Immersion heater tripping RCD

[HazzaB]

Hi Guys,

My immersion heater seems to be tripping one of my RCDs.

If I have the switch (labeled Water Heater, directly next to the heater vessel) all other appliances on the RCD work fine and do not trip. As soon as I flick tha switch (even if it's not currently on a heating schedule) it trips the RCD instantly.

I'm pretty handy at DIY and on the tools but not really had to deal with heaters like this. What should be my first port of call? I have attached some pictures:

Boiler vessel:

Thermostat/element:

Switch/electrics by vessel:

Any recommendations would be very much appreciated!

Thanks,
H

 

[HERTS P&D]

New immersion is needed!

Andy

 

[HazzaB]

New immersion is needed!

Andy

I presume you mean the element? What's the best way to figure out which one I need?

 

[HERTS P&D]

This one:

Tesla Long Life Incoloy Immersion Heater & Resettable Thermostat

Suitable for use in soft and moderate water hardness areas. Conforms to safety standards effective April 2004.• Boss size: 2-1/4" BSP• 3kW• 240V• Total Length: 11"• Thermostat Length: 7"• 1 Year manufacturers guarantee• Copper pocketNot compatible with stainless steel tanks.

www.toolstation.com

Not a job for a first timer!

Andy

 

[pete01]

This one:

Tesla Long Life Incoloy Immersion Heater & Resettable Thermostat

Suitable for use in soft and moderate water hardness areas. Conforms to safety standards effective April 2004.• Boss size: 2-1/4" BSP• 3kW• 240V• Total Length: 11"• Thermostat Length: 7"• 1 Year manufacturers guarantee• Copper pocketNot compatible with stainless steel tanks.

www.toolstation.com

Not a job for a first timer!

Andy

Wonder how you did your first one.

 

[HazzaB]

Not a job for a first timer!

Andy

May I ask which aspect makes you suggest that? Researching online seems to be fairly straightforward. Main 'scary' bit is possibly tearing the vessel?

 

[Harry Bloomfield]

You will need the element, new matching thermostat and the special big spanner to fit the boss. A blow lamp, plus gentle taps with a hammer might help free it, if it's seized, and it will need to be drained first.

 

[pete01]

As above but don't drain first only drain when loosened.

 

[Harry Bloomfield]

As above but don't drain first only drain when loosened.

Good point - but he will not be able to drain the water from the cylinder, he will only be able to drain the tank and pipework which lies above the tank. Hence, expect some water to come out, once the immersion heater is released - have lots of towels ready to catch the few pints which come out.

 

[HERTS P&D]

Wonder how you did your first one.

Working with a plumber with over 40 years of experience.

Andy

 

[pete01]

Working with a plumber with over 40 years of experience.

Andy

Yes good point, I started doing them after seeing them done a few times, bit nerve racking the first few but not really brain surgery.

 

[flameport]

Researching online seems to be fairly straightforward.

It's straightforward if the old one unscrews properly the first time.
Everything online looks straightforward because people only show it when it all goes well - and those videos which show disasters are usually staged for maximum effect.

Main 'scary' bit is possibly tearing the vessel?

Could be, in which case it's new cylinder time.
Or the thread is seized and when unscrewing you are actually twisting the threaded boss out of the cylinder. If that happens, you won't know until it's too late.
Or the thread gets damaged so that although the old one can be removed, the new one won't screw in.