I do not know Ecodans... but don't mind betting you SHOULD meddle! 

Join a user group or ask questions in this group. I see there are YouTube videos too.

Write down changes so you can reverse if necessary.

The curve almost certainly should be adjusted and likely lowered so you can operate with all TRVs and thermostats fully open and set above 19 deg. 

Can you see current flow temp (leaving)? And outside temp?

By way of example my LWT is currently 37deg. Outside temp 4deg. Inside temp 21deg

Posted by: @carpenterstation

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I have no leverage, no system design, no hand over details. .

Situation normal then 

Posted by: @carpenterstation

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and I have been told not to meddle….

as @tim441 says you are almost certainly going to have to meddle if you want your system to work efficiently.  

Posted by: @carpenterstation

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the UFH valves are sticky. Some need replacing - but if stuck they remain open and the pump stops firing when everything is up to temp. But there are 9 valves all independently controlled by room thermostats which could be causing me some inefficiency.  But all are set to 19degrees all the time - and the stat for the radiator part of the system (upstairs) is set to 17.5. TRVs on all rads to balance the upstairs rooms. Most upstairs rooms are not in use. 

That mode of operation is going to cost you a lot!  You have to forget everything you learned about controlling high temperature boiler based systems, low temperature systems particularly those based on heat pumps must be controlled differently to work efficiently. 

Basically you need almost everything open and TRVs/Thermostats set well above the desired temperature.  Then to adjust the WC curve down to the lowest point possible consistent with heating the house.  The 'Automatic' function of the Ecodan cant possibly work if you have UFH valves and TRVs independently shutting off sections, so it will not be doing its job and the WC curve will be likely be more or less where the installer left it/the factory default, which wont be good.  Not heating out of use rooms will almost certainly cost you more money than heating them, because it means that adjacent rooms must supply more heat hence run at a higher flow temperature.

In summary:

• ensure that there are no external devices turning the heat pump on/off (smart/dumb thermostats, Hives , Honeywell evohomes etc)
• ensure that any TRVs are set well above the desired temperature and any temperature operated valves are always open
• balance the radiators/UFH (if you have any adjustment possible)
• ensure the WC curve is as low as possible when system operated ~24x7 (you can certainly miss out the peak cosy period)

The other thing to consider is how the system deals with rads and UFH.  They really dont combine well and many systems end up forcing the Heat Pump to work at the higher flow temp required by the rads thus sacrificing the principal benefits of the UFH.  Does you system 'mix down' the water to supply the UFH or is it supplied with water at the same temperature as the rads.

What max flow temperature are you running at (from the WC curve or actual flow temperature wehn its very cold)?  This piece of info is crucial.

Just to add to the data collection....

East coast of Ireland. 185 m2 house - 100mm external insulation, 325mm loft insulation, 100mm underfloor insulation, ufh downstairs, rads upstairs. 

Viessmann 151-A 10kWh ASHP.

January 2025 Usage 512 kWh (heat 443, DHW 69.1) excluding 30 hours power outage - thanks Storm Eowyn!

January 2024 Usage 591 kWh (heat 476, DHW 115)

According to degreedays.net Jan 25 only marginally colder in these parts.

2nd year of usage of ASHP - improvements gained through son being at Uni for part of the time - no 15 minute showers(!) - slightly reduced water temperature, and minor adjustments to heating curve.

@carpenterstation just to add some Ecodan specifics to James' great commentary.

We know you are running in Weather Compensation mode from the image you posted of the controller on the other thread

Post an picture of your compensation curve, to get to it press the main menu button then go to heating, on right side of the screen you will see a magnifying glass press the button under that option and that shows the compensation curve you are running.

Will look something like this

@jamespa I don’t know what temperature I am running at ? Where will I find that out? 
if I turn up all the trvs and turn off (up) all the thermostats to force the whole system to be completely on all the time won’t the house just get very hot? Sorry for the stupid question but how will the temperature be controlled with no controller operating?

There is some sort of a mixer on the UFH manifold but I don’t think there is any mixing (other than the low loss header) on the heating system itself

I have no idea whether this is good p, bad or indifferent!

Is this the temperatures? It is cold today!

Posted by: @carpenterstation

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Is this the temperatures? It is cold today!

Yes thanks, good plot

Posted by: @carpenterstation

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if I turn up all the trvs and turn off (up) all the thermostats to force the whole system to be completely on all the time won’t the house just get very hot? Sorry for the stupid question but how will the temperature be controlled with no controller operating?

Yes initially, but then you turn down the weather compensation curve until the house is at just the right temperature, thats the whole point.  The weather compensation system then adjusts the output of the heat pump according to the outdoor temperature so as just to balance the loss from your house (which is determined by outdoor temperature principally).  It is a bit counterintuitive initially, but it works, actually rather well.  As importantly doing it this way means that your heat pump is operating at the lowest possible flow temperature which is the greatest efficiency.

I suggest you spend a couple of days reading about weather compensation on this site and possibly also heat geek before tinkering, so you understand it.  Its not new, in fact its been compulsory for boilers in some european countries for a couple of decades because it makes boilers more efficient too.  In the UK we ignored it and it has cost most of us an extra 10% on our heating bills.  With heat pumps the effect is greater so we can no longer ignore it.

My house (and that of many others on this forum) is running on pure weather compensation with almost all radiators open loop, no TRV, no thermostats.  It works brilliantly.

Ok thanks I think I am getting there (slowly) last question- how do I adjust the WC to balance the house when everything is open? And should I remove all the timed constraints on water and house heating (from the Mitsubishi controller)

upd… all thermostats off, all trvs fully open. Feels like I am taking an enormous gamble to efficiently overheat the house - but I’m trusting you guys !

upd2… and WC dropped to 32degree flow at -3 and 25 degree flow at +15. Let’s see how we go!

Posted by: @carpenterstation

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Ok thanks I think I am getting there (slowly) last question- how do I adjust the WC to balance the house when everything is open? And should I remove all the timed constraints on water and house heating (from the Mitsubishi controller)

You adjust the end points of the sloped line.you presented earlier.  This will be somewhere in the menu, probably the installer menu.  I would reduce the flow temperature at the low end (oat -10 I think) a degree or max two degrees at a time, perhaps no more frequently than once every 12 hours.  Once it gets close less frequently.  You should probably set times controls to avoid the expensive cosy period only.

It may take several days to get right.  Please do read a bit about it before leaping in though, particularly in the manual.  Don't expect instant results.

Also turn off auto adapt whilst you go through this process.  Probably you won't turn it back on.

PS. If you do initially massively overheat your house that's great news.  It means that you will make larger savings when you get the WC curve down.  

🙂 the manual!! Ha ha.  84 languages and print so small it is illegible. Poor quality images and impossible to follow. 

I think I can use batteries to avoid the peak cost … but yes I will watch that

@carpenterstation when I moved from fixed temps to weather compensation my annual usage dropped from about 8050kwh to 5800kwh. Huge saving .. especially when topped off with time of use tariff.

You're already using WC but I'd take a small bet your savings will be 10 to 15%... or more. By lower temp curve, more efficient usage...and maxing the tariff

@carpenterstation your aren’t running auto adapt the curve symbol I circled means pure weather compensation.

Here is a video on how to adjust your curve, it’s the same process I showed you to access the curve just hold down the menu button to access the adjustment menu