Night Storage heaters in an outside building

[NewbieNeil]

Hi all,

I have just put together, but not wired up, two new storage heaters in an outside building. I will be getting an electrician to do the work, but I would like to know my options.

The meter in the house has a day and night reading, but everything we use in the house at night is on a timer as we don't have, nor need, an economy 7 circuit in the house.

In the outside building the existing cable runs into the consumer unit and provides two rings and lighting etc. If the two 3.4K storage heaters are on a separate ring is there a timing device that can be fitted to the consumer unit to decide when power was drawn or does a timer have to be fitted to each socket? Running a second cable outside would be horrendous as they didn't allow enough room!!

I hope that I've given enough detail.

Thanks,
Neil

 

[ricicle]

Is your dual rate meter set-up so that the whole house becomes off peak during the night ? If so just use a timer to bring on just the night storage heaters at the same time as the off peak.
If not it can't be done without extra cabling. We can't see the exact set-up so you are better off asking your electrician anyway....like does this building have a supply big enough for an extra 6.8kW of load ?

Ps Storage heaters are usually wired as radial circuits not rings !

 

[NewbieNeil]

Hi ricicle,

Thank you for taking the time to reply.

Is your dual rate meter set-up so that the whole house becomes off peak during the night ? If so just use a timer to bring on just the night storage heaters at the same time as the off peak.

I think it must be, as we definitely have no economy 7 circuits and we are using night units for the washing machine/dishwasher etc.

If not it can't be done without extra cabling. We can't see the exact set-up so you are better off asking your electrician anyway....like does this building have a supply big enough for an extra 6.8kW of load ?

Thanks, it shouldn't be a problem as they will be the only equipment drawing power overnight.

Ps Storage heaters are usually wired as radial circuits not rings !

Out of interest, what is a radial circuit?

Thanks again,
Neil

 

[ban-all-sheds]

//www.diynot.com/wiki/electrics:socket-circuits

 

[NewbieNeil]

//www.diynot.com/wiki/electrics:socket-circuits

Thank you for the explanation ban all sheds.

Neil

 

[EFLImpudence]

Just a further point to ricicle's.

You need to make sure that you do still have E7 which you can use for the heaters. Are there two amounts on the bills?
If you do still have E7 but nothing is connected to this supply (i.e. previous items disconnected) then you will be paying more for your usage than if you had just standard tariff.

 

[NewbieNeil]

Hi EFLImpudence,

You need to make sure that you do still have E7 which you can use for the heaters. Are there two amounts on the bills?

Yes, we are billed for day and night.

If you do still have E7 but nothing is connected to this supply (i.e. previous items disconnected) then you will be paying more for your usage than if you had just standard tariff.

In the twenty five years I've been in the house there has never been anything connected permanently to economy 7. As I'm receiving a bill for night and day units am I missing something here?

Thanks,
Neil

 

[westie101]

It was a common selling point of E7 that you didn't need storage heaters.

By running washers, dryers etc. and immersions overnight on timers you could still show a saving.

 

[EFLImpudence]

As I'm receiving a bill for night and day units am I missing something here?l

No, that sounds ok - just checking.

Some customers have storage heaters taken out but don't bother to have supply changed, leaving them with higher 'E7 day rate' for everything.

 

[NewbieNeil]

As I'm receiving a bill for night and day units am I missing something here?l

No, that sounds ok - just checking.

Some customers have storage heaters taken out but don't bother to have supply changed, leaving them with higher 'E7 day rate' for everything.

Thank you for checking.

Neil

 

[flameport]

In the twenty five years I've been in the house there has never been anything connected permanently to economy 7

Unfortunately this probably means you have been paying too much for your electricity, certainly in the last 5-10 years.

The 'day' units will have a higher price than on a normal tarrif, and although the night units will be cheaper, it is only cheaper overall if you use a significant percentage of your electricity at night.

In the past, the difference between E7 day and normal units wasn't that much (if anything), but it is now - and as most appliances use far less electricity than their older equivalents, using a washing machine at night won't be anywhere near enough to offset the increased costs of the rest of your electricity.

As an example, Southern Electric standard prices currently are:
Standard tariff 11.91p
E7 Day 13.83p / Night 6.05p

Therefore on E7, you are paying 16% more for the daytime units, and would need to use about a third of your electricity at night before any savings were made.

Other suppliers and price deals will vary, but the ratio of day/E7day/E7night isn't usually much different.

 

[Stoday]

The original honest, before privatisation, basis on which the E tariff was set, was that an average domestic consumer would pay the same on an E7 tariff as on his normal tariff, except that the standing charge would be a little higher to reflect the extra meter cost. The night price was set to the Bulk Supply tariff’s night charge which reflected the marginal cost of nuclear generation. The day price was then set so that the overall price equated to the normal price for the average consumer.

The average domestic consumer used (and still uses) around 15% of his electricity consumption in the E7 night hours. Thus if the normal rate were 10p/kWh and the night 6p/kWh, the day rate would have been 10.71p/kWh

The higher day rate made it difficult for a consumer to work out if he’d be better off on the E7 rate or not. So to make it easy, some electricity boards (as they were before privatisation) equated the normal and E7 day kWh rates and balanced revenues out by adding to the standing charge. The average domestic consumer uses 3300 kWh a year, 495 at night. Thus the standing charge is increased by (2805*0.71) £19.92 a year. That introduced a cross subsidy in favour of larger consumers.

There has been no Bulk Supply Tariff since privatisation. The market that superseded it does not have night prices. In fact, no one has a clue how much night electricity costs or what the price should be. So the E7 night rate is guessed. To make sure they don’t lose out, suppliers overcharge on the day rate. So Southern Electric equate for a 25% night consumption. But not all suppliers do so. Some remain at 15%.

It’s not possible to categorically state that someone having no off peak circuits is paying too much. They are better off on E7 if they use a greater proportion of night kWh than the supplier’s target. That may be as low as 15% but can be higher. If you are on E7, you can work out your % night kWh from the day and night kWh on your bills.

The supplier’s target % night rate id (D –U)/(D-N), where D is the day price, N the night price and U the normal price. For example with D=13.83; N=6.05 and U=11.91, then the target is

(13.83-11.91)/(13.83-6.05) = 1.92/7.78 = 24.7%

You have to take any difference in standing charges into account as well.