Warning - Check your immersion heater

thenudeone

A salient warning for anyone considering using solar PV for an immersion heater -

Check that the thermostat safety cut out works, otherwise the water in the feeder cistern could become so hot that the cistern melts, with devastating consequences:
http://www.dailymail.co.uk/news/article-506604/Water-tank-fault-scalded-baby-girl-death-known-unreliable.html

The warnings are equally valid whether solar PV is used or not.

Another example of the same problem is shown in the second photo on this page (which is a solar-PV powered immersion heater)
http://www.g4hjw.metahusky.net/solarpv.html

Fred_Bear_2

This was a tragedy.

Quoting from the article:
"No thermostat in the United Kingdom had failed for 50 years, and the law may change as a result of this inquest."
So perhaps people should not panic too much.


Also from the article:
"Hours before the tragedy, they found scalding hot water coming out of the cold tap in their bathroom but did not know what to do about it."
The lesson here must be that if you find boiling water coming out of the cold tap then it is a good idea to switch off the immersion heater and call a plumber.

celerity

Without wishing to in any way imply this isn't a horrible story, the cynic in me does imagine the glee of the Daily Mail reporter covering it. Claiming millions of babies are at risk of fatal scalding is quintessential Mail. The only thing that could have made it more perfect would have been if the fault was traced to an illegal immigrant plumber...

Anyway rant over, and obviously this story has public interest - I just hate the Mail!

/\dam

rogerblack

Fred_Bear wrote: »

This was a tragedy.

Quoting from the article:
"No thermostat in the United Kingdom had failed for 50 years, and the law may change as a result of this inquest."
So perhaps people should not panic too much.

This is basically !!!!!!!!.
There is no central reporting of this - it'd only get noticed if it did actually kill someone, and even then may not make more than local news if it's not someone photogenic, and there is not the possibility of the landlord being at fault.

What happened required a specific unlikely chain of events.
The thermostat failing closed.
Insulated plastic cold water tank. (an uninsulated one won't get hot enough)
The above to be made of a thin enough gauge of plastic, and unsupported, so that it can sag and burst or spill.
The householder not to take action on the banging noises due to the boiling, or the hot cold water.
The element not to fail when partially exposed in steam.
The thermostat being on a non-timed circuit.
The pipework being arranged in such a manner to allow this to occur.

EricMears

I believe that someone mentioned in these forum pages a few days ago that all future immersion heaters will incorporate an additional overheat device in addition to the normal thermostat.

However, that's unlikely to mean that all the millions of existing immersion heaters will have to be upgraded.

It's also not clear at what temperature the new devices would have to operate. Limiting tank temperatures to (say) 50 deg C would probably prevent such an accident - but it would also prevent more sophisticated systems from woking properly. e.g. my Heat Bank is perfectly safe to operate at around 90deg C because hot water from it is supplied via a thermostatic mixer valve. Limiting such a system to 50 deg C would virtually halve the amount of useful hot water the system could supply. But, a thermal device designed to cut out at 90 deg C might have a 10 deg margin of error hence allowing water to boil under very rare circumstances.

An immediate change in the law following any unusual case - however tragic - almost always throws up more problems than it solves.

Fred_Bear_2

rogerblack wrote: »

This is basically !!!!!!!!.
There is no central reporting of this - it'd only get noticed if it did actually kill someone, and even then may not make more than local news if it's not someone photogenic, and there is not the possibility of the landlord being at fault.

Hi Roger, surely you are not suggesting the Daily Mail would try to mislead its readers are you? If so then maybe Climate Change is true after all.

Martyn1981

Fred_Bear wrote: »

Hi Roger, surely you are not suggesting the Daily Mail would try to mislead its readers are you? If so then maybe Climate Change is true after all.

Nah! Climate change / AGW aren't real, the problem is all those illegal immigrants stealing our good ole British air, and breathing out CO2.

Mart.

Fred_Bear_2

Hi Mart, that's wot I thought!

Fred

Kernel_Sanders

So, there were two things amiss here:
1. The water was scaldingly hot.
2. It was coming from the cold tap as well.
Either of these should have prompted someone to simply pull the cord or turn the switch off. But both of them ? Surely even the most technically challenged person would have realized something was seriously wrong.

The article doesn't actually state if the thermostat failed, or if it simply didn't cut out at a low enough temperature. It also states that the coroner said ""No thermostat in the United Kingdom had failed for 50 years". What nonsense, how could he possibly know that? As reported in another thread, mine failed in the 1980s.

HappyMJ

Kernel_Sanders wrote: »

So, there were two things amiss here:
1. The water was scaldingly hot.
2. It was coming from the cold tap as well.
Either of these should have prompted someone to simply pull the cord or turn the switch off. But both of them ? Surely even the most technically challenged person would have realized something was seriously wrong.

The article doesn't actually state if the thermostat failed, or if it simply didn't cut out at a low enough temperature. It also states that the coroner said ""No thermostat in the United Kingdom had failed for 50 years". What nonsense, how could he possibly know that? As reported in another thread, mine failed in the 1980s.

The coroner also references this case http://www.guardian.co.uk/uk/2003/jul/02/2 http://news.bbc.co.uk/1/hi/england/cornwall/3035606.stm from 2002. That's only 10 years ago.

Kernel_Sanders

HappyMJ wrote: »

The coroner also references this case http://www.guardian.co.uk/uk/2003/jul/02/2

In that article it states a fault in its immersion heater had allowed the cold water tank to fill with scalding water and that The hot water flowed into the cold water tank in the loft until eventually that too was filled with boiling water.
The author cannot know how the system works because (she?) doesn't realise that it was just the the heat that migrated from the cylinder up through the gate valve.