Help: Immersion heater and economy 7 circuit

12 Nov 2005
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United Kingdom
The immersion heater in my house has stopped working and I called in a plumber who simply replaces the immersion element and it is still not working. (despite assurance that he has 'tested' it).

The hot water tank has a single immersion element at the bottom which is connected to a switch on the wall, which from some research shows that it is eco-7 powered.

I have carried out the following test:
(a) Press the booast button.
(b) Use circuit tester & a neon scredriver and found that the circuit has no current.

The immersion heater controller is connected into two consumer unit like boxes. The first boxes is a RCD/MCB unit and has a MCB labelled "Water Heater." The controller also has a connection into a fused box which labelled all the fuses as "storage heater".

Is it likely that under such configuration, that the water tank switch is only powered by the economy 7 circuit and hence pressing boast would not have effect anyway and that one of the fuses labelled as 'storage heater' is actually a fuse for the immersion element & has gone ?

Thank you veru much in advance for your help...
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Donn't know but if it were me I'd be doing some continuity testing once having locked off the supply so it was safe.
one of the fuses labelled as 'storage heater' is actually a fuse for the immersion element & has gone

Un'gone' the fuse for starters :!:

Remember economy seven doesnt come on till late at night

After that you need a sparky round. With part P now in force there wont be much more you can do yourself anyway
Yap..tried "ungone" the fuse but it did not help (cannot even be sure that one of those lableed as storage heaters fuses is actually an immersion heater fuse). The electrician who installed it was just to 'clever' to have left everything unlabled...

Is economy 7 a completely different circuit and hence the switch at immesion heater (and the storage heater consuemr unit) is only powered by the eco 7 circuit ? (And hence pressing booast would not help anyway as it is not connected to the circuit).

How eco 7 and normal supply works ? Do both supply get fed into the consumer unit and one of them is activated at a time?

many thanks !
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Don't know it wasn't covered on my part p course.

I had a sparky wire up a shower once and after he'd been the economy 7 came on in the day isntead of at night. He had no idea why.

I suppose there must be someone who understands these mysteries.
Hi Paul,

Perhaps it is because the "Eco 7" hour has arrived !

Not all eco 7 runs from midnight to 6. e.g. (Manweb region in Wales by Scottish Power) one get off peak electricity between 2 and 5pm in the afternoon and between 10pm and 9am overnight.
Do both supply get fed into the consumer unit and one of them is activated at a time?
Best to post that in electrics!
If it were wired for eco 7 I would expect to see an extra meter or some sort of time control for eco7 specific appliances
Often just a separate display on the meter. The timer isn't in the meter but back up the line - the instruction to the meter to change counter is carried on the mains. (They've been playing with methods to read meters on the wires since the 80's to my knowledge).

You're up late, Slug!
Thanks guys.

Found out in the end. eco7 controller fault, despite the boast LED light up, it is delivering no power to the Immersion element...

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