Thank you OpenEnergyMonitor: Octopus Daikin ASHP monitoring

I just wanted to say thank you to Trystan and Glyn for their help.

I installed the monitoring on my heat pump a couple of weeks ago and started using the heating on Saturday for the first time since it was installed in June this year.

The monitoring is really good and has enabled me to get the settings dialled in really quickly.

I am sure I can do better but so far it is working really well and I am happy with the performance.

I have a Daikin 9kW Altherma 3 installed by Octopus Energy in June this year.

I struggle to see how I would have been able to understand what was going on without the OpenEnergy monitor.

It has been invaluable and I recommend it to any heat pump owner.

Thanks to the team at OpenEnergyMonitor, great work!


Thanks @matt-drummer that’s great to hear, much appreciated!


Thanks a lot for your kind feedback! It would be interesting to hear what settings you’ve changed and what the default commissioned setting were? This should help a lot of folk since there are quite a number of Octopus Daikin installation about to go into their first winter.


Hi Glyn,

It’s early days so I feel I need a bit more time to get on top of it confidently.

I maybe should make a separate thread about Octopus in due course but I need more data first I think.

The first problem I have is with the information available from the Daikin system, you just have no idea what is going on, it’s not very detailed and not really instant.

The controller is good and the app is ok for controlling the heating, but that is it, not useful for getting the most out of it in terms of efficiency.

I have our house quite warm, but I can afford it and like it, more expensive and less efficient than I could make it but I like it so far.

The heat loss survey from Octopus was pretty good, we only had to change two radiators and there were no additions but the temperature around the house is nicely balanced, slightly cooler upstairs and the living room is noticeably warmer than the rest of the downstairs, but it’s nice.

They had set it up with a constant flow temperature of 50c controlled by the Madoka room thermostat, not great.

I changed it to weather compensation initially with the upper limit controlled by the room thermostat.

The next day I put it on pure weather compensation which improved my COP but I encountered a problem when we went to bed, no way to set back the flow temperature as no scheduling was available, I would have to do it manually.

I need to look at this as maybe there is a setting that I have missed.

So on Sunday evening I put it back to room thermostat limited and I am actually happier with this.

I have a schedule set each day so from 05.00 it is 21c, then from 13.00 it goes to 22c and then from 18.00 it goes to 23c. At 21.00 it goes to 16c.

This ties in a bit with my Octopus Cosy tariff.

Then in the app I have gradually been reducing the flow temperature from the weather dependent curve to get the heat pump to run as long as possible.

I think you can see my data and I have just made it public.

I did the plumbing myself for the heat meter as I couldn’t get anybody to do it. It was an easy job, just access and placement was a little limited but I have over 30cm of straight run to the heat meter.

I don’t think I have any flow problems or air in the heat meter.

I don’t seem to have any short cycling?

I will keep knocking back the flow temperature from the weather dependent curve until I can’t reach the set room temperature.

This is my plan. I am now at minus 5c from the curve I set.

I need some more colder days to see how it works.

It was really cold on Saturday and Sunday and not the easing into heat pump use I was expecting!

But we were not cold and it didn’t costs a fortune so we are happy.

Sorry for the longish post but heat pumps are not easy!

If anybody has a Daikin Altherma 3 installed by Octopus that they need help with I am always around.


Did Octopus really do this?

Please do report it to MCS if they did. That is such absolute bodgery that even the MCS rules prohibit it!

It does make the unit use plenty more electricity though. Cynics might suggest that they would be very happy with that.


Oh dear, was WC really switched off? This must be a mistake, the other Octopus systems that we’re monitoring seem to have WC switched on e.g

I would give this feedback to Octopus.

Nice work, retrofitting heat meters can be tricky. This is often not quite enough space.

Great, that’s a good tactic to get the WC curve spot on.

Would you consider submitting your system to, so the data can be compared with others? This is anonymous, just use a generic location of the nearest city. You can login to the site using your account details.

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Hi Glyn,

I think I have made it public.

Is that not enough?

There was no weather dependent curve set. It was set up to run like a gas or oil boiler would.

I knew that was what they had done and that I would have to change it.

I think the end of the install was a bit of a rush.

You might notice that I am currently using wifi with your system.

I have wired internet in every room of the house but now some don’t work.

I found out why when I fitted the heat meter, the installers have put screws through the cables when they put the floor back down at the end of the install.

Not brilliant!

I have an Octopus auditor coming on Monday to inspect the installation. I’m not sure why as they already came and inspected three weeks after the install was complete.

If my data is not public, or not public enough please let me know.

I am happy to share all of my data.

I think I have shared everything now Glyn

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Great, thanks. I’ve just approved your system. It’s now on the public list.

It’s cool, there’s now 4x Octopus Energy Services installed systems on there. Performance seems to be inline with expectations with these systems which is good.


I think it was more down to me than them.

They knew I was quite engaged in the install and heat pumps generally.

I was just happy for them to go, it was an enjoyable experience but I had enough at the end.

They were happy to let me sort it out as was I.

I can’t recall and have no proof, I know it wasn’t on a weather dependent curve as I had to go into installer settings on Saturday to enable it.

Maybe not correct but I won’t be reporting anybody


There is one setting that Octopus have made that I don’t really understand the implications of.

My emitters are set as fan coils rather than radiators.

I have radiators, I don’t even know what fan coils are!

From reading the manual I understand it gives a faster response time set as fan coils rather than radiators.

This setting gives a target delta t of 8c (the difference between the flow and return temperatures) although that is not what I am seeing.

My flow and return temperatures are between 4c and 5c apart.

