There is one Cosy 6 on the public dashboard so far, data from heatpump integration (not independently metered): HeatpumpMonitor.org
Edit: and it already looks too big for the property
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Iām afraid I disagree here. I feel that Octopus were in more of a listening and learning mode back when they installed our Daikin heat pump in March 2023, I believe their approach has changed. Based on many interactions on this forum with other members who have the larger 9/11/16kW Daikin Altherma units, and conversations with people Iāve spoken to locally, they seem to have become increasingly intransigent.
They now consistently refuse to lower their 50C @ -3C design temperature, even when a lower temperature is demonstrably more appropriate for the property. This is leading them to install the larger Daikin unit, which cannot modulate to a lower energy consumption and has been described by various members of this forum as āa beastā or āa volcanoā. In several cases, they have ended up replacing these larger heat pumps with the smaller Daikin unit after it became clear they were oversized. This involves significant costs for Octopus, and a lot of inconvenience for those who have to fight their corner for a system replacement.
Itās concerning because Octopus has access to excellent data from installations like mine, where they installed OEM monitoring equipment. This data should clearly show the performance of different sized units in various conditions. Despite this evidence, it seems they are sticking with a ācookie-cutterā approach to system design, which definitely doesnāt result in the best outcome for their customers.
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Party they are advoiding complaints when a property does not heat up quickly enough from cold. We do not represent how many people use heatpumps, also likely our properties have better installed insulation and higher airtightness then is common.
It is also less likely we are ill old people who need a higher internal temperature then us and have relatives who will create bad PR for heatpumps.
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I cancelled my Octopus Daikin installation last year because they insisted on installing an 8kw unit. Their own heat survey came back at under 6kw. Heat Geek came in at 4.4kw, Michael de Podestaās rule of thumb at 3.5kw and another on-line calculator was 4.9kw. Iām pretty sure the 8kw unit would be well oversized.
When I questioned this, I was told that the heat pump sizing also has to be based on the last EPC and ācanāt take into account of additional energy saving measuresā.
Based on the Octopus survey I upgraded a couple of radiators myself. Over the last few weeks Iāve been running my GAS boiler with a flow temperature set to 46Ā° to simulate having a heat pump and that has kept us toasty warm over the recent cold spells.
I download my half hour GAS and electricity usage from Octopus and this month (January 2025) the maximum daily average for GAS was 4.4kw. including hot water. I appreciate this is not a 100% accurate representation of a heat pump operating but it does reinforce my believe that an 8kw pump is overkill. The other issue I had with Octopus was trying to get technical questions answered. Most times outside the cold winter days the heat requirement is considerably less and I wanted to know at what level the 8kw Daikin unit would modulate down to rather than cycling on/off. And then there are additional costs associated with the install that arenāt always apparent. The Daikin hot water tank wonāt fit in my airing cupboard. Iāll have to pull it down and rebuild a bigger one. My Aqualiser shower pump needs to be replaced (currently gravity fed) - Ā£390. Then there is a garden wall that has to be removed and path widened. There seems to be quite a disparity in quotes from Octopus. it appears that some people can get an install for less than Ā£2,000 with a dozen radiators being replaced. Even with no radiator replacements Iāve been quoted Ā£3,000.
Daikin donāt actually make a smaller heat pump.
The 4/6/8 kW models are all the same, just software limited to restrict the maximum output.
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So what is the minimum output when modulated at lowest level?
2,000W, maybe even down to 1,500W but efficiency suffers.
An 8kW Daikin can go down to 300W of electrical input, a little less at times.
Have a look at the data.
The give away is that they all produce 8kW or more when running DHW.
They all have the same compressor and circulation pump.
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Thanks Mathew, Iāve looked all over to find a data sheet that gives the lowest level of power input without success. Can you suggest where I might find it. Either way Iām re-assured that this unit will do the job and have re-contacted Octopus.
Look here, plenty to choose from, real life examples, not what the manufacturer thinks they might do!
The whole point of the site really!
