Greetings, I have that Daikin Heat Pump also but I don't have the Dixell. If you have a second pump I assume there is a buffer? Can you perhaps upload a picture of the plant room so the pipework can be seen and others may be able to advise.  I do run mine on LWT continuously but , as I understand, on my system the Madoka is just a temperature gauge so it is different to yours.

Thank you @jancold, you could write down what I know about heat pumps on a box of matches. Id rather ask here than ask my installer, you guys are more friendly and more knowledgeable.

Its a full new system and radiators, we're running it around 19⁰c day and night as we don't like it too hot, heat loss survey was 3.6kw.

@craigh, welcome to the forums... and you’re right, it is a friendly bunch here, so you’re in the right place. 

Just to be clear up front, I don’t run a Daikin myself and I don’t have hands-on experience with the Dixell controller specifically, so take this as general guidance rather than brand-specific instruction. That said, the principles you’re dealing with here are common across a lot of heat pump systems.

From what you’ve described, your understanding is broadly on the right lines. The secondary controller is there to decide when it’s worth circulating heat into the heating system based on the leaving water temperature. Its job isn’t to optimise efficiency month by month, but to stop the system pumping water around that’s simply too cool to be useful.

In most properly set up weather-compensated systems, this value shouldn’t need regular adjustment. Once it’s set sensibly low enough, it should largely fade into the background and allow the heat pump’s own weather curve to do the heavy lifting. Constantly chasing it up and down with the seasons usually creates more problems than it solves.

At the sort of low flow temperatures you’re already running (high 20s to low 30s) it’s normal to set the minimum low enough that circulation isn’t being artificially blocked. Your thinking around avoiding unnecessary engagement of the 3kW backup heater also makes sense, especially this early on while you’re still learning how the system behaves.

If the house is ending up too warm, that’s almost certainly a weather curve issue rather than a controller issue. Small, slow adjustments to the curve and offset are exactly what you should be doing. Heat pumps respond best to patience... tweak, wait a day or two, then reassess. Resist the temptation to micro-manage it hour by hour.

Overall, for someone two weeks in, you’re asking the right questions and approaching it the right way. Like I said, keep changes small, let the system settle and don’t worry if it takes a bit of time to land on the sweet spot.

Posted by: @craigh

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Is ESPAltherma worth getting and is it easy enough to set up?

@julianc, @lucia, @radwhisperer & @toodles what's your take on ESPAltherma?

@editor I’m afraid I am totally ignorant of whatever ESPAltherma is and had to look it up! Most of my monitoring is carried out with Daikin’s VERY BASIC app via the MMI and that which I obtain through the Homely kit. As far as I know, I am an Arduino-free home! Regards, Toodles.

@editor thank you, yes I'll admit to being a bit too quick making changes (I'll blame my ADHD), it doesn't have to be espaltherma, I haven't a clue what the difference is with all the monitoring equipment, does @toodles not like that specific one? Im open to suggestions if he favours another one? Without one of these do you have to go and see if the heat pump keeps stopping and starting to see if it is cycling as i read that's not good either? I'll take your advice onboard and slow down with the changes. Thanks again

Posted by: @craigh

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Is ESPAltherma worth getting and is it easy enough to set up? Many thanks everyone.

Just to clarify for @craigh, I don't have a Daikin and I don't use ESPAltherma. I just know what it does.

Now to clarify for everyone else who may not be familiar with ESPanything...

These days, the Internet of Things (IoT) is the whole topic of Internet-enabling all kinds of devices - fridges, doorbells, vacuum cleaners, televisions, heat pumps and many more. One of the most influential bits of this puzzle is an ESP microcontroller (older ones called ESP8266 and newer ones being ESP32). In essence, it's a very small microchip on a very small circuit board that can have a few wires attached to it to link it to something that needs controlling and then programmed to do what you need it to do. They cost a couple of pounds and wifi/bluetooth is already a part of what it does so a lot of manufacturers use them. In fact, all the discussions on another thread about Solis or Growatt solar inverters mention a wifi dongle and that's basically an ESP32 chip with slick plastic outside to make it look nice. Ditto Mitsubishi's wifi adapter. Ditto the network bit of my robot vacuum. The list is almost endless.

ESPAltherma is the work of someone calling themselves Raomin. He or she has written some code that you can freely download and apply onto an ESP32 module you buy for yourself and then connect to a Daikin Altherma heat pump. The code allows the ESP32 module to query the Daikin's serial port and then transmit that information to somewhere of your choosing - Home Assistant would be a very typical example. That means you could have plenty of comprehensive stats to monitor to your heart's content.

The big limitation as far as I can see it is that ESPAltherma doesn't allow you to control the heat pump except for (optionally) turning it on or off. For that, you'd probably want to look at an alternative solution that uses modbus to connect with the Daikin Home Hub.

The bigger question, though, is back to you, @craigh, and what problem you're wanting to fix with ESPAltherma. Are you just wanting to get more comprehensive stats out of your heat pump or are you keen on being able to control it better? And the Brucey Bonus question is what your appetite is for a bit of techie rolling-up of sleeves? Opening the door on Home Assistant or any other form of home automation system is not necessarily as scary or complex as it may first appear but it does presume you've a bit of a tinkerer's mentality - not necessarily for technophobes.

Other than that, I'll add my vote to the running list agreeing that it is a friendly place here and it's good to welcome you in.

@craigh I am using Daikin Onecta for quick checks on consumption and use a Homely smart controller attached to the MMI for ‘management’ purposes. Regards, Toodles.

Cheers @majordennisbloodnok, an excellent and informative answer without getting too technical so I could understand it easy enough. My head was a bit blown off when I had the heat pump installed, got a snippet of info on how to use the room thermostat to operate it and kept having to get up in the night to turn it down. Yes I am the type to tinkle, I really just want to know that the heat pumps running efficiently and that my changes to the WD curve aren't running it in a way that will cause excessive wear on components and it sounded like one of these gadgets was the way to go. I do struggle with technology but I'm always willing to try. Many thanks.

@craigh, when we had our system installed seven years ago, there was virtually zero information available. We had to grapple with everything in the dark and it took me two years to discover that something called "weather compensation" existed and that ours was switched off.

That's the real value of forums like this. Your learning curve will be steep, but it will be extremely productive because you're willing to learn. By next winter, you'll be well on your way to mastering your system.