Case study

Gilmour & Aitken Ltd, Scotland

500kW woodchip boiler

Key facts


March 2016


Industrial hard wood drying and heating of associated offices, warehouses and trade centre.

Boiler and plant

Froling Turbomat 500kW woodchip boiler with 15,000 litre Galu accumulator tank and 5m diameter agitator/auger fuel feed. The plant room and fuel store were adapted from existing, old timber drying kiln buildings which upon becoming redundant were being used for timber storage.


The boiler is expected to use around 290 tonnes of wood chip to produce around 870 MWh of heat per annum.

Chip storage

Adjacent to the plant room and chip hopper, space has been created to form a bulk chip store. Chips are transferred from the bulk store into the hopper using a telehandler with bucket.

Grant / Funding

The project was self-funded and is fully accredited on the non-domestic RHI scheme.

Savings / Investments

Income from the RHI and fuel cost savings are expected to result in a return on investment exceeding 20%.

CO2 saving

More than 190 tonnes per annum compared to a modern gas fired system.

Gilmour and Aitken is a family run timber merchant established in 1852. The company specialises in joinery hardwood for the UK market and heavy constructional hardwood for marine and civil engineering projects. They also have a trade centre on site which supplies timber related products to local small businesses and the public.

Dunster was contacted to determine the feasibility of installing a biomass boiler to replace the mains gas boiler heating the drying kilns and to provide heat to the offices, yard bothies and trade centre areas. Timber drying via kilns is a fundamental, but energy intensive, process in the preparation of timber for sale and the company aim was to become self-sufficient in heating fuel by using slab wood offcuts from timber processing. Dunster was quickly able to propose a biomass scheme to fulfil this ambition and provided a ‘one stop shop’, not only undertaking all the boiler and pipework installation, but project managing the associated joinery and building work and advising on RHI qualification and application. Dunster was chosen to deliver the project due to the professional, fully inclusive, nature of their quote and their ability to install the boiler within a tight timeframe.

gilmour and aitken

Fuel supply and chip handling

Offcuts from timber processing are chipped periodically by a contractor into a bulk chip store situated adjacent to the hopper and plant room. A telehandler with bucket is used to transfer chips as required from the bulk store to the hopper.

System design and installation

Dunster designed a heat distribution system which minimised disruption to the ongoing business but provides enhanced heating for the offices, meeting rooms and trade centre. The mains gas boiler has been retained as an automatic back-up system for the kilns providing a welcome level of redundancy which was not available in the past. The 15,000 litre Galu thermal store allows the biomass boiler to operate at peak efficiency even when demand is low in the summer or when the kilns or off.


Not only does the company benefit from substantial CO2 savings and a return on investment of around 20% but, instead of arranging to dispose of timbers slabs, they have become a valuable fuel resource. The project has also resulted in improved heating of the offices whilst the addition of heating in the trade centre allows long term storage of building products such as plaster board which used to deteriorate rapidly in the cold and damp conditions.

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