Fix the occasional downdraught in the chimney at our end of the house. Building it up above the roofline is implausible. Any opinions on the relative merits of various types of anti-downdraught cowls, like these?
http://www.ohlimited.co.uk/index.htmhttp://www.hotline-chimneys.co.uk/cowls_stationary_downdraught.htmhttp://www.hotline-chimneys.co.uk/cowls_revolving_downdraught.htmhttp://www.fluesystems.com/cowls/index_staticantidown.htmhttp://www.fluesystems.com/cowls/index_revolving.htm(The other chimney in the house is used less, and is higher, and isn't chilled by being on an end wall.)