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nathaniel2040
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January 26, 2025
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How will I heat my water when THTC meter swapped out?

  • January 26, 2025
  • 11 replies
  • 572 views

Hi All,

Had a look through the forum and couldn't quite see a thtc query that covered my questions.

Obviously I need to move to a smart meter but an OVO engineer came out but then said they couldn't change the meter because I had a thtc setup (even though this was why OVO sent him) he said he'd let them know and they'll be in touch to sort. 

I haven't had anything other than another email saying they'll be in the area and I need to book an appointment to change the meter.

I haven't had any other info on what the plan is but surmise itll be E7 or E10, I even had to go to the ombudsman last year and ended up with a significant amount of compensation and confirmation they couldn't make the change as they had no way to decommision the second mpan and I'd still be charged or my system may not work (maybe this has changed now but that was less than 6 months ago).

Anyway, my main question is about hot water as I no longer have the bigger storage heaters, I do have small ones that I can turn on as and when so don't need to store heat so to speak.

How is my hot water going to be heated in terms of just at the cheaper times? I can't find a timer as such, just the grey boost box where I can turn it on for a few hours manually, it does have a switch saying 'timed' but no function to actually adjust the timer.

So when I get the meter replaced I'm not confident I'll be able to set the times as I assume it's hard wired into the meter itself, now whilst I understand that normally a supplier wouldn't contribute to a cost out with a metering change, if the timer is hard wired to the meter itself then this is a different set of circumstances?

The additional cost part is minor but still a valid point in my opinion, my main query is what are others doing? Is your timer situation the same or different? 

    Best answer by Firedog

    I haven't had any other info on what the plan is but surmise itll be E7 or E10, …
      

    There is another option: the Standard Variable Tariff with a single rate all the time. Please check the various rates on the OVO plans page.
      

    … I no longer have the bigger storage heaters, I do have small ones that I can turn on as and when … 
     

    Sorry, this isn’t clear: are these smaller heaters storage heaters? It’s a major difference, because you will no longer have the cheaper all-day Heating rate. Your costs will all be calculated according to when you use electricity, not what for.
      

    How is my hot water going to be heated in terms of just at the cheaper times?​​​
      

    There will only be cheaper times if you choose one of the multi-rate options: E7 or E10. You would normally use much more electricity to power the space heaters, so any saving you might make by heating water only in offpeak periods would probably be gobbled up by the extra cost of running space heaters at peak rates. 

    If you do go for a multi-rate plan, then the water heater would be on the same switched circuit as storage heaters and only using electricity at the offpeak rate.

       

    The additional cost part is minor …
      

    Lucky you! Unless, that is, you were only referring to any additional cost with re-wiring the water heater, which is not likely to be necessary anyway. The difference in cost between charging storage heaters at offpeak rates and running direct heaters at either standard or peak rate will be significant.

     

    If you gave us a few more details of your situation, we might be able to make reasonable suggestions. I’ll see if I can find my checklist ...

     

    11 replies

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    Firedog
    Super User
    FiredogSuper User
    Super User
    January 28, 2025

    One thing I forgot in my last post: I see a 32A breaker labelled Shower. If you use an electric shower instead of one fed from the hot water tank, this is likely to be your single most expensive appliance. They’re often rated at  9-10 kW, so running that at peak E7 rate could prove very costly. A single 5-minute shower a day could cost £90 a year. In those circumstances, it would make economic sense to use hot water from the tank instead so long as there’s enough pressure. Then again, if you could tame yourselves only to use the electric shower during Economy 10 offpeak periods, £90 would shrink to £65.

    Just another factor to consider, I’m afraid.   

    Noel | I have no official status; I'm just a volunteer who comes here to help other customers. My gear: Aclara SGM 1416-B Electricity-only E7 meter; Chameleon IHD3-PPMID-AAA | It may look as if I know what I’m talking about, but don’t let that fool you. |
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