Heat pump only tariff - will it help us save?

[@keefsloan]

I can add some more hard data here from my perspective. I switched to Cosy on 13 January. Data for 13 Jan to 12 Feb is as follows: kWh usage - 1,774 Cosy Cost (including standing charge & VAT) - £545.80 Ovo (old supplier) comparison cost (@EPG 34p / kWh and including standing charge & VAT) - £620.60 Saving - £74 The heat pump pulled 969.6kWh during this period. As an EV owner, this also includes 166kWh put into the car during that period. So... Cheap? Nope. Cheaper (than Ovo)? Yep. Is gas cheaper? Yep. We are not on mains gas (or sewage). Have no neighbours (very detached). We're not sheltered (live in the country surrounded by fields).Totally electric. ASHP works well. When it's cold it costs more. I accept that. My historical energy usage for the past couple of years has been around the 13,500kWh mark (all electric). This is less than what Ofgem define as medium energy use - associated with 2-3 people in a 2-3 bedroom house. I live in a 5 bed house, no neighbours, windswept fields all around, with my wife and two teenage children. And I use LESS energy per year than an "average" medium energy user as defined above, including running an EV. So I'm doing what I can.

[@TomBray-LowCarbonLifestyle]

Hi Keef - thanks for sharing the data. What makes you say Gas would be cheaper? At 10.2p per kWh (price cap), and a 90% efficient boiler, you would have to have a COP of 3 to break even at price cap rates, for me even lower with the cost tariff, COP of 2.57. 13500 kWh for a large detached house with an EV doesn't seem bad at all. We used 5600 kWh last year for heating, light, power, cooking, hot water etc in our 3 bed terrace (just two of us living here), but no EV so that would add a bit! Are you happy with how the heat pump is performing? What do you reckon your COP is? What brand of heat pump do you have?

[@hyweljthomas]

Update: As of July 2024, Octopus are introducing a third cheap period on Cosy - from 10pm to midnight - and the cheap price is dropping to 11.48p. I think Cosy is an underrated tariff. We moved to it from Agile as it's much easier to manage for a family and dead easy to program if you have a battery - even a small one because you can top up three times a day. It also means that everyone knows the cheap times for running the dishwasher, washing machine etc. We managed to get the average kWh price on Agile down to about 14p, but that involved a lot of 'management' - Cosy just sets a figure and a time and we run with it. I'm confident that, with the battery, we can run 95% of the time at 11.48p. As you mentioned, a heat pump tends to work best when constantly on, but I understand you can tweak it to make use of the cheap periods. (I'll do that when I've figured out the most complicated manual I have ever seen...)

[@marcwhite7733]

Add a battery might be a move forward to cover the high cost tumes

[@TomBray-LowCarbonLifestyle]

That would help but I can’t find myself getting to the conclusion that a battery would be a good thing to do kzbin.info/www/bejne/fJmcm2ChfKl6qtE&si=EnSIkaIECMiOmarE

[@Hazellh]

Hi Tom, great video- we are considering switching to this tarrif as we have an Arotherm unit. I understand you very much can adjust for those off peak periods. Even with weather compensation and no room influence, the target temperature you set on the sensocomfort shifts the heat curve. If set at 20 degrees the temp compensations may result in say 700w being pulled, but if you put in a set back temperature to kick in at the off peak periods, say down to 16 degrees, it will shift that heat curve down alot, and drop the flow temps and associated wattage- no different to having the set back temperature overnight which a lot of us probably do already?

[@TomBray-LowCarbonLifestyle]

Hi Hazellh - ok, interesting, I have been a bit frustrated about the ambiguity of the controls, I haven't noticed the heat curve being shifted down at a set back temp, just the system switching off. That is really what I would want a variable heat curve, up during the cheap bits and down during more expensive bits. We aren't on Octopus Cost at the moment as over the summer I spotted how much cheaper Octopus Agile was, this may not last all year and we may switch back to Cost in the winter months... we'll see! I am sure I will keep tinkering with settings though Tom

[@joewentworth7856]

