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Testing new controls/monitoring for Midea Clone ASHP

benson · 2025-09-14T21:44:38Z

Hi all, I thought it might be of interest to others if I document a bit about the above, which is mainly the removal of Homely from our system and the installation of something that essentially uses the manufacturers controls via home assistant, particularly as the native control panel for Midea, and their app, are not great. Over this heating season the plan is to compare how we get on both in terms of comfort levels, and costs, so hopefully this will be a good test. Background: Firstly, a bit about the system, which we've had for just over a year. 160sq m house, with very average insulation so we're never going to be running particularly low flow temps. 16 radiators in total, with estimated heat losses just under 8kW and a 12kW Clivet (midea) installed. Overall, we did not have the smoothest of experiences with our installers. There were a lot of issues with general quality of workmanship, being left a cold room or two, and not being able to achieve the reported design max flow temp of 45 at minus 2. At minus 2 generally we'd need outlet temps of around 47/48 to keep our house warm, after a bit of trial and error. The installers recommended homely and we went for this, which works ok but our general feeling was that it left us with too little control and I personally didn't like that end users have to go through the back door to access their installer dashboard. It also exhibited some slightly strange behaviours with overshooting. Here's an example of some of the isssues we had with Homely: You can see in the graph above that Homely set the flow temp at 50/51 when there was no need to do so. Quite mild outside and the heating essentially was off for a few hours. This would happen once or twice a week and just generally didn't seem to quite align with the low and slow principles. New controls: I researched a lot of potential options, and even contacted Clivet themselves who interestingly just recommended getting an on/off thermostat and connecting this to the ASHP. Not being a fan of the above (mainly due to advice on here), I looked at other options. Planet Atmo seemed like a good option for pure weather comp and was compatible with Midea. This would link to the ASHP via the modbus in the same way Homely does, and allowed a lot of controllable parameters and monitoring, via their app. However, they wouldn't supply direct to the public so that ruled them out. I have tried the Midea Smarthome app but it is quite basic, and it just keeps disconnecting with the control panel. I had been able to relink it but now I just can't get it to work at all so I've given up on that. I then came across a Midea ASHP controller called Svenar. I couldn't fully work out what this device offered, truth be told, but it sounded like it might work so at around £65 I thought we'd give it a punt. It connected via modbus and then allowed control/monitoring via home assistant. Home assistant- We in fact already had this. I purchased the HA green a while back and in fairness hadn't really been using it that much, with only one automation set up for a smart plug on our tumble dryer to notify us when it had finished! For those who aren't familiar, the best way to describe it is an open source system/repository that allows connection and integration of a load of smart devices in your home. You can then set up automations so if something happens to one smart device (or entity within that device so for a temp and humidity sensor the particular entity could be selected as the temperature reading) it can then influence another separate device to run a command. The HA green is a straight out of the box solution which was very easy to set up. Svenar- when it arrived, again very simple to set up and this was immediately discoverable in home assistant, which was a good start. What I didn't realise, which was a massive bonus, was just how many parameters of my ASHP I'd be able to see, and control, within home assistant via Svenar. There are around 200 odd, and hopefully this screenshot gives an idea which is a very small snapshot: Now I cannot profess to know what all of these parameters mean, but a bit of googling, and delving into the instruction manual, allowed me to pick off the key ones that I wanted both viewable, and controllable, in a separate dashboard rather than having to trawl through the list of hundreds. Again, for those that don't know much about HA it allows one to create custom dashboards with cards, or buttons that will display certain entities and allow toggling on/off, changing values etc. It's also worth pointing out that HA works really well on a smartphone so the above dashboard I created is very easy to read there. Even the wife commented that it was easy to use and turn on the heating- a decent endorsement indeed... As you can see on the above, I've added the parameters for the WC curve so I can easily tweak this as required once we see how we get on when the weather turns. Putting it to the test: Today as it hap...

