Eltron WPF single phase heat pump

System Size:        13 kW

Heat emitters:      Underfloor heating, flow temperature 35oC

Extra features:     MVHR system, integrated water softener


This project is a new home created from a pair of farm cottages and substantially extended.

Our client and his wife were looking for an environmentally sustainable heating system for their new well insulated home. With high efficiency ratings and the preferential planning concessions heat pumps became the obvious choice. When it was discovered that a small lake in a former gravel pit adjacent to the house could be used as a heat collector this improved the financial viability. They also had concerns about indoor air quality so a Mechanical Ventilation and Heat Recovery (MVHR) System was installed to provide that indoor “fresh air” experience.

Water source heat pumps are rapidly gaining in popularity as they are a cost efficient way of heating a home. These are ideal for the rivers and pools found across the region. Water has a high specific heat capacity and is consequently able to store relatively large amounts of solar energy. So when there is a sufficient body of water, a pond collector is a simple and low cost way to extract heat and transfer it to the heat emitter system.

Having considered various options and established the general viability, we consulted our network of industry professionals to confirm the best approach for this situation. As the lake had sufficient depth, coils of plastic heat collector pipe were submerged and weighted down to rest on the quarry bed. The pipe was filled with a low toxicity heat exchanger fluid to safeguard any potential impact on the local ecosystem.

Stiebel Eltron are a long established German manufacturer who specialise in efficient, robustly engineered and reliable heat pumps. For the bespoke indoor plant room we specified a 13 kW heat pump with a 400 litre hot water cylinder and 200 litre buffer tank to optimise system efficiency. For maximum comfort levels and system efficiency underfloor heating was installed throughout. A screeded system for the ground floor and heat emitter plates on the first floor.

The client feedback is really positive, “It works well and the house is certainly warm, running with a comfortable background heat through the underfloor pipework and no need to rely on the timer at all yet. The plentiful instant pumped hot water has been very popular!”

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