Box preventing downdraughts in a chimney - exhaust flow warm downdraught so that it rises with the exhaust

摘要

The box is located near the top of the chimney and is rectangular with an inlet from below entering to one side of the base (3). The outlet is situated at the other end of the box in the top face (8). The gases flow up the chimney (11) and diagonally across the box (6) leaving by the outlet. Down draughts come into the box through the outlet (12) and circulate in the box. They are warmed by the rising gases (13) and return from whence they came. The lateral distance between the inlet and outlet pipes must not be less than the diameters of the pipes.