No power to immersion heater

Harry Worth · Jul 29, 2011

Mate asked me to look at his immersion heater that had stopped working. The tank has two elements - labelled 'On Peak' and 'Off peak'. It is the off peak one which has failed. No breakers tripped but the neon on one of the switches (off peak) is out. I've measured around the circuit - no power anywhere so I took the front off the CU to check there. There are two circuits - one supplying the immersion - no power on the input to that circuit so no power to the storage heaters either. The meter is outside his flat - How does the economy meter work. It seems as if there are two supplies entering the CU - One of which is dead. Is it possible for this to be down to a fault with the meter or am I woofing up completely the wrong bush?

truckster · Jul 29, 2011

The off peak supply is only live between midnight and 7 am or something like that. Go back at 1 AM and check then.

Harry Worth · Jul 29, 2011

Yes - I did wonder if that was how they worked but my mate swears blind that the neon was always on before.

Octopus · Jul 29, 2011

My guess is that the element which is "off peak" (and probably positioned lower in the tank) has failed and as above you'll need to go back during the night to check it out. If the isolation switch has a neon, ask the client if its on during the night.

Have fun!

Deleted member 9648 · Jul 29, 2011

Do a continuity test on the circuit at the CU..(isolated)...with the immersion switched on....if all is good you will get a reading of around 18 ohms through the element,in which case if energised it will work,so look at supply problems..(this is better than a night visit in my book!)....if not work back from the element/stat..(most likely culprits).