Junkers, a brand of Bosch Thermotechnology, presents Supraclass-SW, a new log boiler. The new Supraclass-SW replaces the 15, 20 and 25 kW versions of the predecessor with the same name, adding some extras that are usually only found in higher price categories. These include a controller to modulate the operation of the draft ventilator as well as optimised buffer management through integrated temperature difference control.
Supraclass-SW is available in two different output ratings: 18 kW for logs up to a length of 330 mm and 24 kW for logs up to a length of 500 mm. The log boiler can be integrated easily into a wood oil/gas boiler combination: when using hardwood - as recommended – the combustion time of about four hours makes it perfectly suitable as an addition to oil or gas. Supraclass-SW can also be combined with a solar system.
The primary and secondary airflows have been further improved in comparison to the predecessor and an easily accessible lighting flap is provided. These improvements simplify lighting the boiler and shorten the lighting procedure as well as the formation of a firebed. A modulating flue-gas fan automatically controls the combustion during operation, while the ceramic combustion chamber ensures optimum combustion of the heating gases. The fume extraction function allows logs to be inserted with the filling door open without heating gases or smoke escaping.
Thanks to the even combustion, the boiler achieves an efficiency of up to 86 per cent. The stainless steel lining on the sides of the filling room makes it particularly easy to clean. In addition, tar deposition is minimised. To minimize heat loss, the flue gas collector is equipped with additional heat insulation. As the primary and secondary airflows are controlled from the front during start-up, it is particularly easy to adjust the system to the fuel selected and the boiler is very narrow. With dimensions of 1430 x 640 x 790 mm (height x width x depth in the 18 kW version) and 1430 x 640 x 920 mm in the 24 kW version, both versions require only little space.
The new Supraclass-SW and the pellet boilers Suprapellets mean that Junkers offers a comprehensive concept for energy-efficient biomass heating for single- and two-family homes. After all, wood combustion is CO2-neutral, wood is available everywhere and can largely be sourced from domestic forests.