The most likely cause is a bad thermostat.
Immersion heater thermostat reset button.
I reset it to get a bath but a couple of days later it was up again and so on until now.
When the water temperature in your water heater exceeds 180 the red reset button also known as the high limit switch trips.
If so push that reset button as well.
Simply press the switch usually red in color to reset it.
If the button is lit up it means the switch tripped and needs to be reset.
There is probably a thermostat at the top of your electric water heater.
Your water heater reset button is a safety device that shuts off power to your water heater when the water temperature inside it exceeds 180 degrees fahrenheit.
I imagine all this can be is a separate thermostat from the adjustable one with a single upper.
To reset it you ll need to press the red reset button on the eco which is usually attached to the upper thermostat.
This is called the high limit thermostat that makes sure the water does not get too hot.
It gets tripped when the water temperature is in excess of that limit.
There are a few types of problems that can cause your water heater to overheat the water in the tank and when that happens the emergency cut off eco kicks in to shut down the appliance completely.
Immersion fitted in november and worked fine until a week or so ago at which point i found no hot water and the button up.
There may also be a lower thermostat reset button on the water heater.
Step 1 reset the button.
Ok but then what s causing the water in your water heater to get so hot.