Immersion Heater Thermostat

[GreyRog]

Our gas boiler is off at the moment awaiting repair, and we are using the electrical heater in the hot water tank.

Problem is that the water is getting too hot, so it's uncomfortable to wash and wasting electricity. I put a thermometer on the outlet pipe at the top, and it's reading 65 degrees. The thermostat (see pic) is at the lowest it will go, 50 degrees.

Does this mean the thermostat is faulty? Is it easy to replace without draining the tank? The thermostat body is quite loose, but there is no leak.

 

[Harry Bloomfield]

The thermostat body is quite loose, but there is

They are normally, able to be rotated, they just slide into a sealed pocket, and so easy to replace. You need to ensure it is the correct length, to match the element/pocket. The one you have, looks as if it is due for upgrade anyway - more modern ones, have a built in over-temperature trip, to prevent the water being boiled, and the header tank collapsing, spilling boiling water on anyone below.

 

[GreyRog]

Thank you, that's what I wanted to hear!
It's marked 18" so that must be the size.

Any suggestion for a replacement?

 

[Harry Bloomfield]

Any suggestion for a replacement?

https://www.screwfix.com/p/tesla-dual-safety-thermostat-18-/89445

 

[denso13]

a thermometer on the outlet pipe at the top, and it's reading 65 degrees.

It should be about 60-65 degrees.

 

[Agile]

It might be at the extreme end of the scale but it is still giving you the typical temperature that hot water tanks are set to.

When using water it is normal to mix some cold water with the hot to obtain water at the temperature that you want to use it at.

We cannot see the whole tank but most with the thermostat going downwards have an element about 27" or 32" long and a thermostat longer than 18". It is better to have a thermostat as long as the pocket will accommodate.

They are very easy to change. But as it takes 12 amps the screw terminals must be properly tightened.

 

[Harry Bloomfield]

We cannot see the whole tank but most with the thermostat going downwards have an element about 27" or 32" long and a thermostat longer than 18"

18" is the standard longest thermostat available.

 

[GreyRog]

I don't know how accurate my measurement was with a thermometer held against the pipe, but I do know the family have complained that the tap water is too hot.
Since this thermostat is not up the the latest safety standard, I'll be replacing it anyway.

Thanks everyone for your advice.