I’ve now switched to Leaving Water Temperature control.
Scheduled a 3C reduction at 4pm to 7pm and 12am - 4am. All other times +/-0.
Let’s hope this leaves the ECO hot water schedule at 1pm unmolested.
Madoka is now nothing more than an expensive Thermometer with a dim display 
I’ll let you know how I get on.
In my experience, the best way to run these unit is find the minimum LWT your radiators/UFH can handle, without having the HP cycle, or having it cycle every couple of hours. Se that as the minimum LWT and use the Madoka or other on/off thermostat to on/off at your desired histeresis over/under your temperature setpoint.
One key with the Madoka is that the blue led heats up the unit and makes it report the temperature higher than it actually is. To counter this, lower the brigtness to the minimum possible and set an offset in the MMI (for me, -0.5ºC works well). This effectively shrinks the histeresis from the 1ºC of the Madoka to about half (for my case), as when the HP turns off, the led turns off and the madoka sensor cools off quicker than the house.
I think Matt has already suggested this but limiting the pump speed is very useful in these units as when they start a cycle it goes full power for about 20 minutes, which quickly overheats the system.
A little update.
Two days into switching to Leaving Water Temperature control…
No shocks or unexpected behaviour!
ECO hot water takes as long as it needs at 1pm (typically around 1 to 1.5hr).
Switches back to space heating straight away.
I checked the actuator status to be sure.
Madoka shows the same room temperature as Onecta.
It also has the blue eye ring showing if the pump is on (handy).
First day I had a 3C set back between 4-7pm and 10pm-12am.
This actually turned the heat pump off completely for a while! Both smart meter, actuator status and Madoka ring showed off.
2nd day I went for 2C set back.
The outside temperatures have been quite a lot warmer than Monday / Tuesday and indeed last week.
I need more COP data yet, but the signs are very promising.
The heat pump appears to be able to run at 29 / 30C flow temperature, low wattage (backed up by low daily kW consumption and output a good amount of kW).
The input kW data is confirmed by the Smart meter data and Elec meter readings I take (just to make sure).
The output I can only trust to the MMI and the fact that we are nice and warm with hot water as we need…
Hi Matt, I just took a look at the graphs for your heat pump and I Don’t understand how you manage to get such straight lines, everything is constant. Except when your DHW kicks in. But what I found really interesting is like mine your flow rate seems to be fixed to the floor . You seem to get delta T of 6 sometimes, I never seem to get that. Usually a 5 or less, which obviously hits output.
Hi Terry,
That could be because Matt’s radiators are oversized and have no problem emitting all the heat.
It may be that your radiators don’t have enough capacity to emit all the heat at your selected flow temperatures. You could try increasing flow temp a few degrees to see if that changes things?
It’s all about finding settings that work in each individual case.
Hi David, you’re right, so that would make Matt’s radiators right sized. I run on full weather comp so don’t really choose the LWT, other than by setting the curve. When I have tweaked it up, as Matt pointed out to me sometime ago, it has a marginal effect. For some reason my delta T moves around a lot. Usually it’s around 5 or 4 sometimes 3! This of course causes the radiators to lose capacity , if I then up the flow temp it doesn’t take long for the delta T to come back down from a short while spent maybe at 6. Whereas looking at Matt’s data, his numbers all seem to rest similar almost regardless of temperature. So his output from the heat pump is really constant his temperature is constant, while mine is all over the place. I don’t have any monitoring , other than me constantly checking the MMI and my thermometers , so I have no idea if the system is cycling , or defrosting, which could therefore be causing some of this instability.
You are right too 
To know more about what’s going on in your installation you’ll need more data - more capable monitoring.
It’s not much, but you can see when the system has cycled off because the blue ring leds on the Madoka go off.
David, now that’s very useful to know. Do they go off completely and for the whole duration? Do they dim too at all for any reason? What monitoring have you got?
Hi Terry,
The Madoka blue leds are lit only when the heat pump is running.
