Gotta agree with Lawrence here. As you've already experienced, those t-stats are notorious for failure. But better to find it out in an empty tub, then have it fail after you've already put your buddy in there.


If you're stubborn ( ) you can just exchange it for another one...and keep trying them until you actually find a working unit. But I think you'd be much safer just getting your money back, and then going to Home Depot or Lowes and getting a lamp-dimmer-switch. You'll have to monitor your temps frequently and adjust as necessary...but in the meantime, you can save up for a more reliable t-stat like Johnson or Ranco.