Probably both. If your tstat probe is mounted correctly outside the tub on the uth it is telling you what the uth is at. Using the temp gun inside the tub on top of a paper towel the temp gun will give you that temp. If the paper towel is not being weighted down and staying in contact with the tub floor it will not reach the same temp.
What is the temp of the tub floor? That is what you should be checking.
Reply With Quote