I shoiuld have added that the 30 years old Dimpex storage heaters dont have a timer that switches them on/off. 

Hey ​@dutyhog ,

This sounds like expected behaviour to me. The 10 minute thing is part of the random offset designed to avoid blowing up the grid - it’s fairly similar to the behaviour you would have seen with RTS and IIRC it’s kinda intended to replicate that fairly closely. The biggest difference, however, is that Smart Meters do all the switching stuff locally and don’t rely on control signals. It only requires the signal once to pull down the configs and after that, it’ll run by itself forever regardless of whether it can communicate with the WAN or not. I do note however, that based on the Comms Hub you mentioned, you’re running on the Cellular WAN. It’ll either be the Telefonica WAN running on 2G/3G, or the Vodafone WAN running on 4G. I can’t say for sure as I don’t currently know - but I wouldn’t be surprised if it’s the new 4G link.

As for the potential for billing issues… It could be argued that by the time you get to the end of Off-Peak, most Storage/Immersion Heaters will have pretty much had their entire fill and stopped taking a charge anyway so the extra costs are likely minimal.

I’ll fling this to the Forum backstage in the next couple of days though, just to be sure.

Thanks Blastoise186.

Nick said he’d installed it to work with O2, ie the Telefonica WAN (which I use for GiffGaff 4G to get my internet signal).  

Our old storage heaters can still be on quite high power at the end of the off-peak period. I was waiting to see how the digital switch went before working out how to replace them with something more efficient.  We’ve had some quotes, and it may seem best for us to stop using storage heaters altogether and have the convenience of heating us just when and where in the house we want (we are long retired and at home most of the time now). Maybe we can find out by experiment if that seems OK using the main storage heaters’ convector heater circuits instead of the storage circuits.

But my main point is that the meter, whether switching locally or remotely, ought to change tariff and switch off-peak simultaneously, regardless of the necessary offset of time from the nominal periods advertised.

Gotcha - bear with me and I’ll send this backstage in just a sec. Gotta catch up on something else real quick first!

I don't see a problem as the off peak energy used is switched to the off peak register at the same time (whenever that is). Peak usage is only accumulated in the peak register. Doesn't really matter at exactly what time that happens so long as it is somewhere near the right time. At least that is my understanding of how it works but I'm happy to be corrected though.

Peter 

Thanks Peter E,

When I follow the IHD it shows switching to the off-peak rate at 14:30 but the storage heating doesn’t come on until 14:40.    It then switches back to the standard always-on rate at 17:30  but the storage heating stays on until 17:40. It’s similar for the other off-peak periods. So I’m being charged always-on rate for 10 minutes each period. As I write I see that our storage heaters are still consuming their full power even now, 2.5 hours into the off-peak period on a (admittedly cold ) June day. That costs us 25.5p/day more than it should,  £93/year.  I think that OVO should see that as un-necessary. I know it won't save the planet to synchronise switching, and I can afford it (and more importantly afford to get some modern heaters).

This is irregular, and I wonder whether it might not settle down eventually. The randomized offset - unique to every meter - is there to prevent shocks to the network caused by many power-hungry devices - like storage heaters - being switched on at the same instant. It is supposed to act on both the tariff switching timetable and the auxiliary load control switch (ALCS) timetable, so they should be perfectly synchronized so long as they’re set to the same timings. 

I’d suggest having a look at the meter itself to check when the tariff changes. You may have to experiment a bit with the buttons to find out just how yours is set up, because the menu options are configurable, so your menus won’t necessarily be the same as anyone else’s. On my own Aclara SGM 1416-B, repeated presses of orange button B eventually reveal a screen headed Active TOU Number, giving the number of the active tariff register. This will change from 1 to 2 and back as the tariff changes.*

Another indicator is in the bottom right-hand corner of the display, two little icons labelled (on my own meter) ı and ıı. The upper one shows the state of the internal contactor for the constant (always-on) circuit. The lower one is for the switched-circuit contactors. 

The upper one (ı) should always be closed unless the power has been cut. The lower one should be open during peak hours. During offpeak hours, it will not show open. What it does show depends a bit on how the internal switches are configured; on my meter, when offpeak kicks in, I see  LC1 LC2  indicating that both the 100A contactor for the storage heaters and immersion heater and the 2A switch for a (non-existent) external contactor are closed. 

 
So, having established that your switched circuit is energizing at ~10 minutes past the nominal time, you should watch the meter display screen from a minute before the nominal switching time to ten minutes later. You should see both indicators  - the Active TOU Number and the load control switch icons - change simultaneously. 

