Cosy Octopus for Heat Pump Owners

FlossieFlump

I looked up Octopus heat pump tariff and it is no good for anyone with a heat pump. Its more suited to the old economy 7 system. 

I have a Daikin HP wet heat pump system, it's 10yrs old this year. To get the most out of a heat pump it needs to be on 24/7 you cannot turn it on and off as Octopus suggest because it uses more electricity each time you switch it on,  it also doesn't heat the radiators as hot as traditional gas or oil boilers which and so takes longer to heat your home because you have to wait a long time for the overall home temp to get to a comfortable temperature. 

My HP is on 24/7, it's never turned off. It keeps my bungalow at a steady 18C all year round apart from Summer when I turn it down to 12C because I don't need the heating on so it won't kick in but it does still heat the hot water for the bathroom and kitchen. 

My home is all electric there's no gas here or oil. And mid winter this year with the heating ticking over at 18C plus usual domestic use such as cooking, laundry etc my daily usage is around £4 a day sometimes £5 a day if I've used the washing machine and drier. In the summer I anticipate to use around £2 a day if we get a good summer. 

If I changed to Octopus' HP tariff I'd probably pay treble that or more. I'm with EDF on a standard tariff. 

I contacted Octopus and asked why they are pushing their HP tariff when it clearly isn't suitable for HP systems and explained to them how you should use HP's and they just said their people who work out the tariffs know what they're doing and weren't interested in what I had to say. The problem is their people who work out the tariffs obviously have no idea about how to get the best out of their HP system. 

But when I thought about their E7 style tariff for HP's I realised it's not for the consumer's benefit at all, it's for theirs. Because switching. your HP on and off twice a day you will use more electricity so you will be paying them more money than if you left your HP on 24/7.

So do be aware that although Octopus may be competitive with normal regular systems they are not at all competitive for anyone with a HP. 

Reed_Richards

I don't for one minute believe that you have to run a heat pump 24/7.  If you have underfloor heating embedded in concrete then it will be very slow to heat up and cool down so UFH you possibly do have to run 24/7 but that's because of the type of heating you are using, not because of the source of your heat.

I set back the temperature of my house overnight because I like it cooler overnight.  Unless it's very cold outside this causes my heat pump to be completely off for six hours.  When it comes back on the house temperature is cooler so the temperature difference between outside and inside is less which means that the heat pump will run more efficiently whilst it is warming up the house.

That said, I do agree that the Cosy Octopus tariff doesn't seem to be at all well-matched to the way you would want to run a heat pump.  So we do agree on the central point.   

mickyduck55

I have only had my ASHP since January and am on Cosy which seems to work for me as I have batteries that I can charge up in the less expensive tariff windows.  The advantage of cosy over flux in the cooler months are the two lower rate periods rather than the one on flux.  I will probably change back to flux soon as I am a net exporter of electricity in the sunnier months. 

Patrol

I have had a GSHP since 2007 and was on default tariff's for many years. Added solar without battery in 2021, moved with Bulb to Octopus (a tad frustrating as I wanted to switch over to Agile just as Bulb went into administration but could not do so for several months)

Octopus have a page that suggests what works best (link https://octopus.energy/octopus-smart-tariffs/), and Cosy is returned for "Heat Pump" or "Heat Pump and Solar"

I find Agile plus Outgoing Fixed works for me at present. Between 4-7pm I've disabled hot water and reduced heating by 1.5c (recommended maximum underfloor heating reduction for my heat pump model). If Agile peaks were more frequent, longer, or at random times it wouldn't work for me

I have looked at Cosy a few times and can't see how it works for heat pumps. Trying to maximise use in two troughs in addition to avoiding the peak doesn't feel like a good match

koru

I came across a Which? magazine article on ASHPs. https://www.which.co.uk/reviews/ground-and-air-source-heat-pumps/article/ground-and-air-source-heat-pumps/air-source-heat-pump-costs-and-savings-akySY6N5Y6Dd

This includes a chart showing a comparison of running costs for gas and ASHP and how this varies with the SCOP of the ASHP and with the electric tariff. 



On the face of it, it suggests that on the Cosy/Agile/OVO tariffs it will be cheaper to run an ASHP than a gas boiler even with poor SCOPs.

But a few caveats are in order:

It does not explain what assumptions underlie the Cosy and Agile tariff curves. Judging by the ratio of the annual running costs in comparison with the OVO tariff, which is 15p per kWh all the time, they appear to be assuming that the average price on Agile would be about 17p and on Cozy, about 20p. This suggests they have assumed steady operation 24 hours a day. By judiciously skipping a few peak hours, the average price on these tariffs could be way lower on these tariffs. (Though this might worsen the SCOP.)

Of course, prices vary on Agile, so it could become even cheaper or more expensive.

I imagine they are not taking into account the effect of the choice of tariff on the electric used by the rest of the house (cooker, washer, tumble drier, etc). If you have an ASHP, it is going to be the majority of your electric usage, but non-ASHP is not negligible. I estimate that if I switch to an ASHP my electric usage will increase from 2500 kWh per year to 7000-8000 kWh. Cosy applies to all your electric usage and it is 45% more expensive than the price cap tariff between 4-8pm each day, so if you can't time shift your cooking, clothes washing, ironing etc your Cozy savings on the heating will be partially eroded by paying over the odds for this other peak-time electric use. With OVO, the 15p rate only applies to the ASHP, so you are paying price cap rates on your other electric use. Whether this is cheaper or more expensive than Agile depends on how much of your non-ASHP electric usage is at peak price times of day (especially 4-7pm).

Arguably, a fairer way to compare gas with Agile would have been to use a gas tariff that is similarly variable, ie, the Octopus gas tracker prices, which are usually lower than price cap. Tracker prices vary over time, but over the last year they have been about a third cheaper, so if you used that rate the green line would move down to below £600.

Netexporter

It's quite comforting that an ASHP beats gas in almost any circumstances, provided you pick a suitable tariff. I do wonder how many people might be so underinformed to be using the SVT with a heat pump. I was shocked to learn that 80% of people are still on the SVT.

wrf12345

You then have to find a heat pump that works best with cheapest tariff, which in turn probably means you need a super-insulated home (ie you run the heat pump only during time periods when electric is cheap and keep the heat in the house). All good fun,

MP1995

wrf12345 said:

You then have to find a heat pump that works best with cheapest tariff, which in turn probably means you need a super-insulated home (ie you run the heat pump only during time periods when electric is cheap and keep the heat in the house). All good fun,

6 hours of cheap heating won't be enough for a heat pump on many houses except very high EPC A near passive haus status.

The tariff may come into its own as tracker gets close from July to SVT and maybe breaches it.

For us with our heat pump even over winter Agile out stripped all other Octopus offerings and that's without solar or batteries or an EV

Magnitio

Netexporter said:

It's quite comforting that an ASHP beats gas in almost any circumstances, provided you pick a suitable tariff. I do wonder how many people might be so underinformed to be using the SVT with a heat pump. I was shocked to learn that 80% of people are still on the SVT.

It also depends onthe gas tariff that you are using as a comparison. The Octopus Tracker gas tariff has been around 4-4.5p/kWh for quite some time. Another complication with choosing a suitable tariff is if you have an EV that requires regular charging, although during the non-heating months I guess you could do most of your DHW heating at cheap rate.

The majority of people don't realise that there are different tariffs that they could make use of, or find it all too confusing.