Another ? for ya, if I remember right, isn't there insulation similar in look like the hood pieces that sit on the tank or does it just bolt up into place. It's been so long, I can't remember anything I removed.
Try to find some of the frost gaurd stuff they use under the first couple rows of shingles. It's kind of sticky on both sides and works great. Find someone doing a roofing job or the lumber yard will want to sell you a whole roll.