The effectiveness of anti-downdraught domestic chimney pots in preventing smoke blow-back: Fid-Bau Portal

The effectiveness of anti-downdraught domestic chimney pots in preventing smoke blow-back

Carpenter, C.J.

AbstractThe problem of smoke-filled living rooms appears to have remained untackled since Count Rumford's contribution in the 1970s (Sir Benjamin Thompson, Count of Rumford, Chimney fireplaces, with proposals for improving them to save fuel; to render dwelling houses more comfortable and salubrious, and effectually to prevent chimneys from smoking. Supplementary observations concerning chimney fireplaces. In, Essays, Political, Economical and Philosophical, T. Cadell, Jr., and W. Davies, 1796). Anecdotal evidence abounds that the problem is still very real today.Seven antidowndraught chimney pots produced by Hepworth Clay Products Ltd. and one standard pot for reference were wind tunnel tested to evaluate their effectiveness in preventing smoke blow-back. Tests were done at a range of angles of elevation and depression of the wind, as occurs when a vertically rotating turbulent gust passes over a pot. All but one (the H-pot) were found to be susceptible to blow-back in severe downdraughts. In moderate downdraughts, most effective were the multilouvred pots, followed by the horned pots.An additional aim was to devise an improved pot which would be effective under all conditions, aesthetically inoffensive and economically viable. Successful preliminary tests were made on a retro-fit modification to the ‘top-of-the-range’ pot (which unmodified actually performed worst of all), and further development of the concept is planned.