Hi all, so this night the outside temperature was below 5C so I could test DHW deactivation and sadly I have to say IT DOES NOT WORK.
From the chart you can see there were 5 anti-freeze cycles during night when space heating was turned off. The first AF cycle was executed at 1:01:15. At 1:02:00 the automation detected it’s an AF cycle and disabled DHW completely but sadly, 3-way valve didn’t return to a space heating circuit and stayed on DHW heating circuit for the complete AF cycle which lasts 6 minutes and finished at 1:07:15. For 5 AF cycles the heat pump would steal more than 10C from the water tank during this night
So this solution is not feasible unfortunately. The only way to make it working in my opinion is to have DHW cycle disabledbefore AF cycle starts. This is of course hard to automatize because you never know when it starts. So it seems still the best solution is to use a relay to bypass it.
This is sad news. So that means we can only resort to adding a relay/ssr onto the dhw valve 3way tank direction wire to steal heat from the heating instead of from the dhw tank
It would be nice to have a easimy integrable box to allow for a maximum of people to fix this.
Or we should pressure samsung into implementing a fix to choose the heat stealing direction to use. But I higly doubt that this is going to be implemented at all.
Exactly. But I’m afraid an easy box would not be possible because to operate the relay properly you need to have information if the pump is doing standard water heating cycle or AF/AS cycle. This information you need to get from the pump with Modbus or some other integration.
Another possibility would be to have control DHW activation and heating schedule from home assistant exclusively. The goal would be to have DHW disabled all the time but water heating. Guess also not perfect solution and it still might not work because 3-way valve operation logic can be still the same so even with DHW disabled it the pump can still operate the DHW/space heating 3-way valve terminals in a same way. I will test it this night. I think it will work like this so then the only option is the relay.
So yes, best would be if Samsung implements this easy logic in FSV setting. By default keep the logic how it is but if installer decides to change this logic then give him an option. This should be there from beginning imo.
Thank you for trying and confirming this method did not work.
Yes, it would be great if you could also confirm if this method works or not. I think this would still be a viable method for those who only reheat their DHW once per day on a schedule.
In my opinion, the sensible thing to do would be to take water from the default position the 3-way valve is set (Room or Tank), as defined in FSV #3071, then the user/installer can choose behaviour by setting FSV #3071
But we all know it is very unlikely Samsung will make any changes to the logic now.
I agree. This would be really good and correct behavior. But as you said Samsung 99% won’t do anything about that. Stealing heat from DHW is not a good solution. I don’t know how Samsung thinks this is a proper way to do it. I mean like without the DHW tank connected do you have some other possibility? There is no 3-way valve so always the space heating circuit is used and nobody cares.
I wonder how other pumps like Mitsubishi or Daikin or Vaillant has this implemented. Does anyone knows ?
@SarahH you have good contact with Steve Maybe you could ask him if this would be possible? I mean programmer can do it in 5 minutes, right? I know chances are close to zero but sometime they could listen to their customers.
What I will do is ask my contact (Nick, not Steve) what the procedure is for getting a technical request (from a large number of users) routed to Samsung HQ, as the UK helpdesk are themselves fairly powerless.
Yeah, I think it will be like that. Sorry Nick, not Steve. Thanks anyway.
I fear the only possibility is to abandon Samsung completely and have a look for a vendor who listens to their customers But I think they will not bother with us because we are just a small group of geeks complaining all the time I know there are more important thing in live but gosh, such small stupid things drives me nuts. Maybe someone could try to reverse engineer Samsung’s firmware and do the change but it might be not easy.
I plan to install 120L buffer tank which I hope will help to smooth the operation a bit and maybe it will help little bit with this AF/AS grand theft of DHW
To be fair to Samsung, in a correctly designed system, the heat pump should never not be running for >60mins when the OAT is less than 5C, so this situation should never arise under normal operating circumstances. It happens for me as our 12kW Samsung is massively oversized for our heat loss so we turn off heating overnight as leaving it on at even the lowest setting would provide too much heat.
