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Farlington School – installation of two ETA 199 kW Wood Chip boilers with 10,000 litres of accumulator capacity in purpose built unit

Farlington School is an independent day and boarding school for girls near Horsham in West Sussex.

The Main school building is a Jacobean mansion set in beautiful Sussex countryside.  It is off the mains gas grid.

Forest Heat Energy Ltd. were contacted in early 2014 by Reenergise Group, who are a financing and consulting house specialising in renewables.

We were asked to work up a proposal to replace the school’s reliance on kerosene heating oil-fired boilers to benefit from lower cost wood fuel and the Government Renewable Heat Incentive Scheme, whilst also reducing their carbon footprint.

After an initial walk round inspection and further visits it was clear that a new, stand-alone boiler installation with an integral fuel store and a District Heating (DH) pipe network would be required to serve all the buildings. The existing oil boiler room was in an inaccessible basement.

Further meetings were convened by Reenergise with the School Management resulting in an initial specification and a site for the new boiler house.

The challenge was to come up with a new building that did not impact negatively on the listed main building and which would be acceptable to Horsham District Council’s planners. The location also had to be convenient for fuel deliveries and an economic, suitable underground DH pipework system to reach all the other four modern buildings, including the large sports hall.

Forest Heat Energy Ltd. designed a system which linked all the buildings, including being fed through to the old boiler room via a very constricted roof skilling using 4” steel flow and return pipes. A structural engineer was retained to ensure that this weight would be safely supported. 


With a total, estimated annual heat load of 675,000 kW/hours and a total existing oil boiler capacity of 642 kW we recommended two ETA 199 kW chip-fired boilers with 10,000 litres of accumulator capacity which could be operated sequentially or in tandem and should the capacity be inadequate in severe cold weather, then one or two of the four oil fired boilers could assist (so far, this has not been necessary).

This recommendation offered a more economical installation with maximum flexibility and the ability to have only one boiler down for servicing at a time.

It was considered that a 350 kW ETA was too small and a 500 kW ETA too large.

The school advised that one of the teaching blocks had never previously achieved a comfortable temperature, we have now solved this with our installation.

As part of our proposal we provided a design for a new low rise building of adequate dimensions clad in Eternit cement wood effect ship lap in colours to match the existing brickwork design of the other buildings, this would include the chip store.

Forest Heat Energy provided a quotation for the entire job.

We were selected as the desired installer in April 2014 with the condition that works would only be permitted in school holiday breaks, so the first job on May 24th was to trench and install the DH pipework and back fill for safety. Further work could not commence until July.

The erection of the new building and the full installation was carried out in August and completed by the Autumn term start. The system was commissioned in early October2014.

Initially the school had decided to have pellet boilers but after re assurances from our sister company Woodmancote Contractors that quality, timely wood chip deliveries could be made, they accepted that the lower fuel costs combined with the Renewable Heat Incentive payments would effect a shorter pay back of their investment.


RHI payments were calculated at approximately £30,000 p.a. based on 675,000 kW/hours and woodchip would cost roughly £10.000 less p.a. than pellets.

The school were also pleased to know that there would be a carbon saving of some 230 tonnes per annum and that wood chip was a much more sustainable fuel, thereby enhancing their environmental credentials.

Reenergise acted as Project Manager, organising progress meetings to ensure everything kept on track. They also made the School’s RHI application, with our assistance on the technical issues.

This has been successful with quarterly payments now being received.

The total cost of the installation was approximately £250,000 excluding VAT with a pay back estimate of 4.8 years.

The recent drop in oil prices will be more than offset in the longer term by the overall RHI return of some £600,000 over the 20 year Scheme period.

It is important to stress that the school committed to this conversion to a renewable heating system in order to benefit from the attractive RHI Scheme which is aimed at large heat users  who are burning fossil fuels, however wood chip fuel is still cheaper than oil and gas.

For further information or to understand how your business may benefit from a biomass heating system, please contact: John Penfold, Director, Forest Heat Energy Ltd. Tel: 01243 543036 Email: john@forestheatenergy.co.uk