Immersion failing

[Keepinghouse]

Hi guys,

I posted 2 months back about the same issue, not sure if im supposed to make a new post about it or not.

basically my immersion heater (side mounted) keeps failing every 2-3 months. I have an ideal stainless steel cylinder with an immersion mounted on the side.
the failure is the same every time- water starts getting into the thermostat tube and causes the rcd to trip.
the last time i replaced the immersion, i noted the earth connection at the timer switch was not connected properly and i thought poor grounding was the root cause.
unfortunately this hasnt worked.. im on my 4th immersion in under a year.
Any help would be massive.

 

[mikehammer69]

Never heard of this problem . Are these different brand heaters

 

[CountryFan]

Are you in a hard water area?

 

[ericmark]

Is something causing the water level to drop?

 

[Johntheo5]

Can you post a photo of any one of the failed immersions after removal concentrating on the pocket that the thermostat rod is inserted in, showing any visible signs of corrosion, cracking, etc.

Have you, as suggested in your other thread, tried a Becker Immersion??

 

[Daveydub]

I am on my 4th thermostat fitted to a new immersion fitted in August last year.
The immersion was a Tesla and the replacement stats were all Tesla.
Looking for an alternative make I noticed that Wickes were selling off all their Tesla immerion heaters for £5, usually £25-35.
If yours was the same make I would try and get a different make ie Backer

 

[Keepinghouse]

Hi Davey thanks for the response. Ive had a few teslas and the other was an ideal. I did think the ideal was better made but it too only lasted 2 months. How were your immersions failing??

 

[Keepinghouse]

Are you in a hard water area?

yes but we have a water treatment/softener which works very well. there is zero limescale on the failed immersions

 

[Keepinghouse]

Is something causing the water level to drop?

i had thought about this..do you mean as if to say that the element is heating without any water? I would think the element would burn up rather than the thermostat/tube as that merely detects heat

 

[Johntheo5]

i had thought about this..do you mean as if to say that the element is heating without any water? I would think the element would burn up rather than the thermostat/tube as that merely detects heat

You're correct, the only way I can see that pocket/tube failing is either mechanically, maybe (but very unlikely), fouling on something inside the cylinder or very acidic water corroding it but most unlikely in a matter of a few months. You might hold on to this one when you remove it and take a few photos.

 

[ericmark]

i had thought about this..do you mean as if to say that the element is heating without any water? I would think the element would burn up rather than the thermostat/tube as that merely detects heat

Sorry, I was assuming it was the element, as there is no reason why the thermostat pocket should ever fail. It is just a bit of pipe brazed into the plate, how can that be damaged?

 

[Keepinghouse]

Sorry, I was assuming it was the element, as there is no reason why the thermostat pocket should ever fail. It is just a bit of pipe brazed into the plate, how can that be damaged? View attachment 409261

yep thats exactly it. if i bypass the wiring on the thermostat it will heat as intended. when i pull the thermostat out of the tube theres a little bit of water in it

 

[Keepinghouse]

it fails the exact same way every time.

 

[Johntheo5]

Sorry, I was assuming it was the element, as there is no reason why the thermostat pocket should ever fail. It is just a bit of pipe brazed into the plate, how can that be damaged? View attachment 409261

I've seen postings where incoloy immersions but with copper pockets do fail (leaking pocket) in less than 6 months, when used in stainless cylinders, its suggested to ensure that the pocket also is incoloy, apparently some are not.

 

[Harry Bloomfield]

My immersion and its stat, are 40+ years old. It is rarely used, there for boiler failure - we normally heat via gas, but I have made recent good use of it, during the free Octopus power sessions. A few months ago, I replaced the stat, not because of any failure, but to upgrade it, to an overheat cut-out version.

In the OP's stat pocket failure, rather than a leak due to failure of the pocket, I would be suspecting moisture getting in via the open top from some source.