I use dimmers as a back up to my t-stat. If the t-stat fails on or a probe gets pushed off then the flex watt still can only get so hot. As long as you test the setting before adding the animal and the room is a constant temp you can do it. Should you? Probably not the best idea but it can be done. As for not trusting them Idk why. Most are rated for a min of 300 watts. Even using 11 inch fw you would have to run 15 feet of it to worry about maxing it out. The summers I use are rated for 600 watts but I use one for every 10 tubs in conjunction with a t-stat.