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 :-)
--
derek