If they don’t, I’d suggest you take a clear photo of the meter, with the display screen illuminated and showing the Active TOU Number and the lower load control icon in the wrong state. The picture should include the Meter Serial Number (MSN, which is the number starting with the two-digit year of certification followed by an ‘M’) and - if you can work out how to do it - with a watermark giving the precise time and date. You then have some concrete evidence to present to the smart team if the meter doesn’t start behaving itself in a day or two. I’d expect the IHD to fall into line eventually, too.

*  The meter should have been configured to record peak consumption on register tier 1 and offpeak on tier 2. This should be the default nowadays, but it’s always possible that a meter is misconfigured in this respect. Please check carefully that the Active TOU Number is 1 during peak hours ... 

​@dutyhog thank you for your post, and a massive thanks to ​@Blastoise186, ​@Peter E and ​@Firedog for your brilliant help as always.

I’d also like to tag one of our experts ​@Lukepeniket_OVO to see if he has any helpful advice here.

​@dutyhog please let us know how you get on following ​@Firedog’s advice, we’d appreciate it.

Cheers!

As always with meter issues ​@Firedog comes back with a more compete answer than mine

Thanks very much all, especially for Firedog’s detailed suggestion.  The meter is outdoors and it’s a very wet day, so unless it gets drier this afternoon it may be tomorrow before I take the photos.  

Hello Firedog - here’s a time-stamped photo of the meter at 11:59 today during a peak period, TOU 1.  It seems to be set up like your description (apart from no LC1 etc yet).  Unfortunately the screen is very scratched, especially over the switch icons, so it’s difficult to light it well.  But you can see that the switching is as expected.

From it’s number it seems to be an old meter - 2021 - maybe it’s been used before?

Thanks. That’s just what I was hoping for. I know that there have been supply problems with Aclara meters, so it may be that they’re having to resort to installing refurbished ones. It’s a bit surprising that you got one with a damaged screen, though. So long as the meter keeps communicating both with OVO and your IHD, you might never need to look at the meter again once we’ve got this present wrinkle ironed out.

Now you know what’s required, you have to check whether the two timetables (the tariff switching schedule and the ALCS calendar) are aligned as they should be or not. When you spot the icon change, it’s a good idea to note the exact time. This won’t ever change unless there’s a significant shift in the meter’s clock, so you know when it’s safe to turn on power-hungry stuff like electric showers and tumble dryers - even hoovers. Running these at offpeak rates can save a lot of money over a year.

Hey all! 

I like this one and will do some digging but regardless of what the IHD say the Tariff timings will be set by the meter so if there is an offset it should be charged correctly! Im now going to go into the rabbit hole with this one.

Soo funny to see Nick F name here! He lives down my way and we regularly have contact

You know what they say Luke, it’s a small world! XD

Here’s a sequence of time-stamped photos taken around the start of the afternoon Economy 10 off-peak period. There’s a nominal 1430 switch on. Again the IHD showed the tariff going down to 22.28p at about 1430. The storage heaters came on 10 minutes later. But the meter showed TUO 1 at 1439 then TUO 2 at 1440, confirmed by the botton RHS symbols.  So it seems that the meter is OK, therefore my billing should be OK. I’ll find out how it goes around 1730 (probably 1740) when it should switch back again.

That is quite brilliant, so thank you so much for taking the trouble to document the changeover. Assuming the other time slots show the same behaviour - and I can’t imagine why they shouldn’t - the only fault left seems to be the IHD’s tariff-change timing. That may come right in due course, but it’s not in any way critical. If it’s still out of whack when the installation is six weeks old, ask Support to update its tariff configuration. 

We haven’t mentioned hot water. I rather assume that you have an immersion heater, wired to the same switched circuit as the storage heaters. If there is a local control by the hot water tank that restricts its normal heating schedule, check that this too matches the new tariff switching times. It may not be necessary to have the immersion heater on for more than the early morning slot (05:39-08:39), so watch out for waste there. If you have an electric shower, be sure to use it only during offpeak hours.

One last comment, in response to your original post’s “I thought that the signal change would coincide with the tarrif change.” The timings are all set in the meter on installation, so there is no relying on a signal to switch anything like RTS did. A couple of times a night, OVO will connect to the meter and ask it to send meter readings and usage data. Unless the meter needs an update (e.g. when tariffs change), this is about all the traffic that the meter will be involved in. 

Thanks again, Firedog, for the very helpful responses.  For completeness here are the photos over switching back to peak tariff. You can see the IHD changing from off-peak to peak rate at 1730, then the meter showing heating connected and active tariff  22.28p (I was too slow and missed the TOU) at 1738, then heating off and TOU 2 at 1739.

