Potential immersion heater issue (just been on BBC News)...

mountainchrisriver

Not sure if this has been posted, or if there is much you can do about it really... but worth giving folks the heads up as it obviously has fairly drastic (if thankfully rare) consequences... Child was killed when thermostat failed to shut down immersion heater, consequently the boiling hot water overflowed into the plastic cold water tank in the loft and then eventually this melted(?) releasing the hot water through the ceiling onto the childs cot...

http://news.bbc.co.uk/1/hi/england/somerset/7175037.stm

Suppose one way to help prevent this is to turn the immersion heater off if not required... I used to have a solid fuel stove with a back boiler that would often boil the water with similar issues of sending hot water into the cold water tank in the loft...

Mods feel free to move this if you think its in the wrong place or would be better suited elsewhere?

BobProperty

This case was highlighted by me when it first happened. The inquest started today and, unlike some reports and comments, it has happened at least once before with fatal results. http://www.trustedtradesmen.com/forum/forum_posts.asp?TID=9940

The situation arises with old immersion heaters which do not have "overheat" thermostatic cut-outs. If the thermostat fails in a certain way it leaves the power running through the circuit instead of cutting it off. The immersion heater is therefore "on" all the time and the user is putting, say, 3kw into the hot water cylinder continuously. This heats the water and causes it to circulate (hot rising) with the water in the header tank. Eventually all the water gets to near boiling point and the plastic header tank (possibly helped by any slight defect or installation imperfection) deforms or splits under the heat with the consequence of the contents coming through the ceiling if that was where the tank was.

All the talk about people not having ladders or not inspecting the houses properly is missing the point about the defect. You would not know of the defect until you ran the immersion heater for several hours. In this case the occupiers had only just moved in, In the earlier case, IIRC, they had been there for a few months and had complained about water coming through the ceiling on previous occasions but nothing had been done or no one had realised what the problem was.

maninthestreet

BobProperty wrote: »

This case was highlighted by me when it first happened. The inquest started today and, unlike some reports and comments, it has happened at least once before with fatal results. http://www.trustedtradesmen.com/forum/forum_posts.asp?TID=9940

The situation arises with old immersion heaters which do not have "overheat" thermostatic cut-outs. If the thermostat fails in a certain way it leaves the power running through the circuit instead of cutting it off. The immersion heater is therefore "on" all the time and the user is putting, say, 3kw into the hot water cylinder continuously. This heats the water and causes it to circulate (hot rising) with the water in the header tank. Eventually all the water gets to near boiling point and the plastic header tank (possibly helped by any slight defect or installation imperfection) deforms or splits under the heat with the consequence of the contents coming through the ceiling if that was where the tank was.

All the talk about people not having ladders or not inspecting the houses properly is missing the point about the defect. You would not know of the defect until you ran the immersion heater for several hours. In this case the occupiers had only just moved in, In the earlier case, IIRC, they had been there for a few months and had complained about water coming through the ceiling on previous occasions but nothing had been done or no one had realised what the problem was.

How do I tell if the immerson heater I have is the old type or not?

tomstickland

What a horrific story.

The age of the parents ranges from 21 to 27 in the various BBC reports.

mountainchrisriver

tomstickland wrote: »

What a horrific story.

Yep and it was their first night in the property... how would they have ever known...

EliteHeat

maninthestreet wrote: »

How do I tell if the immerson heater I have is the old type or not?

Take the cover off and look for a small reset button. If you don't have one then you have the old style thermostat.

Unless your immersion heater is less than a few years old this will almost certainly be the case.

roddydogs

I dont get how this happened-the cold tank is full of cold water-the boiling water is discharged into this, and when it reaches the overflow, it goes out.
How does the whole tank become boiling?

djheath

roddydogs wrote: »

I dont get how this happened-the cold tank is full of cold water-the boiling water is discharged into this, and when it reaches the overflow, it goes out.
How does the whole tank become boiling?

The hot water coming out out of the immersion tank is venting to the cold water tank in the loft. The immersion heater is then filled automatically with cold water from the cold water tank to take up the space of the vented hot water, so the cold water tank never gets full, the water that is displaced from the immersion, is just brought back into the immersion. After a time the cold water tank is full of vented hot water and therefore only hot water is being brought back into the immersion to be heated. Hence, boiling water is just being pumped around the system.

MRSTITTLEMOUSE

years back when we lived in a rented flat,we had a similar problem.I went up stairs and found the thermostat had had gone haywire on the immersion.The cupboard it was in, the doors had buckled out and the paint was peeling off,like it had had a hot air stripper applied to it.There was also scalding water dripping out halfway across the ceiling,you could smell scorching.Luckily although this was my childs bedroom,it was through the day and they were at school.I dread to think of this poor child after seeing what this was like for myself.

nick74

Its quite cheap and easy to change the thermostat on an immersion heater to the new type. Basically turn the power off, take the top cover off the immersion heater, undo the 2 wires to the thermostat, slide the thermostat out, slide a new one in, reconnect the 2 wires and put the cover back on.

Canucklehead

Hi


Very good post here...http://www.diynot.com/forums/viewtopic.php?t=118483

Corgi Guy.