Hi Iain,
I did the same without any success whatsoever. I also pressed Octopus to find out from Daikin, who were unable to provide the information to Octopus.
I think other manufacurers are equally coy about minimum input and output figures. I have no idea why this should be such closely guarded information.
But as @matt-drummer says, all of us on heatpumpmonitor.org contribute real-world comparable figures for energy consumption of many models of HP.
Great website. I noticed several installations by Octopus. Is the kit fitted to show this data included in a standard Octopus installation?
No.
They did it on 50 installations with heat and electricity meters., not mine though.
Most people use (I donāt) a device which takes data straight from the heat pump, not necessarily accurate but good enough for fine tuning.
To see those you need to tick other metering and heat pump integration, the initial page only shows you those with certified metering. There are a lot of Octopus Daikin installs.
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Our Daikin EDLA09 draws 1000W minimum. Maybe 950W for short periods after the initial ~3kW blast, but it trends upwards over time.
Output of course depends on COP, you could have 3kW or 5kW for the same power input depending on the rest of the system.
what size HP is your Daikin - Does EDLA09 mean its a 9kw unit?
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Thatās right. Those 2 digits give the nominal KW outputs for all the EDLA models.
Yes - but itās very much nominal, for example the 9kW being the smaller unit in the range often gives ~12kW according to my monitoring.
Nice quick update on this one.
Octopus wonāt install the 8KW unit saying that it isnāt suitable for my current HL (7.7KW based on their estimates). I would need to get my heat loss down to below 7kw before they will go ahead and install the system.
They noted that my āwindows are too bigā. Unsure what that means, and suggested I get new windows (I already have double glazing all round?). Apparently event that wonāt reduce my HL enough, so they looked at removing the rads from my kitchen which will bring it down to about 7kw and have ākicker heatersā instead, which are electric heaters which sit under the cupboards to heat the kitchen. Both of these options seem insane to me.
Octopus do understand why I want the 8kw unit, and are aware of the the issues with the minimum operating values of the 9kw unit. They will accept a third party HL estimate though, and if the numbers work, they will fit the 8KW unit for me.
After reading a thread on here last night about MSCs HL calculations, it sounds like the HL reports are always going to be much higher than required, so a third party doing another report will likely produce the same figures. This isnāt an issue with the installers, but with MSCs guidelines and everyone adding āa little bit on topā for those just in case moments. I expect they fear if they install the wrong unit, they will be on the hook for the 7.5k grant.
This all leaves me in difficult position. Do I go with another supplier and hope they agree that the HL is good enough to install a 8KW system or do I suck it up with Octopus, get them to install the 9KW unit and then kick up a fuss with real HL data till they install the 8kw unit.
The latter I really do not want to do. What I am fortunate for is someone pointed me here before I blindly got the 9KW unit installedā¦
As a check you can use heatpunk to do a heat lost calculation, . Itās a free online webpage and looks very good.
As an extreme can you ask octopus to make a room ,ānon heatedā which would drop the total HL number
Only issue could be if the 8kw is under powered for the house on a couple of days a year when we have true cold days at or below calculated temp you may need additional heating
I get the impression that Octopus have a warehouse full of the 9kW units to get rid of!
The 9kW isnāt the end of the world. You have a decent amount of radiator area at 8.5kW (and Iām assuming this is at the rated design temp of 50C). This at least means that provided you donāt go below ~35C flow, youāll be able to emit enough heat to get a COP of 4.
Certainly donāt assume Octopus will swap your heat pump just for the asking - at least thatās not been my experience.
Do you have daily figures for gas consumption for some cold days, say around Jan 11th? Divide by 24 to get average heating power. This can give a good estimate for how much heat is required, though youāll have to take into account the efficiency of the gas boiler (maybe 70-80%?) and the wood burner. Octopus would be hard pressed to argue against historical consumption.
Better still if you can find temperature records for those same days, and plot them on a graph.
Also, give Trystanās new Simple heat loss tool a try, though it can only be a rough estimate.