Here are a few pics of our preheater.
60 feet of 3/8" copper tubing wrapped around our 6" stack, then wrapped with a piece of 7" stack. I will stuff insulation around the top and bottom and maybe thermal wrap the copper coming out to drip into our pan. I will put a valve at the end.http://www.mapletrader.com/community...&pictureid=176http://www.mapletrader.com/community...&pictureid=177
If it don't get hot now, it never will!!