The central heating option has the added benefits of back ventilation.

Four channels in the block provide the back ventilation. Air is drawn into these channels in the block through the ventilation grill at the base of the system and expelled through the expansion plate at the top of the chimney.

The interplay of the system components provides optimum flow conditions in the chimney. The upward air in the channels absorbs any moisture condensing in the chimney and transports it to the atmosphere.