European firm Windhager, Gloucestershire, U.K., has launched a Duowin combination biomass boiler that provides heating from both wood and pellets in one unit. A fuel-switching system detects when the wood gassifier is in burnout and switches to pellet operation, either automatically or at a chosen time.

 

 

Only taking up 4.19 cubic meters of space, it is available in either a comfort or energy-optimized form with a power boost function to meet short-term higher heat demands up to 56kW. With the energy-optimized version, the Duowin’s pellet operation is said to be up to 25% more efficient than conventional combination boilers. 

It is available in four models from 33kW to 56kW output, with a filling volume of 145 liters for 50 cm split logs and 164 liters of wood pellets. The feed can be either manual or fully automatic.

Within the unit, there are two independent heat exchanger systems that are claimed to give good reliability, but require less space compared with other combinations.

Both the wood combustion chamber and the stainless steel pellet burner bowl are non-wearing parts and are included in Windhager’s five-year warranty. Users can also upgrade at any time to the Duowin if they have Windhager’s Logwin Klassic log boiler.

The Logwin Klassic has a large filling chamber opening for good access with logs and a detachable ash pan for easy removal. The log boiler also has automatic ignition, so no kindling is required to start the boiler burning.

Starting price for the Duowin is £14,500 and doesn’t include VAT, installation costs, or other accessories. In a non-domestic installation qualifying for the RHI scheme, the payback for this installation can be as short as five years, according to the company.