Immersion thermal cut off

.G.

Have an immersion,it was only replaced in the last year or so but now its tripping its thermal cut out regularly. The stat appears to be working and is set to 60c so I'm wondering is a faulty stat the likely cause, faulty cut out or can it be something else?

meercat

Your domestic heating system(oil or gas) can also trip this if it is set too high

tomdempsey200

ya
other heat sources is a culprit sometimes.......back boilers too

.G.

No other heating sources have been on as far as I'm aware but I'll check. This is recent thing though and the immersion had been working fine throughout the winter when gas heating would have been in use.

Bruthal

If central heating has not been on, then likely either the immersion stat is not cutting out early enough, or faulty overheat stat. Measuring the water temp can show the immersion stat cut off level.

.G.

I changed the stat,its still cutting out so must be the overheat. Funnily the stat,no matter which way you turned it,gave continuity. The new one also did this,do they no longer close on turning the dial anymore?

tomdempsey200

superg wrote: »

I changed the stat,its still cutting out so must be the overheat. Funnily the stat,no matter which way you turned it,gave continuity. The new one also did this,do they no longer close on turning the dial anymore?

the water was prob cold ?

if the tank is heated they'll make and break

Bruthal

superg wrote: »

I changed the stat,its still cutting out so must be the overheat. Funnily the stat,no matter which way you turned it,gave continuity. The new one also did this,do they no longer close on turning the dial anymore?

Yea the stat won't open with cold water as the lowest set point is probably well above room temperature.

.G.

Thanks chaps. It must be the Thermal cut off which can't be replaced so probably new immersion.I'm leaving it to a plumber.

Robbie.G

superg wrote: »

Thanks chaps. It must be the Thermal cut off which can't be replaced so probably new immersion.I'm leaving it to a plumber.

Why can't it be replaced.What make of immersion is it because I haven't come across one that can't be changed

.G.

no idea but it didn't look removable to me.How do they come out? It was the first immersion I'd seen with a thermal cut out on it.

Edit:-reading this thread,even if it can come out I'm still leaving it,there can be many causes to this problem,the plumber can sort it.

meercat

you could possibly remove it from the circuit and fit a thermostat with inbuilt overheat switch

http://viewitem.eim.ebay.pt/7-11-and-18-IMMERSION-HEATER-THERMOSTAT-RESET-AND-OVERHEAT-GENUINE-COTHERM/170732477901/item

available in your local wholesalers

maxamillius

Can you not just pull the thermostat out from the element sleeve?replace the thermostat you can buy them in most places,the thermal cutout is part of the stat?
Surely the whole element does not have to be replaced?!

Bruthal

maxamillius wrote: »

Can you not just pull the thermostat out from the element sleeve?replace the thermostat you can buy them in most places,the thermal cutout is part of the stat?
Surely the whole element does not have to be replaced?!

Either the overheat stat is faulty, or the element is actually overheating.

Might be badly limescaled if the cutout is working properly and cutting out due to high temperature. Water is then not keeping the element cool enough during operation. If that was the case, replacing the stat, and it will just do the same thing.

A scaled up element can overheat at the top long before the water gets hot enough to operate the temperature stat. An air pocket trapped at the top of the element would also cause it, although that would be unusual.

Meercat`s combined overheat and temperature stat looks a good idea.

.G.

Bruthal wrote: »

Either the overheat stat is faulty, or the element is actually overheating.

Might be badly limescaled if the cutout is working properly and cutting out due to high temperature. Water is then not keeping the element cool enough during operation. If that was the case, replacing the stat, and it will just do the same thing.

A scaled up element can overheat at the top long before the water gets hot enough to operate the temperature stat. An air pocket trapped at the top of the element would also cause it, although that would be unusual.

Meercat`s combined overheat and temperature stat looks a good idea.

Yeah there seems to be numerous reasons why it can happen so I've passed it along already.

@Maxamillius, its not the thermostat causing the problem,it appears to be the overheat cut off which on this immersion was completely seperate to the thermostat. I've worked on immersions so infrequently it was the first time I'd even seen an overheat cut off on one!

Thanks to meercat if it comes up again I know I can get one of those all in one Thermostats.

maxamillius

Ah right,I've only ever used the all in one types!!