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Octopus Cosy Heat Pump Owners & Discussion Thread

AndrewJ · 2025-10-23T11:37:06Z

I'd like to discuss how you find it, how you run it and so on.

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AndrewJ

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Topic starter 18/12/2025 5:32 pm

Posted by: @harrisonc

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@andrewj Forgot that bit as I haven't had to do it in a while. Trying to figure out the Manufacturer password (or a bypass), as Engineer password is rather easy but doesn't offer much.

I can't figure that one out either. The person I spoke to today had me log on and slipped in the password "octopusenergy" all lowercase but obviously what was needed was the passkey on the hub itself. You could try that perhaps??

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HarrisonC

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18/12/2025 6:20 pm

@andrewj So "octopusenergy" is the password for one of the pages, but there is a separate Manufacturer password for two other pages. I did manage to get the code to render the two pages without validation and there are some manual controls and ability to reset AWS (assuming link back to AWS storage buckets) and some other settings, but I wouldn't want to mess around with that anyways.

Interesting that someone posted on the FB group just now about a new smart controls feature for the heat pump.

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AndrewJ

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Topic starter 18/12/2025 6:51 pm

@harrisonc I've not seen that, it's not coming up on my feed.

I definitely think you want to be careful playing around with the interface areas that you aren't supposed to be in! It's interesting to see data or control points though.

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HarrisonC

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18/12/2025 7:03 pm

@andrewj It's in the comments on the PCB post from yesterday. Here is the screenshot. The user is on the Cosy tariff as well, so it might be that it priorities heating in the tariff cheap windows.

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AndrewJ

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Topic starter 18/12/2025 7:19 pm

@harrisonc The comment related to not being able to control the thermostat but can change the WC values is interesting. Does that point to a new feature to allow you to run it purely on WC and flow temperature with some temp modulation. I.e. using the Primary Pod as an internal temp sensor rather than a thermostat?? That would be useful.

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HarrisonC

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18/12/2025 8:24 pm

@andrewj Yeh, I am not sure. I assume though it is to allow the heat pump to boost over the normal set temperature in the off-peak periods and then ride through the peak periods before turning on again.

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AndrewJ

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Topic starter 18/12/2025 9:05 pm

@harrisonc I guess lots of possibilities. The Cosy tariff has fixed slots but Octopus Agile is highly variable; it could also be to allow Octopus to control the heat pump on a special tariff that allows it to boost and turn off according to spot rates. I’m hoping for non-thermostatic control though 😀

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HarrisonC

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18/12/2025 11:01 pm

@andrewj Seeing they deleted both threads with the pictures on the group... maybe wasn't meant to be public yet.

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AndrewJ

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Topic starter 19/12/2025 10:07 am

@harrisonc wow. That’s going to get the rumour mill grinding!

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KevH

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19/12/2025 5:39 pm

Posted by: @harrisonc

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@kevh Yes, so effectively over 8 degC outdoor temp it will always have a flow of 30 degC and below -15 degC outdoor temp it will have a flow of 50 degC, but in between the curve will be a shallower as 1 degC outdoor temp change will equate to 0.87 degC flow temp change.

To do this you have to go into installer mode in the Cosy Hub by pressing the button on top of the hub for 10 seconds till the light is solid blue. Then on a device (suggest a computer, rather than a mobile) connect to the OCTOCOSY (think this is the name) WiFi network that the hub is now broadcasting. Navigate to IP address 192.168.1.1 in a web browser and then you can adjust it under the Setpoints tab. There is a publicly available installer guide here that explains it in more detail, although is slightly out of date.

Ah, yes, so the effect is to shift the WCC towards the cold end by about 5c, so that at -10c OAT your FT is around 46c? Sounds interesting.

As @andrewj says however, the Cosys cannot modulate below a FT of 36c, which restricts the usable range of FTs available via the WCC to 36c to 50c. So if I shift the cold end of the WCC to a FT of 50c @ -15c OAT and leave the warm end at a FT of 36c @ +12c OAT, then the FT at an OAT of -10c falls to about 48c? And the curve becomes flatter. That is a potentially attractive way of overcoming the restrictive 50c minimum cold weather FT. I might trial this, but maybe after Christmas when the OAT is expected to fall slightly and the wife isn't looking.

If I am talking b*ll*cks you will no doubt tell me.

Many thanks for the info on accessing the Cosy Hub.

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AndrewJ

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Topic starter 19/12/2025 6:04 pm

@kevh It's something I'm trialling at the moment - I've set the Cold Weather Max Flow temp to 50c at -10c and left the Warm Weather Flow Temp at 36c. You can adjust the warm weather end below 35c, it has the effect of steepening the curve but the 35c minimum modulation (of the Cosy 9, don't know about Cosy 6) cuts in at a lower temp. The attached image is my attempt to map the WC curve from -10c to +12c at different settings. It's probably mostly right as the curve is linear. I was advised not to drop the warm weather end below 36c but it's not really clear to me what actually happens to the Cosy if you do so and I don't have a means to measure data points not shown in the app, which is extremely limited.