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Heat Networks

Castle Ashby

Northamptonshire village makes the switch to a biomass heat network.

Castle Ashby | Energy from Waste

Project overview

The picturesque and historic village of Castle Ashby, Northamptonshire, is made up of 73 commercial and residential dwellings and dates back to 1306.

Many of the residents suffered from high energy bills from using a mixture of electric heaters, oil boilers and inefficient domestic gas boilers for heating and hot water.

Lord Compton, the owner of the Castle Ashby estate sought to reduce the carbon emissions of the village and lower fuel bills for the residents. He championed a sustainable district heating network as a way of removing the reliance on fossil fuels.

A biomass fuelled system was the obvious choice for Castle Ashby, due to the availability of good quality fuel on site. The installation of two Viessmann Pyrot woodchip boilers at 540 and 400 kW has resulted in carbon savings of 625 tonnes per year and greatly reduced fuel bills for Castle Ashby residents.

A sustainable and unique district heating network

As specialists in commercial scale biomass installations, Viessmann installation partner Clearpower Bioenergy Solutions was appointed as the contractor for the site.

After detailed consultation, the spacious yard of Castle Ashby Home Farm was chosen as the ideal location for the energy centre. Previously used as a milking parlour,
the yard now contains the heart of the sustainable heating system in two Pyrot biomass boilers, a unique top loader fuel storage and transfer system and two 10,000 litre buffer vessels.

Originally designed for the movement of compost and soil, the top loader system feeds woodchip from the estate into a common hopper that then feeds both biomass boilers simultaneously. This ensures a consistent supply of heating and hot water to the village, as a small percentage of woodchip is moved at any one time.

Hot water from the boilers is pumped into two 10,000 litre storage tanks and distributed across three independent heating circuits throughout the village, via highly insulated underground pipes.

Each Castle Ashby property has replaced its previous heating system with a heat interface unit, which records the energy used, allowing for effective monitoring of the district heating scheme.

The removal of these individual systems means that 68 boilers dispersed throughout the village, have now been replaced by two centrally located biomass boilers.


Overall the district heating system produces more than 2,500,000 kWh of heat per year for the village, resulting in a saving of 625 tonnes of carbon per annum. This
significant reduction in emissions points the way for sustainable villages across the UK, as woodchip biomass fuel takes over from oil and electric heating in Castle Ashby.

Ciaran Miller of Clearpower was pleased with the outcome of the project, as the boilers delivered the objectives set out by Lord Compton, at the conception of the scheme:

The quality of the Viessmann Pyrot boilers is unrivalled. As we design, install, fuel and maintain the system, we only choose products which we know are reliable and efficient.

Annual income from the RHI alone will total £90,000, with further funds generated from charging the residents a significantly reduced rate for heating and hot water.

Despite the large scale of the district heating scheme, the payback period of 15 years represents a future-proof investment by the current residents of Castle Ashby and
future generations to come.

Project details

  • Project year: March 2014
  • Equipment: 2 x Pyrot woodchip boilers
  • Rated output: Biomass boiler 540 kW
  • Biomass boiler 400 kW
  • Location: Castle Ashby, Northamptonshire
  • Contractor: Clearpower Bioenergy Solutions

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