The owners of this property decided to heat their newly self-built 5 bedroom home using a wood pellet fuelled 30 kW Herz Pelletstar boiler.


The boiler is located in a basement garage. Wood pellets are fed to it by vacuum transfer from a 4 tonne underground Geotank 8,000 pellet silo, which is buried in the garden.


The boiler supplies heat to a 1,000 litre buffer tank which is directly connected to a 3-zone underfloor heating system with some wall mounted radiators. DHW is supplied at mains pressure via a heat interface unit which includes a plate exchanger. A secondary circulation system minimises the hot water deadleg.


Pellet consumption is offset for much of the year by a 60-tube solar thermal collector connected to the twin coils in the buffer store supplying heat for DHW.


The heat generated by the boiler is measured by an Itron Echo CF plus heat meter with figures reported quarterly to OFGEM.