RTS meter without storage heaters

  • 14 June 2022
  • 6 replies


I used to be with SSE on an RTS tarrif. I live in Shetland which may have different tarrifs to the standard ones. I am now with Utility Warehouse and still have a 2-rate tarrif. I have just switched to an air source heat pump from storage heaters. The installers wired my heat pump into the A circuit on the consumer unit that takes its supply from the RTS meter because there was no room in the ‘standard rate’ consumer unit. This A circuit formerly ran power to panel heaters and the boost immersion, so presumably used ‘standard rate’ electricity. I guess the RTS meter does some adjustment to charge the correct rate. I only supply one meter reading from this meter and always have. The RTS meter is still ticking over though at about half of the rate it used to

My question is should I stick with this set up, until the end of support for RTS meters anyway? What are the pros and cons?


Thanks for any help


Best answer by M.isterW 15 June 2022, 18:58

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6 replies

Userlevel 7
Badge +1

Hey there @JohnU !

This might be a tricky one but we can try to advise. Could you show us some photos of the meters and your setup please?


Thanks @Blastoise186 . Here you go


Userlevel 7

Wow, quite a complicated one this one, @JohnU.


Sounds like your Heat Pump is wired up to take advantage of your current RTS dual rate plan. As this type of metering set-up isn’t currently supported by OVO, we’re fairly limited in terms of the tariff advice we’re able to offer here.


I’m wondering if you’ve been in touch with your current supplier to discuss your options? 


We do have plenty of Air-Source Heat Pump owners here who might be able to help too, @nealmurphy, @M.isterW, @hydrosam - any ideas?

Userlevel 6
Badge +3

That looks like a THTC set up as you have two meters. The black one for your heating and the small white one for everything else.

Do the appliances connected to the A circuits only come on when you press the red "boost" button or are those circuits live all the time?


Thanks @M.isterW . Yes it is THTC or a variant. We have migrated from storage heaters to an ASHP. The A circuit is alway on. It previously supplied back up panel heaters incorporated in the storage heater units.

I didn't expect this set up. I thought they would put in a new consumer unit for everything and I would change to a single tariff. The electrician came back and kind of explained what he'd done and said this arrangement would likely be cheaper. 

Does anyone know how the RTS meter costs the 'standard rate' electricity that goes to the A circuit? 

Userlevel 6
Badge +3

This website suggests that the "boost" circuit is on the cheaper rate -


But you need to check what your current tariff is to be certain.


In the near future the radio signal will be switched off but you are in a good position to move to a single meter. At that point you can either wire both consumer units into the new meter, fit a completely new consumer unit for everything or get a small CU for the heat pump and get rid of the old heating CU.