I have a coal effect gas fire. Notice during the recent cold weather
that when the gas fire is not on there is a considerable down draught
which brings in a lot of cold air. Looking at my chimney pot I notice I
don`t have a cowl on it. Looked at ebay and notice there are a lot of
different types.

Has any one recommendations which would be the most effective in
preventing a down draught but still keeping a good enough draw . If so
besides ebay where can I obtain a good anti down draught cowl.