My new home has a Total Heating Total Control (THTC) system. How do they work?

That’s because they don’t want you to find it that easily. I just told a few of their call centre advisors that I’m a forum volunteer here and boom! Instant answers. I don’t really know why it works so well either… It just does for some reason.

Oh yeah, I just realised we never answered part of your question!

The answer to Does Scotland get 8.5 hours of Economy 7 is Yes. Technically, it may be called White Meter up there but it’s close enough (what’s in a name comes to mind!). Your hours for the South of Scotland is 8.5 but it’s the standard 7 in North of Scotland. For the former, the times are 11:00PM to 7:30AM, for the latter it’s Midnight to 7AM

We’ve got that covered at 

and also the DNO list at 

Thank you @Tim_OVO and @Blastoise186,

So the south gets more off-peak time than the north? That makes absolutely no sense! Then again, the past week has taught me that very little regarding electric supply is supposed to make sense to mere mortals like myself...

So what’s been happening recently?

Well, nothing much really…

I had the scarf advisor round today, apart from some advice about loft insulation and talking to octopus to get the meters changed I’m too energy efficient for him!

Its about £4.40 to have the living room storage heater do an overnight charge for 7AM-8PM of heat at 21C. Going up to about £5.17 tomorrow.

There’s no point going to SSE about changing the meters as I’ve been told they have a rigid schedule which they will stick to for changing people over. So I’ll be sticking with octopus for a long time I think. Their great customer service is a real selling point! (Take note SSE, nobody likes talking to somebody in India about their energy usage in the UK...)

I’ll have to do some calculations about getting octopus to switch the meteres over, the scarf advisor suggested E7 or E10, but seeing as I use most of my energy during the day, I’ll be seeing if its worth switching to a single rate smart meter.

I might just be worth going to the single rate as having a second electric meter will cost £186 ALONE in the standing charge, I barely use the heating so I’ll have to see.

@Blastoise186, Re; LMAs. SSEN were absolutely useless, I either get sent in a circle of people to contact, told that I can have my load increased or to talk to my supplier! Looks like it’ll be yet another ‘Octopus saves the day’ scenario...

Ongoing nightmare of extortionate bills in a relative’s rented studio flat with ancient electric storage heaters and a 2 meter system. One rate is Standard Evergreen, the other THTC (Total Heating Total Control). Supplier is SSE/OVO. Property is in North East Scotland.

The THTC rate is supposedly a cheaper rate for off peak energy delivered to hot water heater and radiators overnight but I debate whether the radio control switch is still being provided for this. Bills are averaging £300 a month (paid quarterly from meter readings, not estimates) which is ridiculous given the size of the flat. He his afraid to have storage heaters on now and uses a plug in panel heater with thermostat in one room only most of the time.

I arranged to have a timer switch on the boost element on the water tank and switched off the main element to try and save some energy. Thus, the top of the tank is heated for a couple of hours a day to allow for a shower/washing up. Washing machine, oven, hob, tumble drier are not used due to disability. My relative has been forced to have 2 of the old storage heaters on during the very cold spell we’ve had recently but these heaters have no control panels or thermostat - they are either on or off.  The largest of the storage heaters has input/output controls but it remains switched off at the wall as the dials have melted (oh the joys of private renting).

My question is, could we have the old storage heaters disconnected and have the THTC meter removed, leaving one meter/one rate? What would this involve? We just can’t fathom where the energy is going and I can’t help but be suspicious of the 2 meter/rate setup. 

Thanks for reading this far! Any advice appreciated.

Sounds terrible @THTCnightmare 

I used to have huge electricity bills as my hot water was only heated with an immersion and I had no way of knowing how hot the water was. As it’s probably the heaviest use of electricity in the flat I’d try reducing the time it’s on even further. It’ll be like having the kettle on for two hours solid. If it’s as ancient as it sounds the thermostat probably isn’t switching it off once it comes to temp.

It may be worth reading through some or all of this thread:

Hey @THTCnightmare,

That sounds like a really complex and frustrating situation to be in.

I’d advise contacting your previous supplier, they may be able to book in a Site Survey for an engineer to come and asses the situation first.

We do have some topics on THTC which may have some helpful information- @juliamc has already shared one:

I have just moved into a property in N of Scotland on THTC with SSE/OVO. 

Find it all v confusing and v expensive. Heating is from radiators with outdoor air source heat pump. No storage heaters here which seems to be what THTC is set up for? Costing a fortune! 2 working adults so out all day, using woodburner in the evenings but got a bill for £662 for our first 6 weeks here! And no, not an estimated one. Seem we are on a super expensive traffic and can't switch from it. When I phoned I was told they dont deal with "exotic" meters. What to do?

Can you tell us more about your heat pump ? The best way to run it is to keep it running 24/7 which seems counterintuitive if you’re out all day. You just need to balance the heat loss of the building. Is it set up with weather compensation ? 

In truth I dont a lot about this air source heat pump beyond that it pulls cold air in, then uses electric (on the higher of the 2 tarriffs) to convert to heat. It is on 24hrs, but I've lowered the temperature control thermostat to 17.5 daytime and 10 degrees overnight so it doesn't trigger the heating. We've been relying on the wood burner for heat.

I called Ovo again and spoke to someone in the "exotic" meters team. My understanding was that the dual meters needed replaced to a single one so I could switch tariff. But he said that are not in a position  to change the meters, and that if I supply a read he would convert me to a single tarrif. I was somewhat sceptical of this, worried it would end up costing even more. He reassured me it "should" be less expensive but couldn't on the phone call supply actual costs to me. And that was after 37 minutes on hold to speak to someone.

Is there anyone else out there on these THTC meters, particularly anyone with radiators rather than the storage heaters this was designed for?