E7 - % threshold for switching away - has it changed?

Richie-from-the-Boro

Dimplex

bettybadger

Have been looking at a few similar fan heaters this morning after macman's tip - didn't realise how inexpensive they were.
However, I then dug out the 2 quotes I had from a heating engineer and remembered why the project was put on hold. Quote for dropping in a radiator from the CH system (& removing storage heater) - £491. Quote for installing an electric panel heater & re-wiring it off E7 onto standard (plus removal of storage heater) £385.
Think we decided as there was little difference, we'd be better off waiting till we could afford to put in a radiator as it would cheaper to run.
Do I presume rightly it would cost almost as much to have a fan heater fitted? (Fan heater a bit cheaper than panel heater but same amount of labour to remove storage heater, rewire & install?) Maybe I should ring round for some more quotes.....

jives11

HI, interesting thread.

Does anyone have a formula to determine the break even point between standard and E7 tariffs for a given supplier ? I used a spreadsheet where I set the ratio of off-peak to total (off+on peak) and changed the percentage ratio until E7 was cheaper. I'm in the SSE region but use Ecotricity , and for me the break even point was something like 28.9%


I guess there is an equation to calculate the number precisely , but my maths is very rusty.

I log my weekly use with imeasure.org.uk and can see that some weeks I just scrape by at about 30%.

I have some white goods (WM, Dryer, dishwasher) with delay timers and use a bit of immersion heat overnight and its quite hard to get much beyond 30%.

I think without storage heating or some other factor , like unusual working hours, its hard to make it economical, though it does have slight green advantages.

macman

You don't need a spreadsheet. Just put your annual kWh figures into any comp site, once with single rate, and then again with E7 and your 30% split (or whatever percentage you want to calculate on).
A weekly calculation tells you nothing, it's the annual figure that counts, because it's the night rate heating factor in winter that makes E7 feasible.
There is no set formula, it depends on consumption, region and supplier.

Cardew

As above - it really is that easy.

jives11

Thanks , I agree but I don't have Electric heating. I have E7 and I do use some overnight immersion, but my usage is broadly the same all year round. I agree that were I using storage heaters in winter, the heavy off-peak in winter would oiffset the light/non-existent use in summer. My situation is slightly different. Your right that I should look at a complete year, but I like to try to achieve 30% or better all year round

macman

Why do you need to achieve 30% each week or month, which is what I assume you mean? What matters is the split in terms of annual usage-since the annual cost is the only figure that matters. If you did have NSH's, then you would not achieve 30% all summer (maybe less than 10%)-but the night rate usage in winter might push it up to 50% or more.
Either way, the answer can be found in less than two minutes via a comp site.

lstar337

macman wrote: »

If you did have NSH's, then you would not achieve 30% all summer (maybe less than 10%)

We manage it, but it isn't always easy.:)

June - 39%
July - 42%
August - 37%

But we are low users, and we try hard to shift as much of our use to night, as we can. During summer we can sometimes use as little as 3-4kWh/day. Even with NSH off, our hot water will offset the peak day rate.

macman

lstar337 wrote: »

We manage it, but it isn't always easy.:)

June - 39%
July - 42%
August - 37%

But we are low users, and we try hard to shift as much of our use to night, as we can. During summer we can sometimes use as little as 3-4kWh/day. Even with NSH off, our hot water will offset the peak day rate.

Well done-but I'd say that your percentage split is not achievable by most users in summer. But that doesn't really matter-what matters is the annual split, unless you are switching betwen E7 and single rate every 6 months.