alot of ppl that talk down on belly heat have never tried it.
i had a belly heat rack that went wrong. lucky i didnt lose any snakes. but i have 3 tubs with holes that are 3" wide and 12" long in them now.
also back heat doesnt work if your rack is poorly made! the tubs have to fit you cant have 2" of space on each side of the tub and expect much