Right we have a dual element water heater/storage tank and are on ecconomy 7 tariff.

There are two elements on the tank, the first is at the top of the tank and is connected to a timer (set to come on between 12-7)

The lower element is connected to a switch which is never turned on.

The problem is by the evening the water is barely even luke warm.

Is this wired correctly? For a while we changed the timings so that it comes on in the evening to boost the water temperature. However im wondering whether it would be more sensible to wire the timer to the lower heater and heat the whole tank over night and hopefully it will stay hot all day?

 

I've got the similar setup at my house and had a problem like this.

Turned out the timed (E7) immersion element was dead. A sparky replaced the element (£6 for the part, £10 for his time IIRC) and I never had to use the manual switch element again.

 

Which one is the E7 element on yours? the top or bottom element?

 

Normaly the lower immersion is the E7 cheap rate one this gives a greater volume of hot water at a cheap rate.
The top one is a booster day rate for "top up" if water goes warm/cold.
We install and maintain them they can be very good if set up correctly.

 

I think that explains my problem them, as the top one only comes on at night and the bottom one never comes on at all hence only the highest water is heated at night, thus loses temperature to lower water through the day.

Had it all re-wired last year, don't think it was set-up correctly from new and think the electrician made any even worse job of it.