I assume you mean thermostat. Where does the probe for the thermostat sit? It should be on the heat tape.
There is no way to know what the temp is unless you measure it inside the tub. I run my belly heat at 102 degrees to reach a hot spot in the tub of 90 degrees.
is 90 good for a baby ? i just put another digital thermometer inside the tub now it says it was at 80 then it went to 89