Posted by: @stevet

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So are you suggesting I reduce the -2 to -4 (I have adjusted the 50C down to 48) Currently my settings are -2C -  48C and 15C and 30C

Yes, I would- based on what you have said with respect to your house being too warm, and furthermore you want your linear relationship between OAT and flow temp to extend beyond -2. Try 48 or 49 at -4 and see how you get on perhaps?

Regarding the data analysis-  the benefits of having the modbus connectivity, and indeed having this so easily accessible via the indoor control panel, becomes a real bonus and you'll soon forget about the useless native app. There are several options as cathoderay says. I use home assistant and use a couple of out of the box solutions which were quite simple to set up.

@benson 

I have now got -48C at -4C and 30C at 15C  - I am amazed at what appears to be very little heat at the RAD giving us 22C . Last night I nearly had to open bed room windows as felt like hot humid night in the summer! We very poor app is showing about 1Kw every other hour.  I have read about Home Assistant, aware this can be wired to the Midea Wall Unit.  My main focus currently is getting the system running as efficiently as possible while giving us a comfortable living temperature. Initially I was more focussed on using the low overnight tarriff, but understand a lot more now. Solar has generated 15KW today which is pretty good. My sons gaming PC draws almost as much electricity as the heat pump! I now remember to turn DHW and Heat after each modification. 

To expand on what @benson has said about the lower end of the WCC, thee key point is the curve flat lines either side of the end points:

T1SETH1 and T1SETH2 are the LWT (flow) temps we set, T4H1 and T4H2 the OAT. Either side of the slope, which sits between the end points we set, the 'curve' flat lines. If the OAT goes below T4H1, the LWT doesn't get any hotter. By moving T4H1 a bit lower, the LWT continues to rise to that lower point, and only then flat lines. I have at times set my T4H1 to -4, but it is currently -2°C.   

Posted by: @stevet

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I am amazed at what appears to be very little heat at the RAD giving us 22C

Find another bit of metal in the room and put the back of your hand on that, you will then appreciate the rad is warmer that you first thought! Plus it is mild at the moment, and a 30°C @ 15°C setting means that 15°C OAT, the rads will be, and are meant to to be, at less than blood temperature. They will get to blood temperature at about 10°C OAT with your WCC. They only need to reach these temps when it is mild outside, as the heat loss is much less. 

Posted by: @cathoderay

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Posted by: @stevet

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I am amazed at what appears to be very little heat at the RAD giving us 22C

Find another bit of metal in the room and put the back of your hand on that, you will then appreciate the rad is warmer that you first thought! Plus it is mild at the moment, and a 30°C @ 15°C setting means that 15°C OAT, the rads will be, and are meant to to be, at less than blood temperature. They will get to blood temperature at about 10°C OAT with your WCC. They only need to reach these temps when it is mild outside, as the heat loss is much less. 

You are right.  I think I would turn the system off a the moment and the house will hardly lose any heat. I will almost certainly getter a better perspective when we return to more normal winter weather.  I also probably have oversized rads now due to the over conservative heat loss calculations per room and design flow temperature. Personally I am not too concerned as it least gives me headroom and beong to hot is not a bad problem.  

We had some friends over for dinner and they experienced the nightmare scenario about 7 years ago with a complete novice builder using no design criteria installing a useless system only because the planning permission for a massive extension insisted in a heat pump. No heat loss, first heat pump installed by the builder. Result freezing house they have now sold. They have been put of heat pumps for life which is  a shame. 

Posted by: @stevet

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They have been put of heat pumps for life which is  a shame. 

It is indeed. The same tales of woe can be heard in pubs up and down the land. None of my immediate neighbours has a heat pump (and one has just replaced their oil tank, which tells us something about their long term plans) and even my more rational friends start rolling their eyes and raising their eyebrows when I say get a heat pump right, and it just works. 

Quick question I read another old post from @curlyKatie who was also setting up WC curve. on a Midea.  She had this screen

 - I have similar but the Weather temp set is blank - I assume this is correct ? 

I have checked my W_O PLATE W-OUTLET TEMP if LWT (flow) and TW_I W-INLET TEMP is RWT (return) - both are 32C which sounds about right as it is now 8C outside. Also put a temperature gage on a rad - 30C which is again I think about right. 

Slight fly in the ointment our Room Temperature is now 23C (our hallway  - location of the Midea wall unit ) was open to our kitchen/Diner  - had cooker and oven on for an hour and three people so this probably raised the ambient temperature a degree).  

Posted by: @stevet

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I have similar but the Weather temp set is blank - I assume this is correct ? 

It's not actually 'blank' and you have 'ZONE 1 H-MODE HIGH TEMP' (Midea-speak for your main circuit) set to ON as it should be. When it was first set to ON, it should have taken you to the curve selection window, and the one you want is curve 9, which is the custom curve where we set the endpoints.

Posted by: @stevet

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I have checked my W_O PLATE W-OUTLET TEMP if LWT (flow) and TW_I W-INLET TEMP is RWT (return) - both are 32C which sounds about right as it is now 8C outside. Also put a temperature gage on a rad - 30C which is again I think about right. 

Because Midea units cycle most of the time, these values change all the time, which is why charts are so useful. That said, for some units including mine there is a sweet spot at around 7°C OAT when they stop cycling and really do run 'low and slow'.

Sorry that was a screenshot of  @curlyKatie  - mine has all the Weather Mode Settings to OFF - there are four settings 

Posted by: @stevet

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mine has all the Weather Mode Settings to OFF

You need to set the one shown in the photo you posted to ON, you will then get to choose which weather compensation curve (1-9), choose 9, that is the custom curve, the one on which we set the end points, and you are done. You may or may not need to turn the heating back on after doing that, sometimes changing settings turns the heating off. Check the main home screen to see whether it is on or off. 

Posted by: @cathoderay

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Posted by: @stevet

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mine has all the Weather Mode Settings to OFF

You need to set the one shown in the photo you posted to ON, you will then get to choose which weather compensation curve (1-9), choose 9, that is the custom curve, the one on which we set the end points, and you are done. You may or may not need to turn the heating back on after doing that, sometimes changing settings turns the heating off. Check the main home screen to see whether it is on or off. 

Thanks, sorry for daft questions. I now have this set to ON as per screenshot and selected curve (9).  What as the Midea been doing for the last 3/4 days, RADs and power consumption and house are cooler (now 20-21C).  Was it doing anything with my 28/14 and 50/-4 settings?  I followed the instructions from "Grahams Heat Pump Channel" on youtube, he talks through the curve settings, but does not mention the first bit. 

One final question..... is there a Midea Wall Unit parameter that shares data with the NON Samrt-Home App - For some reason I am not no longer seeing any consumption data - -what data there us available is now blank - used to be able to see current, hour...day and so on. I have carried out the usual reboot of the wall unit as the App only normally manages about 6 days max before it loses all connectivity with the wall unit. It is talking as can see the Wall Unit and see Heat and DHW are both on etc. 

thanks again for all your help 🙂 

Posted by: @stevet

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One final question..... is there a Midea Wall Unit parameter that shares data with the NON Samrt-Home App - For some reason I am not no longer seeing any consumption data - -what data there us available is now blank - used to be able to see current, hour...day and so on. I have carried out the usual reboot of the wall unit as the App only normally manages about 6 days max before it loses all connectivity with the wall unit. It is talking as can see the Wall Unit and see Heat and DHW are both on etc. 

There's no setting. The app just doesn't work properly. We had exactly the same on ours- it would completely disconnect and/or this data would vanish.