I am inclined to change to radiators and see what happens.

Does anybody have any ideas on why they did this and what the implications are?

For the last two and a half hours we have been heating to a room temperature of 23c, that is between 18.00 and 20.30.

It is 14c outside.

The COP for this period is 3.82.

I think that is OK.

The room temperature is higher than a lot of people would choose but it’s nice and warm when we get ready to sleep and it’s still pretty warm all night. It sets back to 16c at 21.00.

I suspect it’s more probably down to the contractors not wanting to be called back by a customer worried because the system is not “working properly”. We have a whole generation of people who got used to having gas boilers and “Hot” radiators. They now think that a radiator only works if its hot to the touch.

This is not helped by certain newspapers slagging off heat pumps at every turn and helping perpetuate the hot radiator fallacy. That it would be exactly the same if their old gas boiler had been fitted with weather compensation is seldom explained.

I have recently seen several gas boilers where weather compensation had not been enabled even though it was fitted. And one where it was turned OFF because of the warm radiators and it was an easy fix for “the problem”



That doesn’t make it not even the slightest bit compliant with the most minimal of instalaltions standards in the shape of MCS though.

It was either part of their training (that would be scandalous) or a general lack of competence (the days of Octopus paying 3rd party installers with some experience to fit heat pumps are over and they’re now sending out the apprentices that watched the 3rd parties fit the first lot / desperately trying to recruit “heat pump trainers” via LinkedIn etc)

Good that there’s OEM and consumers to snag the work / place their installations on a public facing league table to help up the game. :slight_smile:

  1. Becauase they don’t know what they’re doing and are slamming these in without first shelling out for some training

  2. Because they know what they’re doing and want you to use a bucketload of electricity

I’m inclined to believe it’s an accident rather than malice. Ask them? A handover manual of sorts is also part of the MCS requirements. :wink:

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My installers were really good and I have no complaints.

It was really hot at the time of installation and I really didn’t push or want any thorough instruction on how to set up the heat pump, I already had my own ideas and they knew I had done a lot of research.

Maybe I was a bit foolish and should have asked more but it was going to be a while before I needed the heating so I wanted them to leave asap on that Friday.

These installers are not interested in how much electricity we use and I don’t think the company is in the way you suggest.

My heat pump has no idea what it is pumping the water around. The difference between radiators and fan coils is only in the settings as far a s I can tell, mainly delta t between flow and return as far as I can see.

But maybe their experience is that this setting works best and that is why they do it.

I have someone from Octopus coming here on Monday so I will ask then.

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Great that you’re happy with the service at the price it was.

It does appear from here that whilst the pipes and wires are joined but they didn’t as far pushing the appropriate buttons or documenting why they were pushed; leaving that one as an exercise for the reader to work out.

To avoid tainting their responses you could ask “what should these settings be?” followed by “why mght the the setings be like this?” if they’re different.

In my experience that line of questioning avoids a tradesman - who you would otherwise have put on the spot by asking “why is the setting this” - from making something up to defend themselves rather than explaining things neutrally.

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Can anyone tell me which MCS requirements this and not setting fixed high temperature flow are, please? In a form MCS would understand. They seemed remarkably uncaring about a total lack of commissioning paperwork.

To avoid any confusion the way my system was set up was unique to me.

I don’t know for sure but I don’t think that Octopus would normally leave an install with a fixed flow rate.

We set a fixed flow rate to test the heating at a time when the outside temperature was over 30c and indoors was very hot. We just needed to run it and bleed the air, check for leaks and make sure that all of the radiators were working.

I told the installers that I would set up my own WD curve and associated settings, because I could and because I just wanted them to go. Not because they had done anything wrong, I had just had enough at that time.

I don’t think it is fair to assume that my installation and set up is in any way representative of how it would normally be done and left.

From my memory they wanted to to set up a WD curve but I said just leave it as I wanted to do it myself.

What I think I do have though is a heat pump that is too big. I have a 9kW Daikin Altherma 3 and one installer wanted to install a 14kW Daikin here!

I think I needed a 6 to 7 kW heat pump, so a 7kW Altherma 3 would have been right if I had to have Daikin. I would have preferred a Vaillant or Mitsubishi but I struggled to find an installer and Octopus were the only ones to come up with a quote. I tried Heat Geek installers and other local installers and never got anywhere

I might be glad of the one I have when it is really cold as I have read that the Daikins cannot give out their rated power at really low temperatures, how true that is I don’t know?

But my gut feeling right now is that it is too big. When I look at the electricity consumption it never goes below about 800 watts and so the heat output is really more than I need.

I wish I could get it to run for longer at a lower lower consumption but so far I can’t. It seems this is as low as it goes when heating.

It’s early days so maybe I can fine tune things better, and I don’t have a lot of experience yet.

Microgeneration Installation Standard: MIS 3005

“4.4.10 For all heat pumps, weather compensation should be set up and where
practical operable in such a way as to optimise efficiency with the maximum gradient
practicable. For example, where weather compensation would reduce the efficiency
of the system or be of no practical value, it will not be required to be made operable.
However, the MCS Contractor shall give specific reasons why this action has been
taken and the option retained to enable this at a later date if required. Examples may
be the use of fan convectors or other heat emitters exhibiting distinctly non-linear
heat outputs at varying temperatures, the lifestyle profile of the occupant and the
buildings responsiveness to the heating system.”

This MUST be configured UNLESS the installer has good reason which MUST be stated explicitly.

MCS fully understand but MCS fully don’t give a f**k about going anythign to ensure that the installations follow the requirements they set out provided that you’ve paid them their fees.