Hotel has no reservations about Vaillant renewable energy

Vaillant, ground source heat pumps, water source heat pump
An unusual day’s work for Vaillant and installer Wheildons was installing heat-pump coils in a 5 m-deep lake without first draining it.

A heat pump drawing energy from a lake on the site of The Lake House boutique hotel near Windermere was installed without first draining the lake. Vaillant, which supplied a 10kW geoTHERM heat pump for this project, believes it is the first to be installed in the UK without first draining the lake. The heat pump draws heat from the natural Knipe Tarn to provide underfloor heating for the hotel.

The production of domestic hot water is support by five Vaillant auroTHERM vacuum-tube solar collectors to preheat water which is fed into a bespoke tank-in-tank system.

Using Knipe Tarn as a heat source was the idea of architect Ben Cunliffe, whose family owns and runs The Lake House. It was left to Mick Lloyd, director of installer Wheildons, and renewables experts from Vaillant to design a heating system and devise a scheme for the installation.

Mike Lloyd says, ‘Lakes are a good source of energy for heat pumps. In my opinion they are better than a horizontal layout and almost as good as a borehole. Knipe Tarn is around 5 m deep, which is a good depth for a lake heat-pump application. The installation has successfully provided heat during its first Winter and has provided the cosy environment needed for guests of this luxury hotel.’

The hotel uses water from Knipe Tarn for potable purposes, first cleaning and processing it through a filtration plant. Not only could the lake not be drained, but the collectors had to be installed without churning up the water or disturbing the lake bed.

The solution was based on four galvanised-steel frameworks, each with 200 m of collector tube coiled and fastened on to it. Each framework was floated out to the chosen location in the lake with weights to make it sink. Flotation devices were cut loose so the frameworks and coils could sink gently into the lake.

Two 50 m lengths of coil were left free on the collector frames to connect with a 4-part manifold installed underground on the lake shore and accessed via a manhole. Two larger pipes provide the connection to the house and are buried in a specially constructed trench under the front lawn, The heat pump itself is in an underground storage room. The system achieves a COP of about four.

The preheat store for the DHW system has a capacity of 350 l, and incoming water can often be as hot as 40°C.

For more information on this story, click here: October 2011, 120
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