Thanks guys.

Kitedemon. I realize the ambients are going to be a bit of a struggle. I may have to put a door in the whole rack to keep more heat in. Of course it will be ventilated. I just wonder if I should put and extra shelf at the bottom to sandwich some insulation to keep any cold off the bottom of the rack. It will be constructed from 5/8" melamine. I am told it holds heat pretty good from those into situation. That was a previous thread, before I decided to build the rack.

I like the aluminum tape idea to avoid the hit or cold spot on the tape. Also I think as long as the probe is a constant it will still regulate the same as if it was sitting on top just slightly different temperature setting. I plan on running the rack in the coolest spot in the house for a week ( worst case scenario) and then move it and run it in where it will stay.

One last concern is the soldered ends on the tap. They will stick up a bit too. I am going to place the solder joints at the back. May be I will have to cut grooves for those too. I was going to se rails but I don't wan heat to escape. I want to keep as much heat tape in contact with the tub as possible.