Posted by: @ms13sp

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I have moved into a property with a 8.5 Ecodan. It has UFH downstairs as zone 2 with a heatmiser thermostat for each room. This causes issues and I just leave them all turned up to 24. 

But I think it is time to replace them all with one thermostat. 

 

So, should I get a second Mitshibishi thermostat and then enable auto adapt or something else entirely? 

Goal is to save money but also stop the inconsistency that does sometimes arise from issues with heatmiser seeming to timeout or not work unless 3 or more thermostats are asking for heat (issues on sunny days)

Thanks in advance

Welcome to the forum and you are thinking in the right way, ie about reducing the complexity and number of controls.

The first questionto answer is why do think you need an active thermostat at all, what is wrong with running on pure weather compensation without auto adapt, or indeed however you are currently running it?  Is it because one (or more) room(s) get too hot from time to time due to solar gain (for example) or something else?

Once you have answered that (ie whats the problem you are trying to solve) it will be possible to answer the question!  Personally I wouldnt advise spending anything until you have answered this question (maybe for yourself not just the forum).

This isnt being flippant BTW, its a serious question, as only you know how your house responds and in particular in what circumstances it doesn't respond as you would wish.

I would echo what @jamespa has said, @ms13sp. I too have an 8.5kW Ecodan servicing a mix of ufh and radiators only mine is all configured as one zone and it works fine on pure weather compensation. If you prefer your bedrooms slightly cooler, it’s perfectly possible to “balance” those radiators in such a way as to achieve that, but understanding in a bit more detail what you’re trying to achieve is always the best starting point.

Thanks for the replies and questions. 

Yes, I am trying to prevent several rooms getting too warm. 

Along with saving money, I am also trying to see what could help feel like I am not adjusting the weather curve all the time. 

Even when it feels I have it just right for several days, some day comes that is rainy and sunny and I have to turn it down. Or a day comes that is sunny and windy and I then have to turn it up. Maybe that is the way, but I just don't want to touch it 🙂

Hope that helps clarify my goals. 

Posted by: @ms13sp

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Even when it feels I have it just right for several days, some day comes that is rainy and sunny and I have to turn it down. Or a day comes that is sunny and windy and I then have to turn it up. Maybe that is the way, but I just don't want to touch it

 

If you get the weather curve right and rads balanced and run 24*7 with trvs open and thermostats set to max you should rarely have have to touch it.  How are you currently running and what are your wc parameters.

I have never gotten the weather curve to work correctly on the controller itself. It seems to always want to cycle. Maybe rounding errors or something else. 

I use an ESPhome with the weather curve programmed into it. Works well and keeps things low and slow. I find on days like today where the wind is bad that the flow needs to be adjusted along with sunny days. Mostly when air temp is above 3. 

Current weather curve is 40 at -7 and 30 at 3. Target temp in the house is 20. 

Now that I have looked it up - https://github.com/gekkekoe/esphome-ecodan-remote-thermostat allows you to do auto adapt mode. Has anyone tried this? 

Posted by: @ms13sp

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I have never gotten the weather curve to work correctly on the controller itself. It seems to always want to cycle. Maybe rounding errors or something else. 

 

I use an ESPhome with the weather curve programmed into it. Works well and keeps things low and slow. I find on days like today where the wind is bad that the flow needs to be adjusted along with sunny days. Mostly when air temp is above 3. 

 

Current weather curve is 40 at -7 and 30 at 3. Target temp in the house is 20. 

OK so back to your original question/the question I posed (now slightly modified in the light of new info)

The first question to answer is why do think you need an active thermostat at all, what is wrong with however you are currently running it?  Is it because one (or more) room(s) get too hot from time to time due to solar gain (for example) or something else?

Once you have answered that (ie whats the problem you are trying to solve) it will be possible to answer the question!  Personally I wouldnt advise spending anything until you have answered this question (maybe for yourself not just the forum).

This isnt being flippant BTW, its a serious question, as only you know how your house responds and in particular in what circumstances it doesn't respond as you would wish?

@jamespa Looking back it is only on warmer days or really windy days that I have had to adjust anything after moving to the ESPHome curve. So, yes. The curve is working.

I guess I am asking the question because it has taken so much time and energy to figure things out thus far that I wonder if I will be having to fiddle with this anymore. 

Also trying to see if others with Ecodan's have tried the auto adapt and if it saved them any money or even just the worry of having to adjust things to handle "off" days. 

