Brent,
Great post and thanks for the explanation.
Not suffering severe winters here, I had not heard of this technique until I saw the pictures on Walter Pall's Webpages/Blog.
http://walter-pall-travelogues.blogspot.com/index.html
Pity we have just gone on a Water Meter at home, but doubt I will ever need to run such a system here.
Regards,
Ian.