All biomass boilers have some sort of flue system; there are typically two types:

Concentric

This system comprises two pipes one inside the other. The internal pipe takes the exhaust gases from the biomass boiler to the atmosphere and the outer pipe supplies air to the boiler. The majority of concentric flues are a maximum of four metres in length and have a wide range of flue bends and extensions. This provides greater flexibility in positioning your biomass boiler.

Twin Pipe

This system comprises two pipes. The first pipe takes the exhaust gases from the biomass boiler to the atmosphere and the second pipe supplies air to the boiler. This flue system is useful when the pipes need to be over four metres long. It also has a wide range of flue bends and extensions providing greater flexibility in positioning your biomass boiler. However, this may be less aesthetically pleasing due to the amount of pipe work on show.