"Derek Broughton" wrote in message
...
News wrote:

I haven't a clue (and don't really care) if Nick's idea is sound, but
his
objection to a 4" pipe under the ridgeline of a roof certainly is.

Only in Canada type of climates.

You're wrong there. The majority of people reading usenet are in North
America. The majority of North America is subject to extreme freezing -
ie, all of Canada except the lower BC area, all of the American northeast
&
midwest, the plains states down to north Texas and all the mountain
states.

I know, a 4" pipe under _your_ roof ridge should be fine, but you're
practically in the tropics :-)

England in the tropics? Well if it stays below freezing all day, it is a
very cold day. In Winter, dropping below freezing during the night is
common.

Well the UKs most northerly part, is further north than the most southerly
point of Greenland. The most southerly, the Scillies, never gets frost. We
will be quite mild, yet on that same latitude where polar bears roam in
other parts.