Posted by: @hotheat

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WC will save energy by using a lower flow temp when it warms up but isn’t going to do anything at current freezing temps.

Drop in power and flow temp is defrosting

If it was cycling the flow temp would be increasing and decreasing every 10 mins you will get cycling when it’s warmer and the heat pump can’t reduce its power any further to maintain the flow temp so it has to turn off for a few mins then back on to heat it back up hence cycling on and off.

Under the reports tab in the app are energy reports these can show estimated consumption and generation.

The lower end looks good at 32C that is the lowest temp I can use without the unit cycling you may be able to lower it further it’s just trial and error.

I can't answer all of your questions but here goes for some of them:

(1) I am not sure which delta you are referring to - rad to room or LWT/RWT. The latter in the mage you posted looks OK, about 5 degrees.

(2) there is a lot of debate about this, see other threads. The general principle is that WC is the best way to run heat pumps, with Auto-Adaption if you have it (Ecodans do, I believe) which tweaks the WCC Set LWT, taking into account indoor temperature. But not everyone runs them this way.

(3) The fall in the LWT in the image you posted is a defrost cycle. The giveaway clue is the LWT goes below the RWT. Over-shoot (modulating) cycling looks similar, but the LWT stays above the RWT. Examples of both can be seen in my recent posts in this thread.

(4) Visual inspection of the LWT/RWT trace, for the characteristic rise and fall in LWT, and distinguish between defrost and modulating cycles as above.

(5) Can't answer this one, as I have a Midea unit rather than an Ecodan.

(6) The principles are the same at both ends of the WCC, in practice you are more likely to tweak the left hand end in cold weather, and the right hand end in warmer weather. The end points just describe a (mostly/usually) linear relationship between the outside air temp and the Set LWT.  

Ref 5 - you need the electric and heat meters to get the full data , usually about a £700 add on

Posted by: @walkers-heatpump

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Ref 5 - you need the electric and heat meters to get the full data , usually about a £700 add on

For sure, that is the gold standard, but you can get some Ecodan data, see posts by @kev-m, though obviously it comes, like my data from a Midea unit, with the caveat that it comes from manufacturer supplied raw data, and as a result dieselgate/compressorgate precautions apply. 

@cathoderay the data I've seen without the metering set up hasn't looked great, especially during summer season where it overestimates standby power 3-4x greater

@hotheat

have you been able to get the consumed/delivered data from the main controller? It's accessed using the far right of the four buttons.  The every hour drop in consumption in this weather is a defrost. The ASHP stops for a few minutes to do this then starts up again.  Overall you're using more energy though because the refrigerant and the flow temperatures drop and need to recover.    

Posted by: @walkers-heatpump

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the data I've seen without the metering set up hasn't looked great, especially during summer season where it overestimates standby power 3-4x greater

There certainly are discrepancies, but I am fortunate that for the energy in I can measure them, as I have an external heat pump dedicated kWh meter. Having done comparisons over time, I have found on average (there are minor apparently random variations) the true (meter) reading is about 1.18 times more than the values derived from the Midea data (reported amps and volts in, collected at minute intervals over modbus, and then used to calculate the kWh in values). I have now incorporated this correction factor into my current reported data, but not they historical data (before 29 Nov).

The energy out data I am less sure about, because as you correctly say I would need a lot of expensive and invasive equipment to verify it. The flow rate (I use modbus minute by minute flow rate x LWT/RWT delta t x specific heat of circulating fluid, which in my case does have glycol, to calculate it) I am fairly sure about, my Midea runs with a pretty steady flow rate, and the value agrees so far as i can make out with that obtained from an analogue flow meter in the circuit. The specific heat value I use is 4.05, for a 10% glycol mix, again that shouldn't be too far out. The values that are uncertain are the LWT/RWT - where and how exactly are they measured? - but as it is the delta not absolute values I am interested in for the calculations, I might not be that far out for the delta t, even if the absolute values are both out (the same way) by a few degrees. But the bottom line remains, I can't prove the modbus collected Midea data is correct.   

I'm mostly interested in the heating side of things, that is when energy use goes up greatly. Even if the errors are greater in the summer, it doesn't matter, insofar as I am not looking at that data, though of course it might well affect things if I looked at very long time frames eg annual (S)COP.   

To optimise, you really need real time energy consumption from the ASHP. My pump runs off an exclusive breaker in the consumer unit, and I use a shelly EM with a clamp round the live exiting the breaker ( https://shellystore.co.uk/product/shelly-em-50a/) for about £50. I collect the data using Home Assistant on a Raspberry pi with the very easy-to-use shelly and melcloud integrations, I keep a log/graph of flow, return and outside temps, Power usage and H/W tank temp. Takes a little while to set up but once it's there you can home in on getting it super-efficient. The image shows quite low power and a lower flow than return temp as it's just starting a defrost, but you get the idea of where it's been from the graph.

@gary thank you! Yes I checked on the control panel and it’s 37/33 at the moment so 4 like you said. Sounds like I am on the right track then more or less

@cathoderay thank you - appreciate you taking the time to respond to all of these qs and useful to understand defrost vs cycling. Yes I think I will end up with WC with a night time setback once cold snap ends