A: The things to check first are.
1 That the main valve coming into your house is fully open.
2 Then check that the valve on the line to the shower is fully open.
If these valves are not fully open then there may not be enough water
getting to your shower to open / close the safety device that allowspower through to the elements
If these are OK then youmay have a faulty Thermal Cut Out
A faulty TCO will have no continuity across the twoterminals (The black thing on top of the heating tank)
Therefore a good TCO will have power at both connectionsand a faulty TCO will have power at only one.
(The function of the TCO is, if the water over heats itcuts the power off to the elements)
See Video.
http://www.youtube.com/user/showerdoc#p/u/2/_zi8JbEMYMs
Answered 123 days ago | The doc