Knowle Manor, Somerset
195 kW Wood Chip District Heating Scheme
Knowle Manor is a substantial house with 19 en-suite bedrooms and an indoor swimming pool which is available to rent for large groups and corporate events. Prior to this installation, it was heated by a combination of oil and LPG boilers, the cost of which was proving prohibitive. The owners decided to utilise a large, redundant, agricultural building as a wood chip store and boiler room; it was also decided to provide heat through a ‘district heating system’, not only to the Manor, but also to two cottages. Additional capacity has been retained in order to provide heat for two barns which may be converted in the future.
Fuel supply and chip handling
Seasoned waste timber is purchased from a local sawmill and delivered in bulk to the estate where it is chipped by a contractor directly into the bulk chip store. The size and layout of the store mean this operation is only required about every six months. A tractor and loader is then used to push chip from the bulk store over an internal wall into the large hopper where it is fed into the boiler by a 6m spring arm agitator. The size of the hopper means that this latter operation is undertaken approximately monthly.
System design and installation
The system was designed for 100% of heat and hot water to be provided by biomass fuel. The heat is transferred from the boiler room to the Manor and adjacent cottages by 260m of pre-insulated district heating main. The 5,000 litre accumulator tank stores enough heat to allow peak demand to substantially exceed the 195Kw rating of the boiler; it also allows the boiler to operate efficiently by burning for long periods rather than ‘short cycling’.
In addition to dramatically reducing the heating bills for the properties involved, the project has further contributed to the ‘green’ image of Knowle Manor.
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