Case study

Tove Valley Holidays

200kW woodchip boiler with 7,000 litre accumulator tank

Key facts


November 2013


Supply of hot water and heating to twelve new build, self-catering cottages in rural Northamptonshire.

Boiler and plant

ETA Hack 199kW biomass boiler and a 7,000 litre accumulator tank
in a purpose built plant room.


The boiler is set up to use G30–G50 woodchip. The fuel is bought by the estate in cord wood format and seasoned prior to periodic chipping.

Chip storage

Once chipped, fuel is stored within a large grain store and transferred into the purpose built fuel store monthly. The fuel store capacity of over 100m2 enables fully articulated lorry loads to be delivered if required.

Grant / Funding

The system was funded from estate resources and is accredited under the non-domestic Renewable Heat Incentive Scheme.

Savings / Investments

There were no existing fuel sources as this was a new build project. But oil or LPG would have been the only other choices. RHI will generate an annual income of approximately £23,000. The expected return on investment is 17%.

Dunster were approached by the construction company re-developing a series of disused agricultural buildings for Tove Valley Holidays. Involved at an early stage, Dunster were asked to look at the most economical way of providing heat and hot water across the site, whilst complying with the latest building regulations.

The development was to build twelve high-end self-catering holiday cottages with all heating and pipework to be concealed – a challenge with most walls being stone faced and the ceilings vaulted. The decision was taken to install a 199kW ETA HACK woodchip boiler for the entire site, located within a large stone built boiler house that would leave enough space for another system if the site was developed further in
the future.

Fuel supply and chip handling

The boiler was specified and commissioned to burn woodchip fuel. Fuel is supplied from a combination of timber harvested from the owners own land supplemented by further cord wood bought in. Timber is stored on site for seasoning and chipped annually by an external contractor. Woodchip is then stored within a large grain barn and then transferred to the fuel store by tele-handler and front loader. The fuel store is sized sufficiently to take a full articulated lorry load of woodchip if necessary.

System design and installation

The system has been designed to satisfy the heating and hot water needs of the twelve, two to four bedroom cottages, and a further three in the future development plans. Dunster designed the heating and hot water systems for each of the properties utilising the ETA BMS control package for the remote access and monitoring of the entire system by the management company. As the buildings are all linked it was decided to run internal heat main within the flooring of cottages and then install new high performance cylinders, manifolds and controls within specially designed riser cupboards.


Tove Valley Holidays have secured a strong stream of RHI income guaranteed and index linked for twenty years together with fuel costs below half of those achievable with LPG or oil. Further marketing benefits have been obtained by enhancing Tove Valleys environmental credentials.

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