I use the OEM level3 HP monitoring. It’s expensive and you probably won’t recoup the investment in saved electricity. But you certainly will get the best picture of what’s going on, be enabled to see exactly the effect of the settings changes you make, and sleep more soundly.
I was wondering who was the Lindfield system owner 
After spending most of the last two heating seasons dialing-in what, for other heat pumps, seems like an appropriate WDC. I’m now experimenting by copying @matt-drummer and your approach of having essentially a fixed flow temp and a large dT value (I think I’ve inferred that correctly from your dashboard).
Hi Sam, I posted my present MMI settings in Performance of 9kW Daikin - #193 by meatballs
The only thing that’s changed recently is, in an effort to pre-emptively avoid cycling now the weather is milder, I’ve put a 2 degree setback between 6pm and 6am.
This is working as hoped - the pump is normally off evenings and overnight, unless it gets cold overnight. And there’s not enough pump power to cause daytime cycling yet in this weather.
Thanks for the link, we have very similar settings. In the last couple of days I’ve gone to an essentially flat WDC and the largest dT of 10C, as I say to copy yours and Matt’s approach to configuring this smaller Daikin unit.
I’d avoided this approach when Matt posted it because I had assumed it was an idiosyncracy of his particular scenario with his very large emitters. Then I saw your system on heatpumpmonitor.org also getting excellent COP for a Daikin, and with very similar emitter spec to my own (acording to the My Heat Pump app), so thought it was worth giving it a shot to see if it improved my system efficiency too.
Looks like the forecast temperatures over the next couple of days are ideal for testing out the system in both freezing and milder conditions, which is useful timing.
Sam and David, this is really interesting. So how do you fix the LWT By creating a flat WDC? And how do you set the delta T, I thought that was a variable driven by returning water temp which we can’t fix? I am assuming, maybe wrongly that you are using weather dependent? I saw David that you are getting a cop of 5 on heating whereas I am getting a 4.1!
I have a lot , I think, of radiator capacity. I have at delta 50c , standard Stelrad figures 25.7kw.
I’m not clear still though about the issue of I have been wrestling with, the issue of the output capacity being capped. Ie at LWT 45, delta 10 and flow rate of 7L/m, max capacity is 4.88kw instead of the 7.8kw, unless there is some way to increase the flow rate?
There’s no way of increasing the flow rate of the heat pump through configuration. You can limit the flow rate as a percentage of the maximum possible (Pump limitation), to reduce the heat pump’s flow rate (this can be useful to avoid defrosts).
Setting a flat WDC you can just select a WD curve with very little adjustment. Currently mine is 36@-2 and 34@10 (though I’m still experimenting). David’s is 36@-2 and 35@12. Setting the deltaT value is possible when emitters is set to either fancoil units or underfloor, then the value range is 3-10C, in 1C increments. Matt, David and myself currently have selected 10C, which is a dT that the unit will never be able to reach, as a result it reduces flow rate to a minimum as it tries to achieve this high dT.
Essentially the aim is to have the heat pump as steady as possible because I think all of our experience is that if the LWT target temperature is moving due to the WDC curve, or the flow rate is changing as the system tries to maintain a low dT, then it never settles in to a steady state.
This is all pretty much counter-intutive to the best practice advocated for other heat pumps but seems to work well for the Althermas (based on the results Matt and David have been getting - filter to Daikin on heatpumpmonitor.org and they have significantly higher COP compared to other systems).
If you’re looking to emulate the settings, then David’s link is really useful for detailing all the pertinent controls (I’d also recommend increasing overshoot to 3 or 4C):
Yes, but you can have a slope on the WDC if that is better for your house.
We can’t specify what the physical dT is, but we can set a target. The heat pump attempts to meet this target and it tries to do this by selecting lower and lower flow rates.
Yes I am. I figure that using pure LWT mode locks out too much useful scheduling and setpoint control from the Madoka. I know that others think the Madoka is unhelpful, but I don’t share that view. I’m not finding it gives a large hysteresis. My room temps are kept within 1C.
