The arrangement for your storage heaters sounds fairly conventional in as much as there are two separate circuits. I'm prepared to wager that you also have two immersion heaters in your hot water tank if you have electric water heating. The lower element is fed via the timer switch and only operates on off-peak electricity. The upper element is fed from a conventional 'always on' circuit via a switch that allows you to 'boost' the tank if required during the day,
Likewise, the storage heaters will often also have two circuits. The timed off-peak circuit for the main heating and an option to boost them from the always on circuit during the day if need be.
Now let me open up a right can of worms for you! There should be four big heavy duty wires going to the time switch. L and N from the meter and then the L and N outputs to the second consumer unit for the heating. So far so good...pretty standard for E7 heating, but...do you have a couple of thinner wires between the time switch and the meter? If so, your problems all become very clear.
That time switch not only controls a set of 100A contacts to switch the heating itself, but actually send an auxiliary control signal to tell the meter itself whether it should be recording on peak or off peak units. That is to say, the time switch is also what is known as a ratechanger. More crucially, as seems to be the case, if the time switch fails, then so does the ability for the meter to switch between peak and off peak units.
So, unless an identical rate changer timeswitch compatible with your particular meter is fitted, your system as it stands is basically scrap.
Those devices and the compatible/complimentary meters have been obsolete since the mid 90's.
Here is what I would do if it was my installation:
Get E.On Next to replace the old meter with a new smart meter. That will sort out the metering issue. Meters are available with five terminals with an internal 100A contactor which can be programmed for E7, with the fifth terminal giving you the switched Live for the heating circuits. The single Neutral coming out of the meter would need a Henley block to split off a second Neutral for heating.
However, success for people with storage heaters seems to be rather mixed...some folks have been left with no heating or hot water because although the meter itself works as a two rate E7 meter, the technicians can't always figure out the auxiliary contact programming.
But assuming they do get it right, it's the solution to the problem that requires minimal work.
Your idea of replacing spurs with conventional 13A sockets and using plug in timers will work with a straightforward four terminal E7 meter, but any slippage of time, e.g. during a power cut or anything could affect the synchronisation of heating times with the E7 off-peak times. That is to say, you have no synchronisation with the meter, but you do have time control of each individual heater. You would still need the L and N coming from the new meter to be split using two Henley blocks in order to feed both the main and the heating consumer units.
If it was me doing this, rather than use 13A plugs and plug in timers, I would use a hard-wired immersion heater timer that fits a standard back box and retains the existing storage heater cable. Such timers are designed to switch high current heating loads...plug in timers will do the job but they need to be very heavy duty.
A third option is to simply replace the meter and then fit a new heavy duty timeclock such as a Sangamo. This may need a little tweaking with the wiring. but will effectively do what your current setup is supposed to do. Again, the meter tails will need splitting, then the timer can be installed in line with the second consumer unit.
Bottom line...your meter can't change tariff by itself, it needs the switch signal from your timeclock/ratechanger. And if the timer is kaput, so is the meter, by definition.
In your situation, because it is a ratechanger timeswitch controlling the meter as well as the heating, it IS an integral part of the metering system and IS the responsibility of E.On Next to remedy.
Exactly the sort of job I would do myself, just for kicks, but I never came across this exact setup with Southern Electric...they either used Radio Teleswitch, or dual (Black and white) meters and a standard timeclock.
You might be able to infer from my username that obsolete stuff, and how to try and keep it working, is something I'm interested in. This is very solvable, but if the meter technician is a youngster, possibly born after your house was built, then I'm not surprised there has been a lack of understanding on their part. They've probably never used a Betamax video recorder or dial-up internet, either.
Last edited by retrotecchie; 06-11-23 at 01:59.