@rfcalan Welcome to the crazy world of heat pump optimisation. I've 2 x 12kW Gen6 Samsungs with same controller as you, and similar size DHW so I'll attempt to explain what I do.

There's two of us here so no doubt a similar DHW demand. I reckon we use around 3kWh each day on DHW which is completely dwarfed by the eye-watering consumption on heating, typically 50-60kWh each day currently but has been much more in the December seriously cold spell. So, my first action would be to optimise the heating - tweak the weather compensation settings down to get the lowest water temperature that still gives you a comfortable house and avoids regular on-off cycling of the heat pump, which is inefficient. 'Low and slow' is the key here and you will need to experiment a bit to see how your house responds at different external temperatures.

But, to pick up on your DHW points:

1. Forced mode is a good idea if you need a load of hot water and don't have a tank full. However, I don't use Eco, I keep mine on Standard and this keeps it topped up (within a margin) all day. My target temp is 50°C and this works fine. The only time I might need to used Forced is if we have visitors and more showers in a morning. 
2. As far as I know, eco merely sets a target 5°C below your set point. So, yes, it saves a bit (note earlier point about the departmental paper clips budget) but, as you say, can lead to the odd cool bath if you're drawing a lot off the tank when it's not quite reached it's low temp run signal. 
3. Not sure what Quiet does exactly, other than the obvious. I understand it reduces power output and all the advice I have seen says don't use it. 
4. I've just started to experiment with using two on schedules for DHW, one at 1300hrs (corresponding to warmest part of day and, in summer, best PV yield) and one late in evening (2300) when heating is set back a couple of degrees.  DHW is prioritised over heating so this scheduling is designed to avoid big central heating demand times. My DHW tank loses around 0.3-0.4°C per hour so I'm hoping the tank is only dropping 2-3° before I need to use the hot water, typically only early morning showers and evening baths anyway. 

Good luck!

Simon

@dunlorn Hi Simon

Thanks for the information.

I have managed to pin the Heating Engineer down for a 30 min call to go through this in detail.  Been chasing him for a while.

Eco has a drop of 10 degrees, standard 5 degrees.  His opinion was to run a schedule on Eco morning and afternoon / evening and off during the night.  His opinion was that with Standard the number of recharges is more than Eco therefore it impacts the priority on the underfloor heating.  He also stated that the cost difference in usage between both is small, it is the impact on heating.

The underfloor heating weather compensation is set to something like 35/37 degrees and 45.  I have just reduced the difference by increasing by 2 degrees to increase the heat.  I understand that slow and steady is the way, but I have found that rooms are not reaching their desired temp.  

I will see how these settings go and update.  I will take some readings of usage and check back.

Two other thing from me. 

1

I used to have an OSMA system, Gen 1 about 16 years old.  It used serial connections (low voltage wired) to connect the Thermos to the controllers all driven from an oil fired boiler. They replaced the controllers and thermos with Heatmiser (latest generation) as I decided it had to be done at some point.

I opted for a wireless thermos as I through it would be a good idea to move them around the zone if needed...wrong!  They are supposed to be wall mounted as the sensor is underneath and they need the air to flow around them.  I have a ThermePro heat and humidity sensor I have used  as a bench mark for room temp.  I found that with my old OSMA, the two were about 0.3 - 0.4 degrees difference, which I think is about right having two different systems to measure.

With the Heatmiser Thermos, I have some that are 0.3, and some that are 1.4 degrees difference with the ThermePro.  I lined up all the Heatmiser Thermos in the same room and none of them read the same.  I called Heatmiser to complain and they told me that their SLA for Thermos is 1 degree either side, which means a 2 degree swing. This is a big impact when you are running slow and steady as the room temp could be off by +1 degree to start with.

2

I had the power off today and my controllers did not come back on when the power went back on.  I spent ages trying to work it out.  Found out that you have to turn off each Thermo, then switch them back on and increase the temp to fire up that zone.

I then had to turn the power off again literally as soon as I had done this.  When it went back on, the controllers came back with no intervention from me.

Turns out that the thermos do not constantly chat to the controller, every 20 mins or so unless they do something like reach their temp.  Next time I have been told to leave it alone and after 20 mins it will turn back on again.  The way I got it working was a force start which also works.  

It might save people the hassle of getting the system up again if they go through the same issue.

Alan

@rfcalan Sorry, I can't help you with your thermostat challenge!