Thanks

Ecodan 14kW on auto adapt and various MelCloud schedules. I never have to fiddle with it, when you get hit with a warm day (cor... remember them, feels like a life time ago) it seems to adjust fine and let the house find the correct balance.  All rads K2 and K3 on one zone. It has been in this mode since 2019 so I think it has learned the houses heating and cooling pattern by now!

Posted by: @ms13sp

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@jamespa Looking back it is only on warmer days or really windy days that I have had to adjust anything after moving to the ESPHome curve. So, yes. The curve is working.

I guess I am asking the question because it has taken so much time and energy to figure things out thus far that I wonder if I will be having to fiddle with this anymore. 

Also trying to see if others with Ecodan's have tried the auto adapt and if it saved them any money or even just the worry of having to adjust things to handle "off" days. 

 

Thanks

I cant comment on autoadapt (a) because I dont have an Ecodan and (b) because its likely to be house dependent.  I tried the Vaillant equivalent and it was inferior to using pure weather compensation which happens to work very well for my house except at the season extremes when solar gain means I need to apply a limiter. 

If your Ecodan  controller is not already in a representative room then it may be that if you fitted a Mitsubishi external temperature sensor (nb not thermostat) then autoadapt using this as the temperature reference would help, but as I say above for reasons I cant tell.  What you dont want is third party thermostats (you have essentially disabled the ones you have ao they can remain because they are doing nothing!)

@ms13sp, adjusting weather compensation settings to properly match a home is always going to be a long term process so if there's tinkering still needed then that's not unexpected. The key thing, as @jamespa has said, is that you've now removed the thermostats from the equation so there's no fight for control.

You said you're using the CN105 adapter, and in particular the custom WC curve on it. The ability to customise that curve is a significant improvement on Mitsi's own WC curve and I've been using it as well for a little while now, so there are a couple of observations I'd make on it.

Firstly, you said you had your current weather curve set to 40 LWT at -7 OAT and 30 LWT at +3 OAT. If that custom curve is working well in general, obviously leave it be, but are those two points the only points on the curve? If so, that would suggest the LWT will remain at 30 for all outside temperatures above 3 degrees, and that would definitely make the house too warm on hotter days, and that's where the ability to add extra temperature points would definitely help. My curve, for instance, has flow temperature settings for outside temperatures of -10, 0, 5, 15, and 18. That means that if I find the house getting a bit warm in the spring, I'll be able to adjust the flow temp down at OAT 15 without affecting the curve below OAT 5 - I can tweak a part of the curve in isolation. I could, of course, dictate the flow temperature at every degree gradation between -10 and +20 if I wanted to, because the curve allows a (theoretically) infinite number of points on that curve. Even if you do have more than just two points on your own curve, I'd still urge you to adjust in this more granular way so that, as the weather is warming up, you can "lock in" the known good behaviour of lower OATs and just tweak the warmer part of the curve as the conditions arise.

Secondly, you said the wind is a significant factor. The CN105 adapter's custom curve comes with three modifiers you can make use of - a manual offset, a solar gain offset and a wind chill offset. Although each of these is doing nothing more than offsetting your curve by plus or minus up to 5 degrees, it allows you to isolate different factors and work with them more closely. I reserve the manual offset for exactly the same job as the standard Mitsi offset i.e. the ability for me to manually choose to increase or decrease the flow temperature for any given OAT on my curve. However, I use Home Assistant to programmatically offset the curve downwards to compensate for solar gain if the sun is in the right position to be making my back room a sauna and, of course, to remove that offset later in the day once the sun is no longer a factor. Similarly, I can deal with the wind in a similar way, using various sources of weather data to pick out bits of data that are relevant to my house and, if necessary, offset the curve upwards to account for wind chill. Dealing with these factors separately means there are times when I'm offsetting the curve downwards by a degree for solar gain and upwards by perhaps two and a half degrees for wind - the CN105 adapter applying both these offsets meaning the weather compensation curve is adjusted by a net amount and the world keeps spinning as I'd like.

These suggestions definitely shouldn't be considered until you're somewhere close on your more general compensation curve journey since the adapter won't fix a badly setup system but given the level of configurability you already have at your disposal and the fact the remaining concerns you have are well within the remit of the adapter's functionality I'd suggest these points are worth considering. I'm more than happy to go into more detail if you decide you'd like.