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Albot81
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November 18, 2024
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Smart meters + direct unvented water cylinders + THTC. Any advice welcome!

  • November 18, 2024
  • 32 replies
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Thanks all for all the various valuable info about meters, the switch overs and installations etc pending. We currently are in the West of Scotland (mainland), have all electric and old economy 7 box etc. On the THTC. The folks at OVO I've spoke to already have offered economy 7 (overnight), economies 9 and 10, which is basically split over 3 periods in 24 hours. Questions are i suppose is as currently we're on overnight off peak, but aware that the off peak would be split over the day, which may be handy for being savvy with new style electric Quantum heaters we have (got rid of the old brick ones) and timings. The direct unvented water cylinder we have is 210 litres, any ideas whether then this would be heated 3 times a day for example with economy 9 or 10 rather than the current overnight? Plus am guessing it would be 2 smart meters for on and off peak? Many thanks, aware lots of this may have been already answered in various places, but just before i speak to them again about getting some engineers here.

    Best answer by Firedog

    Smart meter installed/replaced today, 
      

    Congratulations on your new toy! It may take some time for everything to settle down, but keep an eye on things and come back here if something’s not quite right.

    About hot water: a tank like yours probably has two 3kW immersion heaters, of which the upper one is for the boost. It takes about 11kWh to heat a full tank from cold (I used 10ºC to 55ºC), so that would take 3½ hours. You could do that three times every day if necessary at offpeak rates, but I doubt you could ever use that much hot water. I suggest you watch it carefully, e.g. switch it off one morning when you get up to see just how long the hot water lasts. You may be surprised. If you leave it on all the time, you may end up wasting electricity just to keep the temperature high in the tank when it’s not really necessary. (I’m afraid I’m not au fait with the differences between vented and unvented tanks, so I stuck to ‘O’ level physics.)

    32 replies

    Blastoise186
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    Blastoise186Super User
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    November 18, 2024

    Hey ​@Albot81 ,

    I can confirm the migration to Smart Meters would place you on a setup with ONE Meter that does everything your current Multi-Meter setup does. It just has some extra magic tricks to cover the extra wires and ensures that both Peak and Off-Peak are properly covered.

    With the Smart Meter based setup, everything that only runs Off-Peak will come on together based on whichever tariff you’re on. If the heating is set to charge up based on Economy 10 for example, the hot water will do the same.

    Hope that helps!

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      Albot81Author
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      November 18, 2024

      ​@Blastoise186 thanks so much that makes perfect sense and ta for explaining that. We have an Economy 7 style 'boost box' for water heating. Guess this would be redundant or need updating? Hoping to use it less anyway as will be getting more water hearing through the day as opposed to just overnight as at present. Unsure if that would be on OVO to update too. Thanks again.

      Blastoise186
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      Blastoise186Super User
      Super User
      November 18, 2024

      I could do with seeing photos of the boost box. Can you post some for me?

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      Albot81Author
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      November 18, 2024

       

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      Albot81Author
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      November 18, 2024

      It's always been set to timed, but if hot water needs a boost say evening time, or had lots of use more than normal, give it a boost outwith of off peak obviously.

      Blastoise186
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      Blastoise186Super User
      Super User
      November 18, 2024

      Gotcha, thanks!

      You can basically just leave that alone. It’ll probably become redundant but I’m afraid it won’t be OVO’s responsibility to remove it IIRC.

      It’ll probably cease to do anything useful but you could always ask an electrician to check if it still works and/or seek to remove it later if you want.

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      Albot81Author
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      November 18, 2024

      Again makes sense thankyou! In your opinion boxes like this won't be necessary so much with the switch? Just wondering if a boost is needed even in the smart meter world?!

      Blastoise186
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      Blastoise186Super User
      Super User
      November 18, 2024

      I was actually just digging deeper. I get the feeling OVO might rip it off the wall for you anyway. Seems like that specific model is directly linked to the meter - which may make it in-scope for removal as part of the upgrade job.

      I also found a wiring diagram that suggests it’ll just become an ornament if the linked meter is removed.

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        Albot81Author
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        November 18, 2024

        Ahhhhh, that makes sense! But likely not replace it for a model that links in with their new meters/system?

        Blastoise186
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        Blastoise186Super User
        Super User
        November 18, 2024

        They’ve thought of that. Everything will be part of the meter itself. :)

        Fancy magic tricks means that all the random boxes on the wall have been combined into a single meter for most installs. In some cases, external contactors are used to cover additional terminals, but they’re not usually needed for Economy 7.

        You’d be able to trigger Boost functionality via the Meter if you needed it.

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          Terms & ConditionsAccessibility statement

          OVO Energy Ltd, Floor 5, Crescent, Temple Back, Redcliffe, BS1 6EZ, (Company no. 06890795) registered in England and Wales.

          OVO (S) Gas Limited is registered in England and Wales (Company No. 02716495) at Floor 5, Crescent, Temple Back, Redcliffe, BS1 6EZ.

          OVO (S) Gas Limited is part of OVO Group Ltd