Posted By holmezy
I've read, with interest, the points and comments made on this thread and have decided to jump in with my tuppence worth.
Firstly, the boiler didnt explode. The hot water in this case was generated via an immersion heater in a calorifier, (or hot water cylinder). The thermostat on the immersion heater developed a fault which caused the water in the calorifier to keep boiling which then produced steam, initially and then a volume of 100+ degrees water to be forced up the expansion pipe and into the cold water header tank. As the hot water is expelled, it is replaced by water from the header tank. There may even be ingress of fresh cold water to the system via the ball valve to replace the water lost in steam. This cycle then continues, due to the thermostat being continually "on" until the boiling water and potetially superheated steam in the header tank expands so much that the overflow on the header tank cannot remove the water quicker than it is being introduced to the system and hence the tank will then overflow, and depending on the design (plastic) age and condition of the tank, may cause the tank to distort or "melt". The end result is boiling water escaping from the header tank and soaking the ceiling below and eventually breaking through.
Secondly, this has happened many times before, not only in council homes but private homes. (I know from my previous life as a plumber) and usually the water drips through the bathroom ceiling during the night and harms no one. As it was at night and in the bathroom, no one got hurt.
Unfortunately, on this occasion, and a previous occasion involving a young woman, the water tank was positioned over a bedroom. The baby was, (I think) in a cot and as such couldn't escape, although I would think that a sudden deluge of boiling water would render infant either in shock or death, both of which would be rapid.
It is an extremely unfortunate accident, with extreme consequencies, but is it the HSE's fault? I don't think so. Should they have warned the council(s) or raised their concerns? possibly. Would or did the councils take any action on checking the thermostats out in the 1000's of properties? Probably not. You can go and check a thermostat every day of the year, but when it fails, it fails. Its a bit like a light bulb, it either works or doesnt. Nowadays, most, if not all thermostats should fail to safety (???), but there must be thousands out in the homes of council tenants and private tenants that "may" fail to danger, ie "on", I know my kettle boiled dry when it failed.
My point after all this, is why do we have to look for someone to blame? By all means establish the cause. We could potentially blame designers, builders, plumbers etc for siting a header tank over a bedroom, we could blame the thermostat manufacturers, where do we stop? The press make a living out of blaming people, surely we should be better than them at least?
So we now all know about the potentially low liklihood that we all may have a potentially rogue thermostat on a potentially rogue immersion heater that may fail to danger with potentially fatal consequencies. As people keep telling us, do the risk assessment! Are we all going to go home a check the thermostat tonight, the position of the header tanker, position of the beds etc. I think not. And if you are going to check it, what and how are you going to check? And how often?
(Steps down of soap box and retires quietly to the corner of the room, fully expecting to be lambasted by someone shortly......)
Thanks for listening though..
Holmezy
Sod the diet, tonight I'm having a pint or two of the most calorie laden ale I can find.