Innes House, Morayshire
195kW Woodchip District Heating System
Innes House is a large private house in the north of Scotland used for weddings and corporate entertainment. The ever rising cost of oil heating and a wish to maximise estate self-sufficiency drove the decision to invest in a biomass heating system.
The boiler and associated plant was installed in an extension to the stable block with a redundant storage room converted into a chip hopper. Dunster worked with the estate to design a system that minimised the impact on the listed buildings whilst ensuring maximum flexibility in fuel supply. Due to their proximity, it was decided to include three flats to provide lower cost heating to the tenants.
Fuel supply and chip handling
The first year’s supply of fuel was bought as bulk seasoned timber and chipped by a contractor into a bulk storage barn. Subsequent year’s supplies are being bought as bulk, freshly cut timber and seasoned on site. As estate woodlands are brought back into active management, these will ultimately be used to supply all the timber required to run the system. Chip is transferred from the bulk store in an agricultural trailer and is tipped into the trough of the ‘fast fill’ system which uses powerful augers and a ‘throw’ mechanism to load it into the fuel store at high level. Although the store holds around 3 weeks’ worth of chip at winter consumption rates, it is found most convenient to transfer about one 20m³ trailer’s worth each week as this fits in neatly with other tasks.
System design and installation
As the 280kW peak heat requirement of the house and flats significantly exceeds the 195kW capacity of the system, the main house boilers have been retained to provide peak-load capacity. Should demand exceed capacity, the oil boilers will fire up to ensure sufficient heat supply to all properties. Dunster’s system design forecast that biomass would supply 90% of the heat requirement with the balance of 10% being delivered by oil. However, by adjusting the way the house is heated to prevent spikes in demand, initial indications suggest that the oil boilers are not being used at all.
In addition to dramatically reducing the heating bills, the project has been the catalyst for regenerating forestry capacity on the estate.
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