Storage heater wiring questions

MrBrindle

Morning,

Can someone offer me some advice on storage heater wiring?

We are on an E7 teleswitch / timerswitch meter thing, and after a bit of discussion with our energy suppliers we discovered our low tariff runs around 1.30am - 8.30. Which is fine by us, cheap showers in the morning!

Anyway, our electrician came to install our storage heaters this Monday. I know how storage heaters work, and have done an ocd amount of research on them and other methods of electrical heating as we had no other option. After he finished, he left us instructions explaining how to control the heaters, telling us we have to manually turn them on and off at night and morning to stop them constantly charging. This made no sense to me, as they should only be charging during E7 and defeats the purpose of having them. Everything is wired into the same fuse box at the moment, but now he suggests that he should have a separate fuse box just for the storage rads, and wired directly into the E7 meter.
He also thinks that the previous owners of our house rigged the meter so E7 starts at 10.30, which I don't understand after getting clarification from our suppliers and also testing it ourselves to see when the E7 kicks in.

The only question I have if he wires the rads directly from a separate fuse box into the E7 meter, will we still get E7 through the rest of house?

malc_b

Sounds to me like your electrician hasn't done it right. What you should have it a E7 meter and time clock. The time clock is sealed and has a spring reserve to cope with power cuts (maybe the have electronic versions now but that was how it was done in the past). You can see the on/off times and the current time on the time clock so from that you can work out what you actual E7 hours are. They are unlikely to be exactly 1:30 to 8:30 since it depends on how accurate the bloke's watch was when he set the clock.

The time clock connects to the meter and changes the rate low/normal. With a E7 heated house the time clock also usually drives a contactor (heavy duty relay) which also turns on the E7 heating. My mother, who has E7, also has box which senses the outside temperature overnight and adjusts the heater charge by delaying the turn on of the contactor on warmer nights. In her system the contactor is between the electricity board fuse and a second fuse box. Each heater has its own cable and own fuse in the second fuse box. I guess that contactor could be after the fuses if it had enough ways, so you could use a single fuse box. Or you could have a split fuse box.

Sounds to me like the new heater has just been wired off the ring main and without a time clock. Running a new cable back to the fusebox is not easy so maybe that is the best approach but it should have had a time clock, and remember that this will be quiet a load on the ring main overnight which might be an issue (if for example it is the only ring main in the house, so at 8am breakfast if the storage heater, kettle, toaster, etc. are all running you may trip, a ring main is 32A so 7680W maximum load).

BTW 1:30 to 8:30 is during summer time, it will be 12:30 to 7:30 during the winter.

Cardew

I have an Economy 7 meter and tariff, although with gas CH.

The house is wired so all electricity consumed during the 7 hours off-peak period is recorded on the E7 register(display). So were I to fit storage heaters(I obviously wouldn't) or use the immersion heater overnight they would need to be on individual timers or manually switched on and off. Unless I did some extensive changes to the wiring of the house.

Another Economy 7 system widely used is for only the storage and immersion heater circuits to be 'live' during the 7 hours and the rest of electrical circuits be on the daytime rate 24/7.

If you adopt your electricians suggestion - assuming you wish to use the immersion heater on E7 - you will not be able to top up your hot water unless you fit another immersion heater in tank.

AndyPK

Yeah you need a big timer to turn them on and off.

You still need to adjust the knob on the top though for the flap setting

MrBrindle

Thanks for the reply. I suspected so.

I believe what we have after speaking to our supplier a few weeks ago is a radio controlled time switch.We press the blue button and it switches between the time, normal tariff, low tariff, total tariff etc. There's also some old style spinning meter thing next to it. So are you saying we should have some sort of timeclock as well?

Yes everything is on the main circuit at the moment, and I REALLY don't fancy laying down new cables and chasing walls. Is there really no way that this could be changed without doing all that, fitting in a timeclock somewhere?

He has advised not contacting my supplier for some reason about this, but I feel like I have no choice because I really need to understand whats going on.

MrBrindle

What I'm trying to understand is can the heaters, if on a separate fuse box, be directly wired into the radio controlled timeswitch meter somehow?

muckybutt

Hmmm not a great way of doing things !

Your electrician should have installed a dedicated consumer unit for the E7 and wired all the heaters to that - that in turn is wired into the teleswitch or via a contactor.

As it stands now you will need to fit timers to all the storage rads, problem you might have is if the SR's are bigger than 13A, ideally you want to fit something like http://www.tradingdepot.co.uk/DEF/product/!!FST11A!!/?gclid=CPW_xeKfr7oCFXMRtAodsRcAvQ which is a fused 13A rated timeswitch or a http://www.neweysonline.co.uk/sangamo-daily-multi-application-time-switch-powersaver-16a-230v-ac-50-60hz/1050103635/ProductInformation.raction which is a 16A rated time switch.

MrBrindle

Hi Mucky,

He has suggested putting in another consumer unit for the storage rads, is that a big job? He's trying to put us off changing it due to the cost involved, and sticking to the plan of manually turning them on and off, which I'm pretty annoyed about tbh.

muckybutt

It can be a big job ! do you have floorboards down stairs ? a decent electrician that knows what they are doing should be able to do it in a day two at the most, new boards aren't that expensive.
You can buy a decent MK one on line or at B&Q for less than £100 with breakers.

Turning them on and off all the time is a bit of a pain to say the least. I would expect the board, cable and labour to be around the £400 - £500 mark.

MrBrindle

Oh dear, I wasn't expecting there to be the need to chase down walls and lifting floorboards for more cabling - I thought if the cable was there it could simply be re-arranging them by the consumer unit or something? We only had the house re-wired back in March by the same electrician and we specifically said storage heaters were needed, and I presumed he knew the correct way to arrange the cabling etc. If that's the case I might just ask him to remove the lot, refund the money, and make do with just panel heaters.

Gloomendoom

It sounds like new circuits will be required for the heaters. The cost is likely considerable if you aren't a fan of surface mounted cabling.

Separate timers may be the best option.

We had storage heaters and they were wired to a separate CU fed direct from the meter via a big time switch. The wiring is hidden in the walls and under the floorboards. The E7 teleswitch was completely separate and only switched the meter from normal to low (still does.)