Immersion Heater Box overheating

Tabitha_T

Morning all

I noticed a fishy smell in my bathroom this morning, tracked it down to the airing cupboard and the white plastic box which houses the immersion heater switch is very hot, I would say way too hot. I use my immersion a lot for heating water but obviously I have now turned it off. Does anybody have any idea what the root cause of this problem could be? I'd be grateful for any advice. I do know a heating engineer who does mates rates but he's on holiday.....:(

macman

Faulty switch, or loose connection causing arcing possibly. You don't need a heating engineer, you need a electrician if the fault is in the switch. The fishy smell is due to melting/burning plastic, so turn off the immersion heater circuit until it's fixed.

har0ld

I would agree with macman although what might be happening is that the immersion itself is going and somehow the switch is now dealing with a higher current than it is rated for, this could be a sign that something is not right with the earthing or fusing/trips for your immersion..?.. either way you need an electrician and if the immersion is going, possibly a plumber as well.

Enterprise_1701C

I would agree with har0ld - last time we had the same problem I just thought it was because it was very warm in the airing cupboard, but that night I was woken by roaring sounds from the hot water tank which was on the verge of boiling! Cue a quick rush around turning on all the hot water taps and turning off the immersion and a trip down B&Q to replace the immersion!!

karl-123

new isolating switch,
new side entry or top entry imersion, heater with overheat cut off,
set to lowest hot water temperature comfortable with.........

Tabitha_T

Thanks to all for your help and suggestions, have tracked down an electrician who is coming on Thursday. Will let you know the outcome! Cheers, Tabs

ListysDad

Tabitha. Just be VERY careful. If your cold water storage tank in the loft is located over anyone sleeping/playing make sure they are never under it till it's sorted. IF (and it's a reasonable if) it is the thermostat that has gone then water may be boiling over into the tank in the loft. As these are not designed to take this temp they can collapse. Two people have died from being scalded in this way so when sparky arrives get them to check to see if you have a thermostat with a safety cutout fitted to ensure this can never happen to you.

Canucklehead

ListysDad wrote: »

Tabitha. Just be VERY careful. If your cold water storage tank in the loft is located over anyone sleeping/playing make sure they are never under it till it's sorted. IF (and it's a reasonable if) it is the thermostat that has gone then water may be boiling over into the tank in the loft. As these are not designed to take this temp they can collapse. Two people have died from being scalded in this way so when sparky arrives get them to check to see if you have a thermostat with a safety cutout fitted to ensure this can never happen to you.

Not true.

They are tested to withstand boiling water for 500 hours without collapsing.

It's the INSTALLATION that is at fault. The CWSC MUST be sited on a suitable flat and level base wider than the CWSC.

A Victorian 4 panel door is not suitable! Nor is balancing a plastic one on top of the original galvanised one. More here.


GSR.

Canucklehead

andrew-b wrote: »

It's a very subtle distinction but isn't it actually they are tested to withstand boiling water for 500 hours without collapsing but when "fully supported across the base area" of the water tank. Which implies to me that it's ok for a plastic cistern to deform when inadequately supported and filled with boiling water.

With a safety cut-out on the immersion heater those particular deaths might well have been avoided though. Without doubt it's better to have a tank of cold water fall on you than one of boiling water.

For the record this document describes those cases : http://www.ciphe.org.uk/Global/Databyte/Cistern%20Installation.pdf (sure there is some irony in me quoting ciphe documents!!).

I'd feel inclined if i were the OP to replace the immersion heater if it doesn't have a safety cut-out especially as all is not right at the moment. Perhaps overkill and not money saving though.

Could have saved yourself the agony of the irony as I've already linked to that Databyte.

Also need to consider whether the float valve used in the install has been tested to 500 hours.

GSR