Abstract: A biomass fired boiler having a series of inverted U-shaped exhaust gas flues. Water from a collection tank is pumped and sprayed onto deflection plates in the towers. The exhaust gases progressively commingle with the droplets to extract heat energy and collect contaminants at the tank until all the smoke has been absorbed into the water. The heated water is re-directed through a thermal exchanger of the heat transfer system and heat energy is reclaimed. Floating and/or suspended contaminants are filtered and/or collected and appropriately removed and/or incinerated.