Daikin 8kW family

Hardware Heatpump
1

My new heat pump is going OK but I am a bit disappointed in one aspect.

I just doesn’t want to run at times and I don’t understand why.

I have tried everything I learnt from my multitude of issues with the 9kW Daikin but it is hit and miss.

I just want a heat pump I can turn on and let it run, do DHW and then resume heating again.

I don’t really expect any answers but maybe somebody sees something I can’t.

I haven’t changed any settings but I just don’t understand the issue.

Here is the last couple of days, it runs for 44 hours with no issues.

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All good until it tries to get going again after the DHW run, I just don’t get what is stopping it running.

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I could run at lower flow temperatures if I could get it running in the first place.

The start up is quite aggressive with a high flow rate.

I have tried my old tricks of limiting the flow rate and I have run with a tighter dT. But limiting the flow rate didn’t really work and it applies all of the time so is of no help really.

My heating system is the same but this heat pump seems to struggle with a constant flow temperature and heat output.

When running at a dT of 3c it really seems to struggle with finding a flow rate to maintain the requested dT.

To me it looks like everything is based on the return temperature, you set a flow of 29c and it forgets this and just concentrates on a return of 26c.

None of it really works.

I have tried using the Madoka and a weather curve but the result is the same.

Maybe just leave it alone and let it sort itself out? The really short cycles bother me, not what I am used to but I see most of the others from this family of heat pumps doing the same.

I called Daikin today but they don’t even understand what I am talking about.

Also, the overshoot is fixed at only 1c, I cannot start at a higher flow temperature and turn it down unless I am really lucky and watch it at just the right time.

Turning it down when it is overshooting the requested flow temperature just results in it turning off and restarting with all the problems listed above.

I don’t understand why it starts with such a high flow rate, it produces too much heat at the low flow temperatures.

It could be really good but I can’t spend my whole life trying to coax a heat pump to heat my house every time it stops to do DHW.

I don’t understand why it is stopping after only three or four minutes?

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2

Have you tried overshoot of 3 or 4? Mine runs much better it modulates down in mild weather rather than stopping unnecessarily.

Have you got a volumiser on the flow that would get heated up during DHW and cause the flow temps to be too high after a DHW run?

3

Hi,

There is no option for a higher overshoot than 1c with these heat pumps, it is set at 1c only.

I have a volumiser but I don’t think that is an issue.

My return temperatures are good, nothing that should stop the heat pump running, whatever I do makes no difference and I take steps to minimise the return.

Flow now at 32c, still no joy!

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Now it works, so I have the same problem, I need higher flow temperatures as it gets warmer. This is why I have never found weather curves or the Madoka great.

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So over 4kW of heat and impossible to turn down and keep it running. It’s very efficient though!

I think I have my answer.

Just like my 9kW, in my house at least, this Daikin heat pump also likes higher flow temperatures as the outside temperature rises. This is in terms of efficiency, mainly in terms of COP but really also electricity consumption, it’s not much different to running a flow temperature 3c or 4c lower.

It is flying along now, the best it has ever been!

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1 Like
4

What unit? Most of the Octopus installs are EDLA correct?

The installer reference guide says it can go up to 4:

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If the display menu doesn’t let you set it try going via the installer field menu? I’ve found many options on my menu settings that don’t match up with the correct installer field menu values as specified in the reference guide.

5

Hi Ben,

It is an EDLA08E2V3

I had an EDLA09E3V3 before so I am familiar with the setting.

I even have the same MMI and the overshoot is fixed at 1c, everybody notices the same thing.

6

Had anyone raised it with Daikin?

It’s documented in the manual, so either a documentation issue or a software bug, suspect the latter as it’s the same setting across multiple models…

7

I know both my own unit (6kW version) and Zak’s (8kW) both have a fixed overshoot of 1C despite the manual suggesting it should be able to be configured between 1-4, i.e. the option when logged in as the installer profile has no other value than 1 that can be selected.

I do think being able to increase the overshoot would help with the short-cycling of this unit. I had wondered if this was a firmware issue, as the reference manual does specifically say this value can be changed.

If anyone has a contact at Daikin to check if this is a bug would be great.

8

I spoke to Daikin yesterday about the issues I am having getting the heat pump to run at lower flow temperatures.

Although it was a technical helpline the person I spoke to knew nothing and said I would need a visit from an engineer.

I tried explaining that they could see everything they needed to online but I don’t think he understood.

An engineer is supposed to call me at some time, if one does I will ask.

My experience with Daikin so far is that we know more about their product than they do in terms of running them.

9

It’s be great to know what they say when you ask. I do think it’s understandable in some way that we know more than Daikin. By the nature of us having the unit installed at our homes and being on this forum we are your archetypal ‘Power User’. We’ve tried every combination of setting to try and eke out every drop of efficiency and we have access to realtime monitoring, things that I’m sure even the most experienced Daikin engineer hasn’t hadn’t the chance to do.

I have found very similar limitations in my 6kW unit as you have described above (West Oxfordshire unit on heatpumpmonitor.org). Like you, I was bothered by the system seemingly deciding some days to short-cycle and others to run as low as 29, 30C, at these flow temps some days it’ll just decide to (very) short cycle…other days (with very similar outside/inside temperature) it will settle in to a long run.

I certainly feel like the locked overshoot is what causes this unpredictability. As you say the unit ramps up immediately to a temperature over the requested flow and cuts out for exceeding the overshoot value.

For my system I’ve found a minimum flow temps of 31C means I can run the unit 24/7 and the system quickly “settles” back to heating after a DHW cycle. (Only in the last couple of days I’ve been experimenting with some Home Assistant automations to switch off heating in certain conditions, otherwise my system would have happily chugged along).