It’s only as high as 5 on mild days. My long-term combined average is 4.0
Yes, that’s a good point and I haven’t needed to find the answer because the pump’s output at a flow rate of 33C at 7 l/m is sufficient for me this winter. But I’m thinking that if I needed more heat I would adjust the WDC curve upwards. I’m supposing that would run the pump with the same low flow rate but at a higher temperature which would increase the radiator output capability.
You can influence the low end flow rate with the delta T parameter. For example, if you set delta T to 3, the minimum flow rate increases to maintain that. I tried that once, didn’t particularly change power consumption or CoP.
Yes you can coerce the heat pump to increase the flow rate, but you can’t set a specific minimum flow rate. i.e. there’s no inverse option to Pump Limitation, something like “Pump Minimum” where you could configure the system to run the pump at 20/30/40/50% as a minimum value.
When a low dT is configured, you’re absolutely right that the Daikin will increase the flow rate to try to maintain that value. But it doesn’t maintain a constant flow rate, instead it oscillates between the minimum and maximum flow rate (and the highest flow can be a factor in inducing defrosting).
I’ve no idea why they haven’t just configured the system to step up to a higher, steady flow rate and see if that new value can maintain the dT, then repeat the step increase if dT still can’t be maintained.
I feel like with all this in-the-field data and knowledge we now have, if Daikin had some of us from this forum discuss with their firmware developers we could get these systems much better optimised. Obviously that will never happen 
Agreed!
@mortstar Sam, thanks for that, again yours combined with David’s reply is really helpful. I’ve also grabbed David’s settings from the other chat. I’m assuming we have to use installer code to change these? With regard to your point about LWT, flow rate etc. There is a logic I see to what is happening, but I may be misunderstanding, which is why I have been trying to get answers out of Daikin for a few weeks but with no success, so far!
So the logic I see is that priority 1, is get to LWT, priority 2 is to get to Delta T and priority 3 is to get the flow rate down to minimum, or resting rate. I have noted across the various schedule that we all have slightly different resting rates. Mine is 7.1, I think it was David’s around 6.6, not huge differences and maybe insignificant. Now the rub to that as I see it is that once that flow rate is there, on weather comp anyway, there is nothing to budge it. Delta T is driven by the return water temp so isn’t a true variable, flow rate has become fixed, in any event once delta T is below 10 ( assuming that is the target set) , flow rate can’t increase because to do so would be to drop the flow rate even lower, further away from target. I’m not sure at that point what the system does. Does the system stop at any point? I haven’t noticed that my system is cycling which is good, but my Delta T has got as low as 3, which means I’m only getting a trickle of power. But what happens if it gets lower? Anyway I’m going to respond to David now and continue this helpful dialogue.
@dmajwool David thanks for your excellent reply.
I was a little confused by your reply on the whether you are using weather dependent, I’m also not sure if weather dependent and pure LWT are interchangeable, I thought they were one and the same. But from your reply you seem to be using the madoka to supplement the WDC and I don’t understand how you are doing that, and why it doesn’t conflict with the ‘pure weather dependent mode/ pure LWT “.
On the issue of the restriction of power that’s one issue, but the linked issue is that, should one assume that if you have , as you and I both have, a heatloss of around 7.5 kw, and if you are getting by with a max of 4.88kw and a min of say 2kw, then doesn’t that tell us the heatloss was massively overstated?
Because if I have understood heatloss, the theory is if we start of with the house at equal to the outside temp at -2, at that point there is no heatloss, but if we want a temp of 21c , then we need 7.5k to get there. At the other end, when the house reaches 21c, and outside the temp is still -2c, we still need 7.5kw, because we have a heatloss actual now of 7.5kw. Except we don’t. So if you are keeping a constant temperature of 20/21 degrees and you are using about 3kw, then isn’t that your real heatloss, how can it be otherwise? So the 7.5kw heat loss is 2.5x overstated. And I am seeing something similar. Does that make any sense?