Do you mean volumiser? We have a 50L volumiser on the primary return. To be fair it’s not so much loss of heat as transfer of that heat from the DHW tank into the volumiser, so the ‘lost’ heat largely stays within the envelope of the house and is either lost to the property through cooling (same as would happen from the DHW tank) or is there in the system volume next time the system restarts.
Why? I use thermostat and from midnight until 6:00 I’m turning off the HP. I don’t need it to heat during night in case there is not -10C and below Or better I will decrease target temp by 2C so it will effectively disable heating until morning. During this time it makes 5 AF cycles and I can reheat the water in the morning. This has nothing to do with properly designed circuit. Don’t forget I don’t have UFH.
Yea, I mean volumizer. I have pretty low water volume in the system - roughly 40L or so so the system is very sensitive. Increasing the volume by 120l on return could help stabilize the system. But I’m not sure if it’s worth, would cost me around 400 eur.
And yea, I thought I’m buying 8kW pump. Only later I found it’s in fact a 14kW unit. This is my biggest grieve on Samsung because I wanted a smaller system so I wanted definitely 8KW pump, I could choose mamy other brands, even better but 8kW sounded perfect but I was cheated. And with all these stupid things I’ve described many times I’m really upset with this company. I would expect from installers they will inform me but no way, they didn’t know this pump has no internal water pump and I had to tell them. But now I’m much more clever so next time I will make a much better choice I hope
Oh, that’s fairly interesting, you suggest that if we consider “hacking” a 3way valve as 2 2way valves, we may end with a possible way to avoid DHW heat stealing.
Can you details the FSV for such configuration, just to be able to create a wiring/plumbing that is compliant with this possible solution?
2 port valve for hot water, wire brown to B17 and blue to B15.
2 port valve for heating, brown to B10 and blue to B15. Orange and grey wires are not used on these valves.
As far as I can tell, this configuration it will use the currently open valve’s heat source for defrost. That kind of makes sense as it is most likely to have usable heat within it.
This is technically correct. For a DEFROST cycle, the position of the valve(s) do not change - a defrost cycle will take heat from whichever circuit is active at the time the defrost was triggered.
However, here we are not discussing defrost cycles, but the anti-freeze and anti-seizure features of Samsung heat pumps. Not the same thing.
My system, a Joule pre-plumbed cylinder, is plumbed and wired differently. I think I have a 3-way valve for selecting Heating/DHW and a separate 2-way valve(s) (open/shut) for the heating circuit(s) (there are actually 2 heating zones available, each with a 2-way valve).
The 3-way valve has four wires (B17-20), 3 live and one neutral. B19 (neutral) and B20 (live) appear to be power, and then B17/B18 are switched lives to control the position of the valve (B17 ON, B18 OFF = DHW; B17 OFF, B18 ON = Heating). B17/18 operation are reversed if FSV #3071 is reversed from default.
I need to look more closely at the physical plumbing, as I think there may actually be 4 of those 2-way valves on a manifold, so the ‘3-way’ valve may actually be implemented via 2 x 2-way valves which each open or shut heating or DHW, respectively (which would be consistent with the wiring described above).
I also have a Gen 6 12 kW Samsung, but unlike yours, my AS doesn’t come on 24 hours after last DHW as long as there has been space heating in the interval. Perhaps a different firmware?
While I won’t hold out too much hope on this line of communication as I don’t think it will return much, it would be great if it does. I have a small list of things I could recommend that I don’t think would take too much to implement (completely on the MIM side) but could be great for users. I have spoken to Nick in the past when I had my PWM issue when my HP was first installed last year, so if you’d like another voice on the subject I’d be happy to help. However, I’m also wary of bombarding him or double teaming him.
Maybe you could ask him if this would be possible? I mean programmer can do it in 5 minutes, right? I know chances are close to zero but sometime they could listen to their customers.
