Immersion thermostat issue

spose

I have an issue with the immersion overheating the tank. I assumed thermostat was gone and replaced it but doesn’t seem to have made a difference. Have read through posts here for tank over heating but haven’t found any where changing them the stat didn’t fix it. Anyone know the likely reasons for why this is happening/didn’t fix it?

Lenar3556

spose wrote: »

I have an issue with the immersion overheating the tank. I assumed thermostat was gone and replaced it but doesn’t seem to have made a difference. Have read through posts here for tank over heating but haven’t found any where changing them the stat didn’t fix it. Anyone know the likely reasons for why this is happening/didn’t fix it?

Just to help understand;

Why do you think it is overheating?
Is this a new issue? I.e did it work ok previously?
What temp is the new thermostat set at?

John.G

If its a dual immersion then it should be wired like in the attachment.

spose

Seems to be wired right...pic attached.
It’s definitely overheating, the tank is close to boiling. I don’t know if it did work previously as it’s new to me.
Stat is set to the default 60.

iwillhtfu

spose wrote: »

Seems to be wired right...pic attached.
It’s definitely overheating, the tank is close to boiling. I don’t know if it did work previously as it’s new to me.
Stat is set to the default 60.

Have you tried turning down the temp setting 60 is very high.

John.G

They are normally set correctly to 60C (with spot of glue) and generally operate very close to this set point.
You could run some hot water off until you estimate its ~ 50C then slowly lower the setting to hear the stat clicking off or/and turn it up to hear it clicking in. The o/temp stat should also have operated I think at somewhere around 85C.

Also assume that the immersion is the only heating source in operation just now?.

Wearb

spose wrote: »

Seems to be wired right...pic attached.
It’s definitely overheating, the tank is close to boiling. I don’t know if it did work previously as it’s new to me.
Stat is set to the default 60.

That looks correct, but assumes that it's wired correctly back up the line.

spose

Thanks. Checking with a phase tester it switches elements ok but I’m not picking up anything live anywhere other than where the live is connected to the element. Should it not be live where it’s circled in red? Does this not suggest the power isn’t making it to the stat?

John.G

No, the stat is switching the neutral so no power there means that the stat is closed, if you were to remove the wire from the other end of the stat then you will see power, also, if you now turn the stat setting down to open it, you should see power as the neutral is now broken.
I'm not a great lover of phase testers but it should light up under the conditions I outlined above.

Lenar3556

iwillhtfu wrote: »

Have you tried turning down the temp setting 60 is very high.

You really want to be bringing cylinders up to 60 to effectively deal with legionnaires disease.

Lenar3556

spose wrote: »

Seems to be wired right...pic attached.
It’s definitely overheating, the tank is close to boiling. I don’t know if it did work previously as it’s new to me.
Stat is set to the default 60.

Nothing obvious there, could you get a photo of that flex connected to the switch?

Would be good to get a water temperature at a tap.

Is there steam pouring from the expansion pipe in the attic when the immersion is left on?

John.G

This stat has a hi limit stat incorporated in it and operates at 81C, the stat normal range is 40 to 70C.
https://www.advancedwater.co.uk/STOMEMO/A568-583-3101/11%20Inch%20Safety%20Rod%20Thermostat.pdf