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Air Source Heat Pumps (ASHPs)

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benson

(@benson)

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Joined: 2 years ago

Posts: 301

Topic starter 19/03/2026 12:24 pm

Ok some more info on the new setup which may be of interest- specifically the comfort offset automation which adjusts the flow temperature if the IAT is outside of the comfort parameters, and an interesting observation over the last couple of days now that it is a bit warmer.

The above shows the comfort offset history for the month, so it will adjust the LWT by 2 degrees C either way, depending if the IAT is undershooting or overshooting. It hasn't actually run that much, which is what I was hoping/expecting. On 13th March it must have been windy and needed a boost. On the other days where it has offset -2, this will be down to solar gain.

What the adjustment effectively does when warmer, is that it turns the ashp off- so if the set LWT is then below 29 degrees C which is the lowest temp that it will run. This actually works perfectly. As per this graph (red arrow where the comfort offset has pushed the set LWT below 29)

I think now I can confidently say this is our ideal setup in terms of control strategy, and I can probably leave as it is.

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cathodeRay

(@cathoderay)

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Joined: 4 years ago

Posts: 2898

19/03/2026 7:26 pm

@benson — well done! My auto-adapt does pretty much the same thing, infrequent but useful adjustments. The advantage of using our own code is that we can tweak it to achieve control that works for our particular setup.

Midea 14kW (for now...) ASHP heating both building and DHW

👍

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benson

(@benson)

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Joined: 2 years ago

Posts: 301

Topic starter 20/03/2026 11:27 am

Posted by: @cathoderay

↑

My auto-adapt does pretty much the same thing, infrequent but useful adjustments.

I presumed when Gemini was writing the automation code for me, that it was data farming from your forum posts about your set up 😆

It does work well- thanks for all of your help, and everyone else who has advised along the way.

😂

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cathodeRay

(@cathoderay)

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Joined: 4 years ago

Posts: 2898

20/03/2026 8:08 pm

Posted by: @benson

↑

I presumed when Gemini was writing the automation code for me, that it was data farming from your forum posts about your set up

Spooky! I think you already know I don't use AI much, but if I did, and found myself asking it a question and finding the answer seemed curiously familiar, I might end up thinking I need to start taking the tablets again!

Posted by: @benson

↑

It does work well- thanks for all of your help

A pleasure, and thank you for documenting what you have done here. I am sure the other who have contributed have also been glad to do so.

Midea 14kW (for now...) ASHP heating both building and DHW

👍

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Tasos

(@tasos)

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Joined: 1 year ago

Posts: 87

20/03/2026 8:32 pm

@cathoderay For what is worth, it was recently pointed out to me, in a Greek heat pump forum, that certain high-end manufacturers, like Hitachi or Daikin, do indeed offer an IAT compensation mode.

So I had a look at a Hitachi Yutaki ASHP manual and indeed there is an option of room temperature compensation, which I quote:

"Room Temperature Compensation

If room compensation is enabled, the calculated OTC supply set-point is adjusted based on the difference between room temperature and room set-point in order to reduce the room error. The amount of room influence can be adjusted by the room temperature compensation factor setting (can be adjusted, default 2).

Example

Compensation factor = 2,

SR1 (room set-point) = 20,

TR1 (room temperature) = 23

=> S1 (supply set-point) reduced by 2 * (23 – 20) = 6C "

Even though this is a rather crude approach, I think it does show the future, which is very well predicted by your reported actions here.

Midea MHCV10WD2N7 R290, 5.8kWp energy community solar power.

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cathodeRay

(@cathoderay)

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Joined: 4 years ago

Posts: 2898

20/03/2026 8:42 pm

@tasos — despite what Gemini may have been up to, I don't claim any originality for what I did, which was simply to implement a basic feedback loop! I had the idea of such a DIY implementation after hearing about Ecodan's auto adapt mode, and thinking setting up something similar in python should be very straight forward (and it turns out it is). I haven't done the same thing for forecast weather, because a forecast is only a forecast, but I am sure it could be done without too much extra effort ('if forecast windchill > X then increase LWT by 1°' etc) by anyone who wanted to add it.

Midea 14kW (for now...) ASHP heating both building and DHW

👍

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