Immersion heater - what electrical circuit?

FBThree

Sorry if this is the wrong forum!
Can anyone tell me what circuit the immersion heater should be attached to? Mine was apparently attached to the 30 amp cooker circuit in my house. Worked well for quite a while but when it blew, the plumber said it should be wired to the 15 amp and wouldn't change it until it was re-wired. Now it's linked to a 15 amp circuit it hardly gets warm after 3 hrs of heating.
If it makes any difference I think it's a tank that is meant to heat up a sink-full of water or a full bath load depending on some setting or other than I have no idea where it would be.

penrhyn

Sounds as if the immersion heater is faulty, why did it blow in the first place?
Immersion heaters are around 3 kw so should be run off a 13/15 amp spur.

Cardew

Immersion heaters are typically 3kW so a separate 15 amp circuit will suffice.

Some have a dual tank system where you can heat up sufficient for, as you say, a sink full of water.

It is obviously a bad idea to have it connected to your cooker circuit as with both on you can exceed 30 amps.

When you say "it blew" what to you mean? Having it connected to the cooker circuit, whilst obviously bad practice, will not cause you immersion heater 'to blow'; just the circuit breaker to trip because it is overloaded.

Wiring it to 15 amp or 30 amp will make absolutely no difference to how fast it heats up. They are either on or off; although a thermostat controls how hot the water gets.

You can easily see if it is connected or working by watching your meter. When the heater is switched on you will see the dial spin around fast.

If your Immersion heater is not faulty I suspect you have got your settings wrong.

FBThree

Thanks folks. That has cleared it up in my mind. The maintenance guy ended up putting it on it's own 15 amp circuit, replacing the immersion heater bit. Resetting the timer clock properly helped too. I've had the immersion element "go" or "blow" before, which I think is due to a limescale build-up in our area. I just thought it was strange that its worked fine for ages, when it must have been on the 30amp, but as Cardew has pointed out wouldn't have been a good idea anyway as the cooker and heater could have exceeded the 30 amp - arrgh, never knew that was wrong! I guess this time I just got a plumber who knew what he was doing with electric.

I must check my house insurance against fire. And smoke alarms come to that!