Immersion heater life

[Brian]

Fitted an immersion heater for a friend about a year ago, replacing one which had failed. It is a 3KW, 11 inch one which goes in across the bottom of the tank. It is on economy 7. There is also another heater near the top of the tank for topping up the hot water. Anyway, friend called last week to say that the overnight hot water was not working, so I popped round to see. Fuse had gone, so I checked the element - open circuit. So I had to drain the complete tank to remove it. I have never seen the like before, the whole of the tube containing the element had split along its length, and I mean the whole length. I did buy the original from Wickes. Needless to say they don't want to know. What is the average life of an immersion heater? We are not in a particularly hard water area, the top heater has been there for years, with no problem, and the old one I took out had no physical damage either.

[Palindrome]

This is my suggestion as an explanation:

The circuit isn't protected by a leakage current trip.

A small pinhole opened near the neutral end of the element. This would have tripped a leakage breaker - but not blown a fuse.

Water worked its way along inside the tube.

The element wire corroded and went open circuit - creating an arc which turned the water inside the tube and near the arc into high pressure steam.

The expanding high pressure steam split the tube open from end to end.

The fuse blew.

Suggestion ends..

Of course forget I wrote that lot if there is a leakage breaker protecting the circuit..

Otherwise, you may be able to detect the pinhole..

It may not be a pinhole but a deep scratch* or other site for crevice corrosion, exacerbated by the thermal cycling. But careful examination should find it.

• Which may be tiny and nowhere near the split.

The element may have come with a one or two year warranty - but it would have been invalidated if it had suffered a deep scratch during installation.

If you can find a pinhole, you can argue that it was a defect in manufacture and demand a replacement. If it was a scratch, then proving it was there when purchased is going to be a bit difficult..

Whether it is worth arguing, I leave to you...

-- Sue

[Brian]

installation.

The explanation is more or less what I had assumed, but there is no scratch. Some sort of leak which allowed water in is obvious, but not seen. It is also possible that the seam weld along the tube was not done as well as it might, and since this is what has split open, the original fault will be hidden.

[Nobby]

I have an immersion heater, not in regular use, recently and in summers only, that is thirty years or so old - in a hard water area.

[Brian]

The one we have in our house is used daily, and is 10 years old at least.

[cj]

Hi Brian Agree with all said but in my career have only seen 3 similar failures first in a cleaning tank where cleaner ate through the copper after 2years of service,second when a stat failed after 6yrs or so and caused boiling and third (funnily enough) in a similar split tank fitted with a replacement from (you guessed it) . Turns out the last was a cheap foreign copy of a 'Ring' heater which failed when the rolled seam split as yours appears to have. IMO immersion heater last at least 3-5yrs in constant use and most a lot longer like me I think you got sold a pup.

BTB No I don't buy from 'wikes' anymore and No I didn't get a refund ,not even a sorry.

CJ

[GTS]

When I last repplaced my immersion, I got it from Wickes - and there was a choice of 2 types - a cheap one, and a 'long life' one (which was still pretty cheap). I got the long-life version and it been going for 7 years now - Economy 7 so used every day. GTS

[Brian]

Yes there are two types, the normal copper one, as it is labelled, and the one with a special coating for very hard water areas, which we are not. No doubt the more expensive one (40% more) might well last longer.