This large (595 m2) and poorly insulated detached rural property is heated by a 45 kW Herz Pelletstar biomass boiler. The Herz boiler was installed to replace an earlier pellet boiler from an eastern European manufacturer that had failed after less than two years.


The boiler is installed in a large garage and supplies heat to a 1,000 litre buffer tank via a backflow circuit. The buffer connects to the existing heating and hot water system in the house via a 15m buried insulated heat main. The connection between the buffer and the vented system in the house is indirect via a plate heat exchanger.


With some modifications to the feed handling mechanism (switching from a rigid to a flexi-auger) we were able to reuse the 8 tonne pellet store. It was also possible to adapt most of the existing twin-walled chimney.