I have my venting pipe on the roof that freeze. It freeze close with condensation and I don't know why. I have to unblock it every couple of day when it is cold outside.

Sounds like you need Arctic Vents on your roof vents. I would put up an image, but this site has made it so difficult to do so that I cannot. Bing or Google Aortic Vents To check it out. Good luck, Tom

Since the site won't even let me edit my last post so that I may add an attachment I'll start a new post.