A: If the shower is not heating properly then there only threethings that can be causing it not to heat.
1 One of the elements has failed
2 There is no power getting to one of the elements
3 The thermostatic valve has failed
If it is the elements I would expect a resistance between 11 and18 ohms depending on the output of the heating tank, it would also be unusualfor both elements to have the same resistance.
If one of the switches has failed and then there will be nopower getting to one of the elements this should be easy to check.
There is not much you can do to check the thermostatic valve otherthan if you know that everything else is OK then that will only leave thethermostatic valve.
Answered 97 days ago | The Doc