Hi guys,
First post, sorry if this isn’t the right category.
I just had Espaltherma integrated with Emoncms (through homeassistant). I think I’m collecting the correct data but I’m a bit unsure on how to analyse it.
Does this look normal?
Hi Jim,
Yes this does look like typical behaviour for the Daikin Altherma EDLA units (which I’m presuming you have). However, this is not good heat pump behaviour, your unit is constantly short-cycling, which is where it is starting and stopping short heating cycles multiple times per hour. Ideally for heat pumps you want them to run with low flow temperatures for a significant amount of time, whilst maintaining the desired temperature for the house. This can prove to be tricky to achieve with the Daikin Altherma units.
I suspect this is because you have your flow temperatures too low for the heat pump to maintain (< 30C). There’s a number of us here on this forum who have the Daikin installed and we’ve shared our knowledge and experience with this unit. I’d suggest searching for terms like ‘Daikin’, ‘Altherma’ and ‘EDLA’ on this forum and read through some of the threads (some of them are very long I’m afraid!).
One useful thread (that isn’t too long) is this one: Daikin 8kW family which contains a number of useful nuggest of information you could incorporate into your system settings, especially if it is one of the EDLA 8kW family members (that means either a 4kW, 6kW or 8kW unit).
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Hi Sam,
Thank you for such a detailed response.
Yes, I got a EDLA06E2V3 with underfloor heating on ground floor and radiators upstairs. Fully open system without separators or pumps. British Gas installed a tank with built in buffer, but it got repiped to serve as a volumiser after some pushback.
I will have a look at the thread you linked. Thanks for sharing this.
I’ve set my overshoot to 3c as you recommended in the post you linked. Ran a test this morning and it seems to have stopped the short-cycling.
Thank for your help @mortstar !
No problem at all, that is looking much better.
We have the same EDLA06E2V3 unit (you can find my system data here), having a larger overshoot value does help the system to achieve longer runs.
Although the system can be set to flow temperatures as low as 25C, a number of us have found the system can’t really modulate that low. For my system the lowest leaving water temperature I can target is 29C, lower than that and the system just cycles more trying to achieve a target temperature it can’t reach.
Another value that is worth experimenting with is the deltaT, default for underfloor or fancoil emitters is 5C, but you might want to try with 4 or 3C to see if that improves runtimes and COP. There’s conversation about that in this thread: Pushing for COP 5 on Daikin EDLA08E2V3
Obviously now isn’t great time for testing as it isn’t heating season. You’ll be able to experiment fully with these settings, as well as your WD Curve, once the temperatures drop.
Thank you for sharing your data with me. I don’t live too far away from you but my late 90s house is quite drafty.
The heating came on this night and I can see it’s now running for longer. I compared to your April data but seems like your heatpump doesn’t cut off like mine does?
Here’s my last 6 hours @mortstar
I think the light grey line is your target Leaving Water Temperature, is that correct?
I mentioned above that a lot of people on this forum that have a Daikin EDLA unit are not able to get them to consistently run at LWT below 30. You can see that during the hour long runs you are getting that the Flow and Return temperatures are steadily increasing, this continues until the overshoot value is breached.
My understanding is that your Flow and Return temps are increasing because your emitters (underfloor loops/radiatiors) are not able to transfer sufficient heat energy into your house to stay at a steady value. I’d suggest increasing your lowest LWT value on your weather curve to at least 30C and see if that helps the cycling you are experiencing.
You may well find that with this increased LWT, your heat pump will run without cycling at all. As a result your house may well increase in temperature, to the point where the heat pump stops because it is 1.5C above your desired room temperature (I’m assuming you are using the Madoka thermostat rather than pure weather dependency).
Personally I find the range that the Daikin will allow around the desired room temperature (I believe that is -0.5C to + 1.5C) is too broad and so I’ve created some automations within Home Assistant to switch the heat-pump on and off to keep the madoka measured room temperature within a range of -0.5C to 0.5C.