Is my immersion heater thermostat corroded?

[hdp]

Hi

A plumber took a quick look at my immersion heater thermostat on my thermal bank water heater (during service check up) and told me its corroded and needs replacing. It's for the boast (which I don't use) on a 5 year old heater. I took a couple of photos which shows both thermostats which i post below. He quoted me £120 for the part, when I know I can buy it myself for less than £25.

Appreciated if any expert can help identify if he is correct and advise if it's necessary for this to be replaced.

Many thanks in advance
HDP

 

[Burnerman]

It looks like there has been some localised overheating there at some time....maybe the terminal screw was a little slack?
I'd renew it.
John

 

[footprints]

Yes as said looks like a loose connection or faulty insulation causing arcing replace it but £120 no way!
Take him longer to write out a receipt than to swap a thermostat rod!

 

[hdp]

That's for the part (I've now ordered that myself). He said the whole tank needs to be drained first. At least 2 hours of labour on top and another call out charge.

 

[hdp]

This is the heater: http://www.heatweb.co.uk/uploads/files/brochure-pandora.pdf

 

[Burnerman]

The tank has to be partially drained to replace the heating element, but the thermostat lives in its own pocket alongside, and just pulls out.
John

I'll edit this one as I've no knowledge of this type of system at all.
J.

 

[ree]

You are replacing the stat DIY but back in the day we would always replace the Imm heater and stat at the one visit - sods law rules.

 

[hdp]

I think its the Immersion Heater that needs replacing rather than the thermostat

Red one: http://www.plumbcenter.co.uk/en/hea...s/wired/sunvic-vkl-2351-immersion-thermostat/

Black one: http://www.plumbcenter.co.uk/en/hea...nvic-vk-4351-immersion-thermostat-11-80-190f/

 

[JohnD]

You said earlier that the thermostat (might) have a problem; now you say the heater element.

What caused you to change your mind?


Did he do an electrical insulation test or an earth leakage test?

 

[hdp]

It's called an immersion heater thermostat in the link (red one). That's the one he's saying needs replacing.

 

[JohnD]

Five minute job for a competent DIYer, plumber or electrician. You must of course turn off the electricity and test for dead.

If you are replacing a heater element (significant job) it makes sense to change the thermostat at the same time; but it makes no sense the other way round.

 

[hdp]

From the links which one do you think is which?

 

[JohnD]

The part no on the red one in your pic matches the one I see on the vendor's catalogue.

However I see only heat damage, I see no corrosion.

I don't understand the story, unless there is something I have missed.

 

[hdp]

That's why I'm posting to get an opinion if it needs changing. Plumber said he saw a drop of water coming out and then seeing only what I posted he that immersion is corroded and needs replacing.

 

[JohnD]

I can't see any trace of water. Can you?

If it is leaking, yes, it needs changing.