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 happens was a bit chilly, so I turned the heating on for the first time (we generally like the house to be around 20.5 so when it dipped to 19 we found it a bit cold). We are actually a radiator down at the moment because I'm redoing our kitchen, which includes the removal and relocation of the radiator. Anyway, I've set up all of the relevant parameters in a graph, as per this screenshot:

Thus, so far seemingly so good and generally the outlet/inlet graphs seem to be pretty much typical of a midea, slowly rising to the set outlet flow temp before cycling.

Going back to the automations in homely, I have temp sensors in all of the upstairs bedrooms, and one in the hallway. This one in fact, which is a tapo:

Having these sensors then allows me to link and monitor these all either via the tapo app, or again via home assistant:

I have set up an automation so that when the temperature rises above 21.5, this reduces the values for the WC curve within the heat pump controller, the intention being that this will hopefully slowly reduce heating output to reduce overshooting. Whether this works as intended remains to be seen, as I'd accidentally disabled this automation without realising when I had the heating on today, and then wondered why it didn't work...

Anyway, this is where I have got to so far. Hopefully as said this is of some interest and will update as said in terms of how we get on. COP for today was around 4.8, from the midea control panel so seems ok. Incidentally homely would generally estimate the COP at around 0.5 above whatever the midea control panel would specify. I have kept the homely for now, in its box and if it transpires that this way of operating it needs too much fiddling or doesn't work as well, I can re-install it. I'd rather not though as it has been rather liberating ditching it, and it's algorithms, simplifying it and taking back full control. Please also feel free to critique any of the above as I would not class myself as an expert by any stretch, with plenty still to learn about how to optimise ones ASHP.