I suspect most of the regular posters here don't have much experience of electric combi boilers rather than gas boilers, including me... 

Do you know what make and model of boiler it is as a starter?

Certainly doesn't seem right the electric usage doesn't go down when the electric boiler is off.

I assume there is no gas to the property

Thanks,

Its a Thermaflow Eleectric Combi boiler.

So I have switched it off now at the mains and it is showing 6p per hour estimated cost but as soon as I turn it on at the mains the cost jumps to 2.30 even with the heating off. Seems way to expensive to me?

Electric boilers are notoriously expensive to run. They are a bit more efficient than a gas boiler (100% efficient instead of approx 90%) but electricity is more than 3 times the price of gas per kWh. So whatever someone else pays to heat a similar property with a modern gas boiler, you will pay 3 times as much.

Yeah I get that but at this rate I’d be looking at about £60 a day which seems extreme?

The high usage when the heating is off seems odd. Do you have a pre-heat setting on the boiler?

Have you tracked your half hourly electricity use over a few days? That would show if you're using a lot of electricity all the time or if there are peaks, when the boiler is working.

So having only had a brief look

https://thermaflowheating.co.uk/electric-boilers/

It looks to me like these have a thermal store of hot water for the heating and domestic water that ideally gets heated up primarily at off peak tariff i am assuming and topped up at other times? 

Is that your understanding or have i misunderstood? 

Is there a big tank somewhere?

If i am correct the tank of water may get heated up when the heating is not on.

It doesn't look like a simple electric boiler that simply heats water when needed or with just a small buffer. 

Do you know which of the models you have on the website? 

Have you actually run it for a whole day to see what happens? 

I’ve just googled Thermaflow Combi boilers and this is at the end of their list: somewhat out of date price per kWh 

With the heating on very low this is the figure I’m getting seems a lot? 

It might be worth giving the manufacturers a call and asking a bit about how the system works in terms of the tank pre heating the water for the central heating if that is how it works. There is a number on their website. 

Also worth bearing in mind with a gas boiler 7kWh an hour isn't unreasonable, the challenge is electricity is 3 times the price of gas.... And some of that is normal home electricity usage.

It is the difference between gas and electricity kWh that is really hitting you i suspect 

Yeah has gone up to 9kwh now so switching it off all together for the time being! 

I suspect it will drop once the house temperature is stable just like a gas boiler.

But having a chat with the manufacturer first before testing out for a few days feels like the right thing to do.

It isn't going to be cheap, but our old house won't be cheap to heat tonight with a gas boiler given the fall in temperature outside 

It is quite cold now outside... 

I’ve just looked at the so-called Instruction manual for one model and it’s appalling. Do you have a manual ? which model do you have ? Do you have an E7 off peak tariff you can get it run up to temp on ? Where do you live ?

As your system has a thermal store it's designed to be charged on cheap rate electricity, overnight. You should have a timer control that allows this (I found the manual online that shows how to do this). I'm prepared to bet that your system is trying to charge at the moment, hence the high electricity use. Once it's stored all the heat it will release it to the house as required.

By switching it off you're delaying the charge cycle so I would expect it to start again when you turn it back on.

I would find the manual and read up how to control the system. It can't be operated in the same way as a gas boiler. Are you on a tariff with cheap overnight electricity?

 I skim read the manual and stopped as it is not a quick read... Interestingly on another page on their website it says the best option is a single rate tariff.…

I wonder if it is charging or topping up the charge?

Is it clear how the charging and discharging works? I can't tell how clever or not it is.

Much more interesting than a lot of the customer queries we get

Ah. So it must keep running all throughout the day then Surely once it’s got a full tank it shouldn’t need 7-9 kW ?? That’s what my car charger uses !!

Interesting but expensive!

I've had a look at the rest of the manual and it isn't very good. Link here https://thermaflowheating.co.uk/downloads/

This is what the off peak timer control looks like.

I suspect you turn the actual central heating on off a bit like most people use their gas boiler and not like a heat pump.

 But exactly how the water tank works i really wasn't sure. There wasn't a simple diagram or description like you get with the sunamp heat battery which is the obvious comparison.

I think you would have to run it for a day to see what happens after speaking to the manufacturer. 

Interesting i haven't heard of this setup before with all the talk about thermal stores. 

Yep i gave up when skim read the manual. What it doesn't say is how a customer should setup and use the system in very simple terms unless i missed it. 

https://forums.moneysavingexpert.com/discussion/1673175/thermaflow

https://www.thisismoney.co.uk/money/bills/article-7966625/The-eco-boilers-cost-5K-year-green-energy-deal-gone-wrong.html

@Jeffus those links tell a tale of woe. What a shame as it’s got potential with all that wind power available in Scotland. In an ideal world the renewable power tariff would be peanuts and all those boilers could be working a treat. Is this the Total Heat Total Control I’ve seen Scottish customers talking about? now being phased out? Meanwhile @Chris0291 is going to have huge electricity bills. I hope that’s reflected in the rent?