This setup leads to a minimum of 400W draw with an output of about 1.8 to 2kW of heat, for my install.

The only unit I’ve seen in this family of Daikin units getting long runs at flows around 28C and electric draw of ~300W is the 6kW unit in Whitchurch (HeatpumpMonitor.org). I’d love for the owner to let us know their settings…and if the unit is indeed an EDLA model. Even with this system, you can see that some days it will settle in to long runs and otherwise it will do the very short cycle thing.

10

Hi Sam,

I had mine running at 26/27c last Saturday, it is easily possible for me to do that once I get past the initial 20 to 30 minutes.

It has taken me a while to realise this and I will try to explain.

The heat pump is just a source of hot water, we all have the same heat pump and therefore all of our heat pumps will use the same amount of electricity to heat the same amount of water by so many degrees.

The differences are only in how low you can go on the flow temperature, 10 lpm of water at 100/97c delivers the same heat as 10lpm at 30/27c, it is only the amount of water flowing and the difference in temperature that gives the heat.

So if you think about it, my system will never produce the same amount of heat as somebody else’s settings because my radiators will just deliver more heat using their settings.

Neither will your system be the same as somebody else’s, the only thing that will be the same is that in the same conditions producing the same heat at the same flow temperature they should all be pretty much the same.

It’s hard for me to explain without writing too much but hopefully you’ll see what I mean.

The key is finding what works best in each of our homes.

I can see that this heat pump is not happy at low flow temperatures.

I don’t think it is anything other than a characteristic of the design, it is more stable and more efficient working a bit harder.

I am no heat pump designer but I suspect that this is why I find the Daikin really good when it is colder.

It just has a sweet spot where it works really well. In my house even though I can get it to run at lower flow temperatures, it is better when running slightly warmer.

11

I just had a look and the overshot setting [9-04] also cannot be configured from the field settings menu. :pensive:

12

I have the 4kW EDLA04E2V3, and can confirm that it has the option to set the overshoot up to 4. I needed to increase to this in order to prevent extremely short-cycling. Though it’s the smallest unit Octopus would fit, it still feels oversized for my relatively small end-terrace house. I’ve only had it installed since min-January, and it’s taken a while to get monitoring sorted, so I’ve not got data for “really cold” temperatures, but I’m finding that I can’t get a WC curve set low enough to just keep the house at the consistent temperature I want, since flow temperatures <25° just shut it down.

One thing I can’t understand is why most of my cycles look like this:

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I get the higher power at startup, but after running for a while the pump always decides to ramp up the compressor and the flow temperature until it reaches the overshoot limit and shuts down. No idea why.

13

Welcome to the forum @MikeEvans, interesting (and annoying for me!) that you are able to set the overshoot value, I really feel like this must be available with a firmware update as I’d expect the option to be available to this family of heat pumps (the 4, 6 and 8kW models).

With regards to flow temps, this unit is not able to go below 25°, which is why you are seeing it shutoff when you attempt that. (I learnt that from this Heat Geek video at around the 1minute mark: https://www.youtube.com/watch?v=-EUeqDSv5ag)

14

That 25° limit isn’t the end of the world, it just means that the minimum internal temperature I’d be able to arrange pure LWT WC to maintain is higher than I’m prepared to accept (I run quite warm, and am quite tight!) I did experiment with letting the heat pump manage the room temperature via the madoka, but the non-configurable -0.5° to 1.5° of target is nowhere near precise enough for me. Plus you can’t set up schedules with non integer setpoints :unamused:

I’ve ended up setting up Home Assistant to manage a setpoint according to a schedule, and turn the heatpump on/off when the madoka temperature is more than 0.2 degrees under/over target. That’s working pretty well and keeping the house within the temperature range I want. I might experiment with increasing the flow temperature and see how it affects the COP.

15

I have my overshoot on max (4) at the moment on my heat pump too - not sure why you guys cant access it.

Its become less of an issue as i continue to add underfloor heating loops (we are mid renovation) and increase load on the system.

16

Hey… I am the owner of the Whitchurch 6kW unit. Yes it is the EDLA model.

The short cycle thing is because anything over 11C it cannot really modulate lower enough. Its either that or have the house get too warm. The curve is set to be 40C at -7C and 25C at 13C I also have it set to use the Madoka modulation thing.

I also have the overshot setting. I cannot remember what I set it to but I will check tomorrow.

17

I have the EDLA04. I tried LWT mode but found the lowest power it would use is about 250W but I couldn’t get it to sit at that level - it would only sit at around 350W. The emmiters couldn’t shed the heat as the house was warm enough so the return temperature climbed, dt was narrowing so it turned off. Because it was on LWT mode, it starts up again after 3 or 4 minutes (can’t remember exactly what the time interval was - I couldn’t find a way of extending it) to see if LWT can be maintained. It couldn’t so I got short cycling.
I went to Madoka control, (which should enable the overshoot to be adjusted) and set 20 degrees during the day, 18 at night. Once the house hits temperature, the heat pump switches off for hours at a time.
I think until they manufacture 1 or maybe 2kW heat pumps, running all day long to match the heat loss of the building just isn’t going to happen (unless you leave the windows open!).
I’d say the reason you had a 44 hour run was the outside temperature looks to be between 6 and 8 degrees so your property was losing enough heat to keep the pump running. It wouldn’t keep running on your other graph as the outdoor temperature was over 10, your heat loss dropped and so you get short cycling.

18

So the ability to set overshoot is based on whether the madoka is in charge (not LWT)?
That’s not in the IRG…

19

That’s not the case on my situation.

I have room temperature (madoka) set as the control and only have an overshoot of 1 available.

20

My mistake folks, have looked back on my notes and it was when I changed emitter type to underfloor that the overshoot became enabled.

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