Hmm, but that is strange no ?
You should have primary valve position set to space heating circuit. So I have it to 0. Then anytime there is DHW heat request, or AF/AS cycle request it must switch your 3-way valve position 1.
While 0x409D is FSV3071 seems it’s not working reliably ?
I’m reading position of 3-way vale from this address #0x4067 so probably you are using a wrong address ?
From NASA spec
0x4067 ENUM_IN_3WAY_VALVE NASA_DHW_VALVE Hydro_3Way 0 Room, 1 Tank
| So maybe give it a try… |
|---|
Ok, so after 2 cycles, I can conclude that 0x408B is the DHW operating state (generating DHW is ongoing), while as expected 0x4067 is the valve position. So yes based on 0x4067 you can determine whether it’s stealing DHW heat!
Yup, now the question is if AF/AS cycle starts and I will detect it (no compressor, 3-way valve switching position to DHW circuit) if disabling DHW will immediately switch back to space heating circuit while anti freeze protection is running ?
I hope so. If not, then it’s useless. Also there will be a slight delay to turning off DHW because it takes some time until modbus register 3-way or compressor change. But I hope it’s quick enough to save as much heat from DHW tank as possible.
But if this is not working I guess the only thing would be to have DHW constantly disabled and make own automatization for DHW heating and enable it only during DHW heating request.
Once temperature will drop below 5C I will start monitor AF cycles during night when space heating is turned off to confirm the behavior.
SAMSUNG! Why do we need to do this? Is really that hard to have a setting where user can choose this behavior ? I will never buy a Samsung heat pump again and any other brand which lies about specs. I wanted a small pump and here I am with 14kW unit crimpled to 8kW in software… Well done, Samsung. So now I have to live with this until it breaks and it could be decades… Or maybe not - rant off 
This is a rather good question, but I hope the DHW disablement will do the trick. Normally it should be detected and applied in less than 10 seconds. So it should be quite the optimisation over the 5 minutes length DHW water heat recirculation.
Keep us posted!
I agree. I will monitor these reaction times and let you know if it works as intended. From my charts that AF cycle lasts 8 minutes! Just enough to steal few degrees from water tank per cycle. Now imagine there are 3 or 4 cycles overnight…. Here you can see 3 but only because there was DHW reheat at 2:00. Otherwise I would expect 4-5 AF cycles. And it was only around 0C outside. And you can see all the reheat done at night was wasted on these AF cycles and at 9:00 the DHW must have been reheat again.
Hopefully you can detect the start of an AF/AS cycle quickly enough to close the 3-way valve before any significant heat loss occurs.
Still to determine, by observation:
I though AS is related to heat pump on it’s own that simply it will start the pump for 5 minutes just to circulate a little bit of water so e.g. pump is not stuck in case the water pump is not active for 24h. This is usually issue with rotary pumps that when they are not use for couple of days it tends to stuck. I have such pump on mine coffee machine and last time when I was on vacation for 6 days it got stuck. So I don’t know why AS should be related only to DHW. Look at this chart from September when I was not at home so there was no DHW or space heating request. You can see it starts every 24h for 5 minutes. Of course during this action switching 3 way valve to DHW position. But why it is switching to DHW ?? I don’t have any explanation for this. AF I would understand but AS ?
To be honest I don’t know if deactivation of DHW would stop AS cycles if pump is not operated for more than 24h. Makes no sense to me.
I know this because I had it like that and my “issues started“ only when I’ve connected DHW tack. Until then all was fine.And another thing which driving me nuts with this pump is this 70W pump consumption in case it’s idle for few hours…. pump simply start to consume 70W for something, With Sarah we investigated it is heating some internal compressor stuff or something but why it has to do this in summer lol when there is 20-30C outside. Look at the bottom of the chart at that constant consumption of 70W. Sometimes it drops to 11W when it’s really idle but most of the time is taking 70W and doing nothing. So if the pump is not running the whole day it takes about 2kWh of electricity.
And look here how it crimple COP. From 3.28 to 3.05 average COP fro the last day… Only because of this stupid 70W consumption.
Did we discuss disabling the Base Heater, @Michal_S? Re-reading the Installers Guide I note (p122) that you can manually disable the heater using the K-buttons. Might be worth a try…
Indeed, that would make sense but that is not how the logic works on my Gen 6 unit. The pump runs AS for 5 mins exactly 24h after the last DHW cycle ended. It does not matter if the heating (and pumps) were running an hour ago, an AS cycle will run if it’s exactly 24h after the last DHW cycle ended.
The system seems to have no knowledge when the pumps last ran - the AS feature seems to only look at when the DHW cycle last ran and ended (at least on my Gen 6). Hence my question, as it’s directly linked to the DHW cycle, will the AS cycle still operate if DHW is disabled.
It seems to be on a countdown timer of 24h that starts whenever a DHW cycle finishes, and nothing can reset that timer other than another DWH cycle ending.
I wish we could see the code / logic the controller uses.
On my Gen 6 unit I do not have DHW enabled, just CH. The AS cycle behaves exactly as expected, if the pump has not run for 24hrs, then it runs for 5 mins-ish.
Hmm, yes but isn’t it too risky ? Especially in winter ? Do we know what it does exactly ? It’s a heater which heats compressor or some heater which heats that water reservoir so it will not freeze ? I don’t know to be honest. I saw some gen. 7 pumps which does not do it but I will have a look once more.
This is really strange. If it is like that it’s really stupid because I can’t se no reason why it should pump the water every 24h through DHW circuit. Next summer I will deactivate DHW for two days so let’s see what happens
Look at this. Exactly 24h after DHW cycle finishes.
But there was no space heating between. But if you look here you can see there is no AS cycle running after last DHW cycle. According your opinion it should start AS at ~21:45 the next day but there is nothing and space heating started on 22:30. So in my opinion it is always 24h after the last pump run no matter it is DHW or space heating. I would not seek some sophisticated logic with these Samsung heatpumps
And yes, now @toadhall confirmed it as well.
Look at this Gen7 pump, this is completely different story. Look at that smooth modulation. There are no phantom electricity consumption when pump is not running. Also COP from different world when we compare mine.
This first gen HT quiet with R32 is really bad. And I had to buy it. What a luck…
Thank you for the confirmation.
Seems the 24h countdown timer is set from the end of the last DHW cycle if present, and if not then from the end of the last heating cycle. Where both heating and DHW are present, the timer is set from the end of the DHW cycle only.
Nope, check my post. If there are space heating cycles after last DHW cycle then AS is not started.
I agree that makes a lot more sense (and looks to be the case on your Gen 7), but as I outlined above, that is not how my Gen 6 operates 
I was just thinking that you could disable it for the warmer 6 months of the year (so not too much effort to reset, if just twice a year).
All it does is warm the OU base plate - look at the sketch on p192 of the Installers Guide, item #2.
Dear Michal,
Can you check the flow rate of the circuit during the 70W consumption period, as it sounds like a pump is running, not really a heater (more in the 250ish W).
Cheers
You can see on his charts above that there is no flow during these times.
You’re right! but could there be additional pumps that are taken into account in the global consumption?
Definitely not the water pump since flow is 0 at that time. I have just one pump. With Sarah we have observed some internal compressor temperatures were raising slowly so it must be some small heating element. Maybe it heats oil or something I don’t know. What I know that after a good DHW heating where everything is hot it is not doing this for few hours and then it starts…
