The first picture shows its operating according to water law but Im confused about the screenshot which seems to show water law for Zone 1 and then for Zone 2.  Are you sure you havent programmed one end of the curve in Zone 1 and the other end in Zone 2!  It might be worth checking FSV 1032 as well although I dont think this should be a problem.

Is it operating constantly at 34C or was that a spot measurement, it could be cycling on and off peaking at 34.

I dont have a samsung; someone who does may be able to be more precise

Thanks

Looking further on this site in thinking I'm suffering from this

https://renewableheatinghub.co.uk/forums/renewable-heating-air-source-heap-pumps-ashps/samsung-weather-compensation-oddities

"had a bit more success today and got the flow down to 32degrees and got closer to balance, but ultimately the temp kept increasing and would not stop even as I reduced the temp on the controller."

happens because the system is oversized and/or its mild outside.  Cycling occurs because the heat pump cant turn down sufficiently to match the demand from the house.  This manifests itself as the flow temperature rising above the set point until it reaches a threshold at which the heat pump decides to switch off for a while.  Thus the heat pump switches on and off so that the average output (over time) matches the demand.  All heat pumps (and boilers) do this.  A 'right sized' heat pump will likely do it at an OAT of 10-12 or thereabouts.  An oversized heat pump may do it down to the point at which cycling due to defrost kicks in!  Cycling does cause an efficiency penalty, but it is currently unquantified (and possibly exaggerated for historical reasons).

Thats why I asked "Is it operating constantly at 34C or was that a spot measurement, it could be cycling on and off peaking at 34."

Looking at it since it's been a steady 34

The heat pump is definitely oversized. We could have done with 9k but they came in 8 or 12.

So if I've parsed that other thread correctly. 

I need to set my lowest warm weather flow to the lowest my system can manage, namely 34. Then use my thermostats to turn it off during these mild periods.

Or I can change the 2093 so it cycles and keep my flow temperature lower?

Yes, that sounds correct.

I would say try both options and see which works best for you. I wouldn't aim too low though, if you already know 34C is required to dissipate the heat produced - maybe try 30C to start and see how often it's cycling (you really don't want it short cycling multiple times per hour).

I prefer to let my room thermostat control the on/off cycles, but that's just my personal preference. In milder weather the system may be on for an hour then off for 1-2 hours depending on OAT.

So I turned my thermostats down last night 

And when I woke up this morning, although the bedroom was 22, the flow temp in the boiler was only 12.5, so it had clearly been off for a while, and I could see the thermostat controls were unlit, showing they weren't asking for heat. 

I just went back a moment ago though and despite the thermostats not asking for heat, the flow temp is back up to 42. The pumps aren't on and the radiators are cold though so the house isn't heating up. Does this sound right? 

I'll give the manual a good read this evening and try and figure out those 2091, 2092 and 2093 settings

Posted by: @terry

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I need to set my lowest warm weather flow to the lowest my system can manage, namely 34. Then use my thermostats to turn it off during these mild periods.

 

Or I can change the 2093 so it cycles and keep my flow temperature lower?

Definitely its in the 20xx FSVs.

Conversely it may be that you need to reduce 2022/2032 further as well as changing 2093 so it operates on pure WC.  I don't know if Samsung calculates the energy integral (the difference between target flow temperature and actual flow temperature integrated over time).  If it does then it could/may/will use this to adjust the cycles so that on average they deliver the same amount of energy as would have been delivered at the target flow temperature, which it can do by inserting an I component into the control loop.  I know Vaillant heat pumps use the integral for some purposes, I have yet to find out if mine uses it for this purpose.

I have the same pump and if I am operating it correctly you need to touch/hold/release the blue bar on the bottom left of the controller which says "heat". It should then change to give you three options, one of which is Auto. Select Auto and you are then on Water Law. Hope this works for you.