Immersion heater Please Help!!!!

Please could you advise.

My girlfriend has been living in her flat for 4 months, there is no gas to the Flats and the water is heated an immersion heater.

The unit has 2 elements on the side one below the other, it has 2 power switches on the outside of the cupboard, the top one has a light on it and is a sort of a rocker switch, the bottom one is a normal switch, I can see no external thermostats, the cylinder is large and coated in a green foam, and has a black plastic lid on the top and looks very good condition, the flats are only 10 years old.

We have normally left both the power switches turned on and not touched them, and the system has been very quiet and worked well.

Last night I could here a noise like a kettle boiling and this was going on for some time, I left this but the noise continued, so I turned the bottom switch off, the noise stopped strait away.

I left this of all night and the in the morning switched this bottom switch back on; strait away it started the kettle noise again. As though the water was at temperature

Please could you advise me on this, the temperature has not changed much in my area over the last day, to suddenly do this, we have not touched any of the setting or the switches. please could you explain this system and how the twin elements work, and the best way to go about diagnosing this, I have meters and all those sort of things.

Thank you

Darren

it may sound daft but do you get the same flow (as previous) from the hot tap?

I am wondering if the tank in the loft is full?

you wont see the stat becuse it is under the black lid, but the bottom element seems to work since it makes noise, and not when turned off.

It may be the top element has gone , and bottom one on its way, but check loft tank first

I did say that this is in a FLAT? no other tanks I can See?

but the top one must be working? as it stayed almost boiling all night, what tests can I do?

probably due to scale on the element.

Are you on economy 7 if so the bottom heater is for overnight heating and the top one is just used as a booster in case you run out of hot water during the day

ok yes I think is ecco7 how does it know to power up the corect element overnight? does 1 element go to seperate meter? how does this work?
why do you think this has only just gone like this, is ther a test I can do ?

thanks guys for the responce

Test for what is working?

You cant test it cos its noisy, you can take it out and clean all the scale off but you may as well replace it then

Yes its probably wired direct to the eco seven consumer unit.

I agree with taydo, it's probably scaled up. You will need to drain the tank to change it, and while you have it drained, change BOTH heaters. They are not expensive, but it's really irritating when they stop working unannounced, and the scaling is not far away from the end of life.

thank you for the advise

When you say the cylinder is large and has a black lid.I assume the lid is also large. Is this one of those cylinders that has a built in cold water tank (with a ball valve) mounted on top. Have you lifted the lid to see under.This would explain why there is no other tank.

Is the water getting very hot? If so it could well be the thermostat in the heater unit that has packed up. You can leave the power on to your immersion heater all the time, the temperature is regulated by the setting on the 'stat.

Switch off at the wall, take off the cover and you will see a semi triangular black box looks like



The water temperature is adjusted by turning the screw in the centre. You chould be able to hear a click if you turn the screw from one end to the other however the thermostat may have gone short circuit. You can replace it by removing the wires and pulling it out.[/img]