Hi Sarah,
I’ll ignore the second bit can’t even begin to understand what that might means 
As for FSV 4052
So this is setting the difference between LWT and RWT (Is this called deltaT?)
Generally what I have seen on my system is that this is always 3deg or very close to 3deg
So am I correct in saying my FSV 4052 is set to ‘3’?
I assumed the deltaT was a just a product of the system design, I didn’t realise the heat pump could control this value!?
Thanks
You’re right, deltaT cannot be directly controlled, it results from LWT and flow rate. For a given constant LWT, a lower flow rate will result in a lower RWT and thus a higher deltaT.
Hi Andre,
So the heat pump slowing the flow rate is its attempt to increase the deltaT to keep the LWT below the water law threshold for the given outside temp in an attempt to run continuously and when the slowest flow rate can’t achieve this the heat pump has to stop.
Yes?
Thanks
Hi Sarah, I wonder if this might be something that has been introduced with Gen 7 as what you describe doesn’t happen with my Gen 6 12 kW Samsung. The graphic shows LWT rising to the target LWT of 35C after a setback and remaining stable until the internal thermostat switched the heat pump off. FSV 2093 = 1. Water Law was set to 35C at 10C OAT and 35C at -5C OAT in order to eliminate the effect of any changes in OAT during the run. The gradual fall in heat output balances the expected fall in emitter output as the difference between radiator temperature and room temperature falls.
So this graphic shows that LWT is indeed controlled by the water law settings when FSV 2093 = 1. If the thermostat had been set much higher, room temperature would have continued to increase. Eventually the emitter output would have fallen below the minimum ASHP heat output and LWT would have started to rise above target LWT, whereas with FSV = 2-4 it would then cycle off.
By contrast, when my Samsung is in Quiet mode, it behaves very differently to the above and completely ignores the water law settings as demonstrated in the graphic below. I am not sure whether changing FSV 2093 to 2-4 would alter this behaviour, so room for a bit more experimentation!
Yes Ian, it sounds like it is. But why not look? (I assume that your installer revealed the mysteries of accessing the factory/installer settings on the remote display.)
All the PWM is doing is adjusting the circulation flow so as to maintain your preset (LWT - RWT). Within limits, the heat pump controller doesn’t really care what this flow is - it can be a low flow with high deltaT or a high flow with low deltaT - as long as it can shift the required duty into the circulating fluid safely.
Conventional wisdom is that provided the (LWT - RWT) is somewhere around 3-5degC then all should be well. Higher flows will give hotter emitters for a given LWT (the corrollary being that you can reduce the LWT a little for the same emitter temperature - so improving your CoP) but higher flows cost more pump energy, so there is an economic balance to be struck.
As usual, nothing is simple… 
.
Sarah
Hi MIke,
I can’t argue with your observations or conclusions. But that’s not what the User Manual implies, so I think I’ll consult Samsung to clarify.
Sarah
Hi Sarah,
I will look to see what mine is set at tonight.
Yes my installer showed me the two fingers 
Finding the balance seems to be the trick which ever way you go about it, I bet I could play with all these settings over the whole winter and still not be 100% sure I was running as efficient as possible.
Thanks
Hi Tim & Glyn,
I’ve just submitted my system.
Thanks
Ian
Approved! 
It looks like you’ve got air trapped in the DHW loop, which results in a data error flag.
See Removing Air from Heating Systems — OpenEnergyMonitor 0.0.1 documentation
I would so love to have them document every algorithm they featured in their MIM controllers!
Agreed Oto!
I’ve spent several months trying to reverse engineer the algorithms, with modest success. (I’m planning to publish my findings on this forum if I sense that there’s a demand, but there aren’t that many Samsungs around…)
Hello Ian Martin,
In response to your recycling issue:-
My system is a Samsung Gen 6 16 kW unit, which has operated over 2 winters. The ASHP flow is direct to a ring main, where all the u/f manifolds are supplied and the return is via a 100L buffer tank. I refer to it as a buffer tank, but in reality it is now just a volumizer as using it as a buffer tank for both flow and return was not hugely successful. The Samsung unit is not controlled by any weather compensation or any other external method, it just modulates itself using the return flow temperature. My observations over two winters are no excessive recycling and a reasonable COP, measured using the available data from the Samsung control system. The Samsung unit is also excellent at modulating its own output, I have observed it running at 4kW electrical when it is really cold and seen it modulating down to 0.1kW(e) and also shutting down to 0kW. I accept I have a particular advantage as my property is two floors of concrete which provides a large thermal mass and this assists to provide a relatively stable heat demand. The control system to manage the properties heat demand in the 19 separate zones is by19 thermostats which once set up are not changed. To control the electricity demand of the ASHP, i.e. to enable it to shut down during periods of high electricity prices, I just use individual Optimum controllers to control each of the u/f manifolds (5). So as an example to shut down the ASHP during the high price period between 4pm and 7pm, the APP programmer shuts the 2 port valves for all the u/f valves and this in turn causes the ASHP flow to return to the buffer tank via a nrv. This flow of 40 degrees very rapidly increases the temperature in buffer tank and hence the return to the ASHP. The Samsung unit then modulates itself down to close to zero electricity use, in turn at 7pm when calling for heat from all the circuits it slowly ramps up to meet the prevailing heat demand or 4kW (max).
