New Storage Heaters showing Economy 7 not for full 7 hours

I just had new Dimplex XLE Storage Heaters installed that support Economy 7. Having studied the manual properly, I found these relative new heaters can display all kinds of stats - There are even newer models called Quantum that are supposed to be even more efficient but I am happy with the XLE’s so far. The important stat here is the time the E7 is on - 410 minutes if both XLE’s I have are reporting accurately. If true, this means the meter is robbing me of 10 minutes and the heaters are not storing up to full capacity. My meter is a relatively new digital meter (not smart) could this be at fault?

It’s common for there to be a few minutes of jitter added to the official start time, so that every single E7 meter on your local distribution network doesn’t switch on at the same time putting a massive inrush current through the transformers.

I get no jitter as E7 comes on and goes off at exactly the same time each night with the digital meter. Starts at 12:40 am GMT and off at 7:30 am, so I am cheated out of 10 minutes each night.

Sorry, I didn’t mean to imply that the jitter varied per night.

The 10 minutes is your jitter. Other properties will have different amounts.

Great, then of course if Bulb refer to it as normal jitter, then of course they don’t let any meter exceed 7 hours and take some minutes off some people, or perhaps everyone? In my case the meter should be allowed to use E7 until 7:40 am, so get the full hours.

I’m not sure if the jitter ever causes the meter to switch earlier than expected, meaning some properties would get a few minutes more off-peak time. I think it’s only ever a delay. This isn’t under Bulb’s control by the way, it’s defined by the distribution network operator.

They just don’t come bulb say I’m on e7 tariff and they should but as a sparky of 40 I know how it all works lol they just won’t admit they are at fault
The heaters work on the boost button so the system and meter are all working as it was before we switched
Bulb you got it wrong just admit it and sort it

This is completely unrelated to the original question. You have a different problem.

If I use Boost then the heaters use Peak power which is almost twice as expensive, so obviously don’t want to use it, unless heaters run out of steam

The simple FACT is that Economy 7 is a tariff of long standing and provides for SEVEN hours of ‘off peak’ electricity at a lower price per unit, than the remaining SEVENTEEN (17) hours of ‘ON peak’ daytime electricity. Storage heaters are designed to accept a full seven hours (420 hours) of energy and not 410 hours. This is a matter for the BULB meter operator to deal with and indicates a fault with the meter installed and or the time switching device either a separate or integral to meter type. A loss of ten minutes per day will amount to an overcharge in the bill and thus a request for pro rata credit should be requested, on confirmation by meter operator that the meter is faulty.

That should have been 420 MINUTES NOT Hours !

Fun for Bulb then, the meter was installed a couple of years ago so should be last digital generation before smart meters. The timer switch is integrated so may need a new meter if timer can’t be fixed inside. I will not be overcharged because the heaters just stop drawing power at 7:30 GMT. It just means they are only 98% full, so will run out of steam roughly 20 mins early - high efficiency assumed. I have boost turned off so peak power is not used.

But you must remember that Economy 7 tariff is NOT just for storage heaters. ALL your energy usage benefits from a lower unit price for 7 hours a day. I used to advise all electricity customers to switch to E7 tariff when their ‘off peak’ use was more than 15 % of the total. Frigs, freezers use ‘off peak’ electricity plus many other devices. You are losing out by 10 minutes a day that’s 60.8 hours a year. Work it out, its easy. Electricity prices have shot up in past few years, why lose out and give money to the supply companies?

I failed to mention I have solar panels and a box that pumps spare generated power to the immersion heater, so free hot water at least for about 8 months a year. On a sunny autumn/winter day I have the pleasure of the heaters running full on with still spare power from the panels to heat the hot water tank. Just can’t use the washing machine or vacuum the house at the same time, until late afternoon when the tank is up to temperature. Good point about the 60+ hours lost will chase Bulb. Without the new tech 10 mins goes unnoticed and probably been like it for the last two year at least. Also got the FIT grant just in time as panels installed at the end of March this year. Was stressful dealing with the panicking Solar company lol. New grant will eventually replace FIT but less generous.

Have a look at the instructions for your heaters. If you have the ability to programme extra charging time, it means your heaters may not need the full seven hours to charge. The 410 you see is the amount of time the heaters are receiving power. This may not be the same as the amount of time actually charging.

My heaters charge for around 4 hours overnight and chuck out more than enough heat for my requirements. I then have the ability to programme up to an extra 3 hours charge if I anticipate a longer “on” time or a higher temperature output.

If you look at your meter, say an hour before switch over you’ll get an idea if the heaters have stopped charging. My E7 switches over at midnight and when I’ve come in just after 4am, the meter is showing no sign of any draw apart from the fridge but the minutes you mention still increment. Mine show 240 at 4am and 255 at 4.15am but there’s been no draw during the 15 mins. I’ve even come in later and it’s the same.

If your heaters don’t have the function I’ve mentioned above, then ignore what I’ve written!!

Thanks Anton, but I have checked all the figures carefully. These heaters give tons of stats. Also the Manual and data sheets give power consumption while charging and maximum capacity for each model. The result are consistent 10 minute loss and they are only 98% full e.g.

XLE Model 50 - Power Consumption while charging : 1020W
Maximum capacity when full : 7140Wh
Actual Economy 7 charge : 6970Wh

XLE Model 150 - Power Consumption while charging : 3300W
Maximum capacity when full : 23100Wh
Actual Economy 7 charge : 22550Wh

Seems very low to me. Lets take an example. Here’s the unit rates for London.

D = Day: 15.288p per kWh
N = Night: 7.455p per kWh

S = Single rate: 13.0095p per kWh

F = usage ratio = 0.15

(D * (1-F)) + (N * F) = 14.11305p per kWh

We have to increase F to at least 29.1% just to match the single rate equivalent. This of course varies by area. Ideally the minimum is 40% off-peak use in order to be sure for E7 to make a saving, and that is the value generally recommended in the literature. Recommending a switch at 15% off-peak usage will more than likely result in a higher average rate than the equivalent single rate tariff for the same area.

I understand your arguments on how 10 minutes a day soon adds up, but that’s just how it is. The jitter is not set, nor controlled, by the supplier. Switching supplier wont make any difference. Complaining to the supplier wont make any difference. If you really want to try, complain to your DNO. But you’re not going to get anywhere.

Yep I tried to talk to my DNO and they pushed me back to Bulb, sigh… I was polite but said everyone’s a middle man these days.

Fair enough. I have 3 x Quantums and they behave as I posted. My earlier post wasn’t comparing like with like.

Well done for doing the calculation based on current D/N relative unit rates. 15% would certainly be around the breakeven point some years ago and I accept that may not be the case now, it depends on your supplier tariffs. With more and more people using ‘off peak’ electricity to recharge their EV’s the situation is getting worse year by year for us who rely on night storage heaters. I suspect that before long the night time drop in demand will disappear. However, a tariff IS a tariff and like any quoted price it means what’s described on paper. 7 hours of lower priced electricity means 7 hours and not less 10 minutes and thus should be discussed with supplier and meter operator. I would NOT accept a minute less than I had agreed to on the tariff. If your supplier doesn’t agree then switch to another one and take the matter up with Ofgem. Accepting ‘jitter’ whatever that is? is going to end up with it increasing to 20 minutes or even an hour , its E7 NOT E6.6 etc .