Water heater tripping circuit breaker

[Zentachi]

Hello everyone,

Just moved to a new property and I have noticed the following problem.

The property is using a gravity system.
The boiler is connected with a honeywell thermostat to the water cylinder (indirect water heating).

However, it seems that the cylinder have on top an immersion heating element. When I press the switch to turn that on, it trips the circuit breaker. Is this normal?

 

[AndyPRK]

No.

The immersion requires replacement.

This is your back up if the boiler fails

 

[Zentachi]

No.

The immersion requires replacement.

This is your back up if the boiler fails

Thanks Andy for the prompt reply. I thought so.
I do have a multimeter, do you know what I should check just to make sure that the problem is with the immersion?

 

[AndyPRK]

It’s not not something you can easily check.

Just check the wiring looks ok and not trapped

 

[ericmark]

I would guess it is the RCD tripping, to test the RCD needs a special meter, and to test the immersion heater insulation also needs a special meter, if it is the MCB tripping again looking at 16A plus and a standard multi-meter is unlikely to be able to handle that current, you would need a clamp-on meter to measure current, an insulation meter that uses 500 volt to test insulation, and a RCD meter which times as well as putting a load on the RCD to test it.

The fact you ask the question I would say you don't have the skill to safely test the immersion which is likely failed anyway, even renewing the immersion can easy rip the tank, so I would suggest getting some one in to change it who knows what they are doing, and has insurance should it all go wrong.

 

[Zentachi]

Many thanks for the advices.

Ericmark it is the RCD (If I understood it correctly) that it is tripping. Power to the house turns off.
With the immersion heater on, you cannot press back to on.

I found the following video, which explains how to replace it in the exactly same cylinder I have.

However, I might not try it and get a plumber to do it per your suggestion.

This is how it looks like. The immersion heater is just for backup right?
I guess no need to replace it immediately and can have it turned off.