The Caleffi anti condensation unit connect between a biomass boiler and a direct or indirect heating system or domestic hot water system. The internal thermostatic sensor controls the return temperature to the boiler to avoid condensation build up. Ensuring that the boiler is at a high temperature prevents condensation from the water vapour contained in the flue gases. It can be used on central biomass boilers or residential biomass boilers, such as solid fuel or pellet stoves. The anti condensation unit gives the boiler a longer life and ensures greater efficiency.