Mine uses a Hive thermostat but it's not great, just promoting on/off cycling with 0.1°C hysteresis. What I've started to do is set the Hive a couple of degrees higher than I want the room, and adjust the ashp water temperature until I get a flat line on my (Hive app) temp profile. So matching heat input to losses and keeping the place around the desired 18-18.5°C. The heat pump then becomes the controller, modulating and occasionally stopping the compressor as the buffer tank reaches set point with the Hive then just an over temperature cut-off. It means the system is 'on' more but at low power and with good efficiency, and the house stays consistently warm. 

settings for the DHW. 

Here is my flow temp and hot water tank temperature.  I have the same Samsung HP and Controller as you.  The diagram below may be useful, I will respond in more detail in the next post.

[edit] added the solar thermal annotation to picture

Posted by: @rfcalan

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The problem I find with Eco is that the drop of 10 degrees can be an issue.

I am not sure where you get 10 degrees from, in eco mode, the target temp is about 3 degrees less than standard

Posted by: @rfcalan

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Would it be better to run a force start for a bath and leave it on Eco for all other water demand?

My settings are such that if heating is on, heating will not run more than three minutes if there is a need to "charge" the hot water tank, I very rarely use anything other than economic.

Posted by: @rfcalan

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Does anyone run a schedule where Eco comes on for 1hr twice during the night to stop it running too cold? 

I switch off hot water at 10pm, then on again at 6:30am - no need to run over night.  then off again at 9am on again at 4pm.

Posted by: @rfcalan

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What is the biggest difference between Eco and Standard?

Economic will be "x" degrees less than standard, I have set this to 3 degrees less.

Economic will not use the booster heater (element)

Standard will use the booster heater after y time and get close to the target temperature (on the rare occasion I tried standard it did not get all the way to 55 though.

Posted by: @rfcalan

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would it be better to have this schedule set to standard?

I think this depends on how good your heat exchanger is in your cylinder.  My heat exchanger can absorb over 12kW from the heat pump so can fully charge my 300L tank in 22min, I don't need to use Standard.  [I need to check the maths as stratification makes calculations difficult]

Posted by: @rfcalan

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I would be interested to hear what others have done

I only use economic, we only shower [never bath], I have heat recovery on the shower waste water which recovers 60% of the heat from the water going down the shower drain, and I have re-used my solar, back boiler thermal store.  So my situation may not be that common.

I think if you are going to bath you probably need a lot of hot water.

What water cylinder do you have?

I am happy to share my configuration settings, if needed.

@william1066 Hi Bill.  Thanks for the reply.

Regards to Eco and the 10 degree drop.  I assumed this was standard unless the heating engineers have set this up this way.  I will find out.

I have made changes to my water schedule.  05:30 then off at 11:00 and nothing after that.  We then shower and do all the washing etc during these times.  If I need something in the evening I can then either force or add a schedule.

I have reduced the DHW to 50 degrees.

Regards to the UF heating.  I had set this to 3 degrees + over their set thresholds and I found that it pushed the heat better to the rooms quicker.  I have reduced this to 2.5 degrees and there is little difference in the performance.  I notice that the water flow to the UF heating dropped by about 2.5 degrees when the DHW was heating up.  So the theory is to reduce the number of DHW recharges to lower the impact on the water flow to the UF heating.

The average room temp is about 20 - 21 degrees.  I work from home a fair bit and my wife does too and I found that 18 - 18.5 degrees was not quite warm enough to sit in.

One last question.  I have set up the Heatmiser Neo App and paired all of the Thermos.  Any ideas if you can control the DHW at all remotely? How did you get your image you displayed?

Thanks

Alan

@dunlorn Thanks for the reply.  I have set my rooms to around 20 - 21 as I found 18 ish to be too cold to sit in.  I have set the differential to 0.5 on the Thermo and I may change this to the default 1.0 degree setting.  I will try different settings and record the energy usage over a 24 hr period and compare.

I found the Samsung App and can control the DHW from it (temp changes).

Posted by: @rfcalan

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Any ideas if you can control the DHW at all remotely?

I do so via Home Assistant and the modbus interface to the Samsung Heat Pump - but takes some effort to setup.  In any case the Samsung wired remote is in my kitchen so I can walk up and switch the hot water on there if needed.

Posted by: @rfcalan

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How did you get your image you displayed?

From Home Assistant UI.  There are other options involving less effort which I can share, possibly on the weekend when I have more time.

Posted by: @rfcalan

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I found the Samsung App and can control the DHW from it (temp changes).

I would be interested in more details here, if you have time to share.  Thanks

@william1066 how did you get the data? Are you connected esp to the pcb or something, would you mind sharing your setup?