I have wiser thermostatic control so could just schedule for the high period to be 18 say and at cheap periods set room target for 21. If I turn off the hp on a day with 5 degrees outside the house temp drops about 1 degree in 4 hours if I turn it back on it takes about 3h to raise temp by 1 degree. This is due to having a heavy stone building. This smoothing would make this tariff quite appealing. Thanks

[@TomBray-LowCarbonLifestyle]

Hi Joe - yes that makes sense, it’s great to have some thermal mass to hold the heat. The small area of underfloor heating we have does this quite well. Tom

[@edwardpickering9006]

Octopus seem to be on it for sure... Unfortunately they won't even come and do a heat pump survey for my new build house as it has microbore pipes (not that it appears to matter so the Internet tells me...). Will be interesting to see if you switch back to Go in the Summer?

[@TomBray-LowCarbonLifestyle]

Thanks for the comment Edward, that is disappointing that Octopus won't visit. Have you tried other installers? I agree that from what I read micro-bore shouldn't stop an install but could limit efficiency, if you can't get enough flow rate to your radiators, you can't deliver as much heat at low temperatures. But you can still deliver some heat, and you could run a heat pump at higher temperatures and lose some efficiency... is your house well insulated? What temperature do you run your boiler at? I may look at switching, but I suspect I will stay with cosy for most of the summer, unless costs start getting much higher!

[@edwardpickering9006]

@@TomBray-LowCarbonLifestyle I'm actually waiting to see if we can get a Tepeo instead. It's a new build so loads of insulation, will have to wait and see...

[@seanmorris3730]

​@@edwardpickering9006 Hi Edward, I work in the heat pump industry and this is a great video that explains how to ensure a heat pump works efficiently with a heat pump kzbin.info/www/bejne/jZKuemCkeddmZ7c If you'd like some more information to improve your understanding let me know! Great video on what is hopefully the first of many heat pump tariffs @tom bray

[@stephenbrown4615]

Hi Edward, Octopus will now install heat pumps if your microbore is now at least 10mm diameter (but not 8mm) - they have just rolled this out, hope it helps!

[@edwardpickering9006]

@@stephenbrown4615 Thanks, despite them saying they'd get in touch if anything changes a while ago, not heard, but will have a second go!

[@pedal4health]

I'm interested in this tariff although currently with Ovo. I wonder how best to use it now I have ashp and solar. I turn up my thermostat during the afternoon and turn off the heating when the sun goes down. I do have to use electricity from the grid for my heating first thing in the morning as solar as not kicked in.

[@TomBray-LowCarbonLifestyle]

Hi Fred, sounds great being able to use your PV to power the heat pump and makes sense to try and use more power during daylight hours! I think Octopus have got some really interesting tariffs for people with solar and heat pumps, did you see the Octopus Flux tariff that they are bringing out too…? If you signed up through this link we’d both get £50 towards our bills - share.octopus.energy/azure-hero-218 Tom

[@sevastoskoumtzis5401]

This obviously has to do with the ratio of thermal inertia and insulation of a home. By including a larger thermal mass in the construction of a house , like brick walls and tile floors , the temperature swings would be less sudden. For an existing home, a baffer cylinder can work depending on the particular circumstances. In addition , as already commented by others, the reduction of the supplied temperature with the required controls setup, is also benefitual , although, the need for a forced convection unit (fan coil) will probably arise.

[@TomBray-LowCarbonLifestyle]

Hi Sevastos - thanks for commenting. Absolutely thermal mass is important in preventing swings, our house has a raised, elevated wooden floor (ground floor) so loses some heat there, but also quite a lot of mass in walls etc. I think the infiltration is the main reason we lose heat quickly. Do you mean buffer cylinder? We have a small buffer as part of our system. Yes adding a convector would help distribute heat more quickly. We are pretty happy with the set up, and happy to drop temperature slightly between 4-7pm, so it is working well!

[@PianoLearnerChannel]

do you have a slowcooker? this would help reduce the peak load at mealtimes

[@TomBray-LowCarbonLifestyle]

We don’t but that’s a helpful suggestion! Would mean I have to plan dinner in advance of ‘what do we fancy cooking tonight’ each night at 645/7pm!