I'll try to be patient and wait 6 weeks now for it to sort itself out.

I didn't want to complicate the issue with mentioning hot water. The water tank has a bottom immerser with an off-peak connection and an upper immerser always on for boost. The latter was always off-peak with the THTC meter, but not now.   We have a passive solar water heater (Solartwin with its own PV panel for its pump and controller) and tended to use that when possible rather than the bottom immerser, plus the boost at times. After 17 years its heat-absorbing rubber hose sprung a leak inside the panel, and I intend to get it off the roof and replace it. That investment should pay for itself within a year.

Thanks again. I think you can take comfort from the meter’s “Active Tariff Price 22.280 p Per kWh” at 17:38:32 and expect to be billed at offpeak rates for all usage during the precise offpeak hours you’ve now identified. 
  

You might have a look at alternative tariffs; I see that there is currently a one-year fixed Economy 10 price offering with significantly lower unit rates but higher (£12 p.a.) standing charge. The Simpler Energy rates will fall next month, so you can have fun trying to make meaningful comparisons. If you visit switch.ovoenergy.com, you may be able to get E10 quotes, in which case they will be using the rates due to enter into force on 1 July.  

(I keep thinking of more things to say ...) I’m fairly sure the switching times are set in UTC, so they will all change when summertime ends on  26 October to one hour earlier than today’s.

​@dutyhog Hope you are well and apologies for taking a few days to get back to you. 

Everything is functioning as it should! Youve got a random offset applied to the meter to turn on the ‘extra load’ 575 seconds after coming into and out of the off peak window (Youll hear the loud clunk on the meter when it starts/ends), everything fed by the meter will be at the lower rate at this time.

Your IHD isn’t as smart as the meter and will show when you enter the off peak timeslots but without the delay of 575 seconds, so bear that in mind when look at the IHD.

It seems that the IHD does it's own timing for peak and off peak periods then and is not actually reflecting the status of the smart meter which applies a random time offset. That is a useful bit of information to know.

I’m wondering about that message Tariff rate will change. Of course there will always be a tariff change ahead, so could it be that the message only shows in the period from 60 minutes before the nominal change time to the end of the randomized delay? I’m sure I’ve seen other customers documenting a change of tariff on the IHD at the end of the delay. The countdown scale is also showing that the change is n minutes ahead, perhaps 1<n<10. 

It’s annoying if the IHD can’t be relied on to indicate when it’s safe to have a shower or when it’s time to turn the oven off. 

Thanks, Lukepeniket_OVO

It seems odd that the IHD hasn't been programmed to read the tariff that the meter will display. I can’t imagine that there isn't enough capacity to transmit, receive and store the small amount of extra data (unlike all those years ago when, with slow computers and little memory, I needed to write and endlessly debug machine code rather than high-level languages to run a machine).

Firedog: The countdown seems to start 60 minutes before the nominal change rather than the actual. The displayed 10 minute steps makes it a bit vague.

We’ll just live with the offset, and treat the IHD indication of the tariff changing as early warning to switch things on or off if convenient.

Machine Code. Luxury! We used to dream of writing machine code. We used to have to manually punch cards and feed them into a card reader and hopefully not chew them up.

That was actually true in my case for an Elliot 803. The kids today don't know how lucky they are …

Peter

Peter, this is turning into a Monty Python Yorkshiremen boasting session.  I often used a slide rule until about 1978, but started computing in 1962 with 5-hole paper tape. A company I was in had an IBM stand-alone computer around 1972 with card input. I thought that cards were a big step up. The deal was that you joined a queue with your stack of cards in your hand. When your turn came you put it into the reader and watched it run, and finished when it did the job, or more often crashed. The next person in the queue was always keen to get on. You may have had to wait hours before getting back on again.  I wrote a program that could have needed to run for a week, and managed to hog the computer for hours by making it pause often to let me read the printout to change parameters by shuffling into the input pack cards with altenative code or data that I'd prepared in advance to cover many eventualities. Fortunately it only needed a couple of hours to get an answer, good enough to provide a patentable design that solved a big problem.  Nowadays I suppose it would take seconds on a Raspberry Pi with an SD card for storage.  Or even maybe a spreadsheet could do it?

I've just paused to see if GPT-4o mini could show me a design to solve the problem. In seconds it came up with an answer with full details and  explanation. My patent deliberately hadn't given all that useful detail. Maybe it got it from someone who found the answer since 1972 and published it. Maybe it guessed because it looks as though it may be wrong - I’ll check tomorrow.