So my conclusion over a couple of winters is to leave the ASHP on and let it control itself, which it seems to do very well. I appreciate that weather compensation is maybe a better option in a radiator situation where you haven’t got the advantage of a large thermal mass/store, but I’m sure the Gen 7 will probably have a better control system than my Gen 6 unit. Also please note I haven’t got the complexity of meeting HW demand as I have left this circuit on the old gas boiler, I also have fitted antifreeze valves and I only run my ASHP from October to April. RJK
I don’t think this is correct, in my experience and according to my interpretation of the manual when #2093 =1 the LWT is still governed by WL. I think #2093 just controls what’s conditions stop and start the compressor and control different circ pump modes, I don’t think any #2093 settings affects LWT.
I’ve just tested again setting #2093 =1 and setting the room temp to 27C, the LWT never increased higher than my WL setting
This is a shame, since some users have reported that it would be very useful to have a way to temporally shift the WL curve for a quick boost of heat when running in room temperature mode.
Correct.
Thanks! There’s a few Samsung’s on the site now, use this link to filter by Samsung: https://heatpumpmonitor.org/?period=all&minDays=0&filter=samsung
Yes you are quite correct @glyn.hudson (and @MikeJH), I’ve just had this confirmed by Samsung:
“When FSV 2093 is set to 1 (room temperature only on/off) The heat pump is controlled using the water law parameters, however when target flow temperature is met the heat pump keeps running but will ramp down to minimum Hz. This control is maintained until controller set point is reached.”
I misinterpreted the manual (and my controller display) and will add a correction to my previous posts. Sorry all!
Sarah
That is good news to ear! At least we’re not hallucinating with our readings…
It’s actually a good thing for anti cycling measure. Although it would definitelly lead to higher consumption (but not lower CoPs).
Hi Tim,
Thank you.
Yes i know its on my list to try and sort out but its quite a big list!
As this install was replacing an aging combi using microbore they had to replumb the whole house, it made a bit of a mess 
EDIT:
Todays DHW cycle is running and it got hotter nearly 48deg before the data error occurred yesterdays was closer to 40deg. Looks like the AAV are doing their job hopefully it will keep getting better till the problem goes away altogether. I was going to bleed all the radiators again this weekend as well.
I checked FSV 4052 and it was set to 5 deg
I changed it to 3 as that is what my system seems to get although I have seen it as low as 2deg!
EDIT - I do see a 5deg DeltaT on a DHW cycle.
Which makes me think same as @Andre_K that the system design has more impact on the DeltaT than this setting. Although I bet some systems could have their DeltaT adjusted by the heatpump if they are capable of emitting more heat then just a radiator circuit like mine.
This interests me.
I was wondering what is the lowest/slowest my system can run?
If I set FSV 2093 to 1 and as my thermostat is set to manual on/off and I leave it on once the system reaches the LWT temp for my water law settings the system should then run as low as possible while the LWT keep rising. Yes?
Obviously I’d keep a close eye on it to make sure it didn’t get too hot once I was satisfied I could set FSV 2093 back.
Thanks for that input, it sounds like you have quite a complex system.
I would really like to get my Water Law settings nailed down so I can essentially just leave it on and running during the months we need heating whether that is achievable I don’t know at the moment.
I’m not massively concerned with running costs as we are on Octopus Cosy and with a 9kW battery so far we are only using cheap rate electric and we still have capacity to use more without having to pull from the gird at more expensive times.
Yes Ian, I believe you are correct. As Samsung have clarified, with #2093=1 the compressor will run at minimum speed once Water Law temp is satisfied, so if you don’t let the roomstat switch it off (because you have it on manual control), LWT will keep rising until emitter heat output equals house heat loss. You could do some sums to predict what the LWT will get to, or you could just try it and watch…
Keep us informed!