[@joewentworth7856]

Finance aside , this is probably a greener way to run you hp. I have been using a co2 intensity app..that gives the expected co2 per kwh. It varies wildly from 100g to 350g per kwh. Dependinf on time of day. Generally the cheap times are also low carbon.. and the opposite at peak times .

[@TomBray-LowCarbonLifestyle]

Absolutely! The marginal kWh tends to be the dirtiest, and most expensive!

[@MrButuz]

Can you run your heatpump at a hotter setting, so that it's making the most of the cheaper rates and then keep it completely off for the three hours? I.e overwarm the house slightly particularly in the 4pm price dip so that the heat lasts for 3 hours? Either way I can't see these heatpumps being any cheaper to run than a 35kw gas combi boiler to be honest. (unless you have bucket loads of cheap tarrifs and bucket loads of solar panels and bucket loads of battery storage but then your talking £20-30k to try and reduce your gas bill so it doesn't make any sense to me in the short term (short term i.e 5 years whilst we have to face these silly high energy prices compared to the rest of the world...)

[@TomBray-LowCarbonLifestyle]

Hi Mr Butuz - thanks for the comment... yes could preheat the house a bit more. I already do slightly, but I am a bit of a energy scrooge so don't want us to get too hot...! Why can't heat pumps be cheaper than a gas boiler? On the current price cap rates (10.2p per kWh gas, 34p per kWh electricity) you would need a COP of 3 to be cheaper than a 90% efficient boiler. Many systems will have a COP much higher than that. Ours is about the same so would be breaking even at the price cap, and saving on this cosy tariff. We don't have any solar or battery storage but cheaper to run per kWh of heat. Not cheaper enough to pay back the installation costs, but we should be valuing the big reduction in emissions too. I have signed up to a Ripple energy scheme, that should reduce bills by around 5p per kWh too... so would be a big saving compared to gas. And one day, we are likely to get solar, probably not a battery as one day will have an EV parked outside... but we aren't quite there yet. Cheers! Tom

[@rupertmiller4718]

For many people though the real comparison, especially in an older less well insulated house, is how does this compare to gas? If the aim of government was to drive down the cost of electricity and weanboth the energy companies and consumers off gas it wouldn't really matter in the long term. However, this government doesn't really seem to have a strategy beyond "good soundbites"

[@TomBray-LowCarbonLifestyle]

Hi Rupert - absolutely, a comparison with gas is a worthwhile one - I did this video to summarise at the price cap rates what the impact would be... kzbin.info/www/bejne/n5a5daaJlL6Cnbc I think a fairly normal system will break even with a gas boiler, and certainly in my home with slightly improved efficiency, and with a time of use tariff like the Cosy tariff we are saving a great deal. And then if couple with solar panels, or a subscription to someone like Ripple energy, costs could be even lower! Without commenting on our government (lack of) strategy...!

[@karma3101]

My fear is, once the majority are totally dependent on electricity and we all have smart meters fitted, how long will it be before the energy companies/government start to dictate what appliances we can use and when we can use them?

[@TomBray-LowCarbonLifestyle]

Hi Karma3101, thanks for the comment, I am not sure I understand, we are depended on electricity already? And energy companies or government could have shut off supply of electricity or gas at any stage before today but haven't... why would they start to do that with smart meters or heat pumps? Smart meters help the energy system work efficiently, and help companies like Octopus offer innovative tariffs to incentivise moving electricity demand away from certain times. We live in a democracy - if a government does something we don't like, we can vote them out. Tom

[@battsonbikes1919]

That is comming

[@karma3101]

As successive governments close down our fossil fuelled power stations and rely more and more on wind and solar, along with forcing people to switch to all electric space and water heating, not forgetting EV charging. At some point demand will out strip supply which will inevitably result in power shortages. What better device than a smart meter could be used to monitor and control people's usage?​@@TomBray-LowCarbonLifestyle

[@LynneWilliams-yy1dk]

What temperature do you keep you home?

[@TomBray-LowCarbonLifestyle]

Hi Lynne - we tend to aim for 19°C although this varies throughout the house (old, draughty house!) so when our living room is ~20°C our hall way could be 17.5°C.

[@offgridwanabe]

Maybe a sand battery wouldn't have to be too big to last 3 hours.