boiler thermostat playing up

[joko]

when i put the immersion heater on, SOMETIMES the water gets hot, mostly it just gets to warm, no matter how long i leave it on for - hours and hours even.

I thought the thermostat was broken but how come it still makes the water warm and sometimes gets properly hot?

any idea of what could be causing this and what can i do about it?

i have the sort of timing device that has a ring of 15minute interval buttons and you move them inwards depending on how much hot water you want

many thanks

[markja]

it may be the thermostat on the imersion or the element in it.either way these are cheap and easy to replace. make sure the person doing it knows what they're doing 'cos there are some pitfalls.

[ACB312]

I largely agree with Markja - but you mentioned a timer. The electrical load of an immersion heater (about 3KW) is possibly a bit high for basic plug in type timers - so you may have a problem with the timer's contacts being slightly fried. Normally an element is go or no-go so this points to the thermostat being at fault. Anyway, it is not too expensive to replace the heater/thermostat but I would check the rating of your timer.

[joko]

cheers guys.

the timer is fitted not a plug in one.

where is the thermostat? can i look at it and see if its broken or will it need to be dismantled?

[markja]

on the immersion there is a lump with wires going in it.don't touch it yourself, by your reply above, you don't have the knowledge to do the job safely. we are talking mains electric here! that's one of the pitfalls i was on about. another is that the tank is full of water which could make a lot of mess if the job is done wrongly.

the thermostat is often inside the heating element.both under that lump.

[joko]

oh, i wouldn't try anything, just want to be able to tell what the prob is.

are there any fuses or anything that may need changing?

or anything i can safely try before calling someone in?