Advice appreciated: E7 tank wired to an E10 meter

We have e10 heating and the bottom element turns on automatically during off peak hours. Try running the hot tap to see if you have hot water.

The top element will cost a fortune so avoid using that.

Simon72 wrote: »

The hot water tank has two heating elements, top and bottom, and from what understand one was the E7 off-peak, the other some sort of day boost.

Yes, often the tank will be fitted with two heaters, the lower one will heat the whole tank, the top one just heats the water nearest the top. Sometimes a single dual-element heater is fitted near the top of the tank which combines both functions - so there is no hard and fast rule about the number of visible heaters and what is actualy inside the tank. The 'boost' element would normally only be used to add some heat during the day if you have run out of hot water.

Simon72 wrote: »

The house is now on E10 though and it looks like the lower thermostat is no longer wired to a live circuit. If I turn the top one on I can hear it starting to heat up but correct me if I’m wrong, I don’t want to be using that? There is also no timer of any sort.

I'd want to understand more about why the lower heater (I assume you mean that, not 'thermostat'?) is not connected. Immersion heater elements can corrode allowing water to come into contact with the live heating wire - if this happens the earth leakage protection for the circuit (or whole house) should 'trip'. If the water heating was not in use and this has happened in your case then someone may just have isolated the supply to the immersion heater to 'fix' the problem. Replacing or removing a faulty heater is a more complex and costly job so isolation is a quick 'fix'. I wouldn't want to re-use a disconnected immersion heater without it being checked for safety.

Simon72 wrote: »

At the time of moving in my landlord pointed to the switches and said ‘that’s for hot water’ but its only now I’m starting to realise what everything is.

Any changes made to the system need to be done by a qualified person - it won't be cheap. I would be surprised if a landlord with a 'that's for hot water' approach will be willing to invest in improvements which will only benefit you.

Simon72 wrote: »

To be sure I used an electrical test pen on the lower circuit during one of my E10 off-peak times and well as checking the second fuse board which I’m also guessing is from the E7 days – both show as dead

NEVER make assumptions like this. The apparent lack of power at the time you tested it is not proof that it is dead, especially if you used a test pen which are not always reliable. The circuit could have multiple timeswitches and/or thermostats involved, so may not be live when you test, but could become live at any point and without warning. NEVER guess with electricity - otherwise the most likely thing to be dead is you.

Simon72 wrote: »

I’m going to speak to my landlord and ask if something can be done, but I want to be informed first.

It is worth asking, but if he won't pay for a qualified person to do the work then don't be tempted to do it yourself.

Simon72 wrote: »

Am I right in thinking that the lower thermostat could by rewired to the active ring main and with a timer installed inline, I could then program it to work around my economy 10 off-peak periods?

The method of doing it needs to be worked out by a qualified person, but if it was me I would look at having the lower (main) element heating the water overnight (by timer) and the upper (boost) element operating by timer during the day cheap period to top up the heat for evening use. Both immersion heaters MUST be fitted with safety thermostats, so these will mean you only use electric if the water is not already hot enough.

The best arrangements for you will depend on your own personal circumstances. If you bath/shower in the morning then the water heated overnight may be enough to see you through the whole day. If you use a lot of hot water in the evenings then you may need some daytime boost.

LynnLegend wrote: »

The top element will cost a fortune so avoid using that.

That is only the case if the top element is used during the more expensive hours, or is wired to a meter which only records a single (high) rate.

If the OP only uses a small amount of hot water then only using the top element may work out much cheaper, even if occasionally used at more expensive times of day. There is no point heating the whole tank if you only use a couple of gallons of hot water a day (e.g. you use a separate electric shower). The cost of heat-loss from even a well-insulated tank may offset the additional cost of topping up the heat when required.