@SarahH Sarah, do you have any info about defrost operation values ? I can see sometime I have 1 - 3 - 7 and sometime only 2 - 7 so I wonder what this means exactly:
And here I have one correction. It’s below 5C and not 3C…
I think all is explained (rather unclearly) in this diagram from the Installers Guide, Michal:
Here’s my take on this diagram:
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Ts (the temperature you set on the remote controller) may be above or below the temperature at which you want the booster heater to cut in (Samsung call this THP MAX, set using FSV #3021, which can be anywhere between 45 and 55degC). Let’s assume you set THP MAX to 55degC (to minimise booster heater use). If Ts > THP MAX (say 60degC) then the left hand part of the diagram applies - the DHW tank temperature will cycle between (55 - #3022) and (55 - #3022 - #3023). If Ts < THP MAX (say 50degC) then the right hand part of the diagram applies - the DHW tank temperature will cycle between 50 and (50 - #3023) (i.e. #3022 is ignored).
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FSV #1051 is simply the maximum DHW tank temperature you want to allow (settable between 50 and 70degC), including use of the booster heater . The default (55degC) is aimed at tank sterilisation in a reasonable time - an hour or so judging by the picture you showed in your previous post - but if you are impatient and want fast sterilisation (and are prepared to pay the extra electricity cost) then by all means set #1051 at up to 70degC. When your DHW tank temperature hits the #1051 setting it will switch off the booster heater (and if necessary flip the 3-way valve back to its #3071 position).
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If you set #1051 below #3021, then the controller shouldn’t use the booster heater at all (but you’ll get a lower tank temperature).
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You can disable the booster heater using #3031, and even disable disinfection completely using #3041. (Disinfection has its own separate set of parameters - # 304*).
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Take no notice of “R410A” in the User Manual - the manual hasn’t been updated for the HTQ series, even though the Installers Guide correctly refers to R32.
The small temperature overshoot you see (1-2degC) is likely residual heat transfer from the hot tank coil after flow has ceased.
What about a sinple custom controller that
- When in DWH heating mode: Connect bottom sensor to heatpump temperature sensor input.
- When not in DHW heating mode: Connect correct resistor to heatpump temperature sensor input so heatpump does not enter it’s DWH mode.
- When top sensor (or thermostat) drops below setpoint: enter DWH heating mode.
- When bottom sensor above setpoint: Leave DHW mode.
Hi @Ringi, sounds like you’ve been walking your dog again…
Your idea might work but I suspect that most folk have only one DHW tank sensor (usually located near the base), learn how much temperature layering they get from what comes out of the tap, and adjust their cylstat setting accordingly.
My worry is that you can over-automate these things…
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Agree for people who get a reasonble turnover of their DWH tank, so can get good result reheating every day at a fixed time. Or who need more then one reheat a day.
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Thanks Sarah, seems I finally start to understand it 
Since I don’t need lot of hot water at the moment I think I could heat the water to 45C to get better efficiency and once per week do a sanitation cycle with a booster to 70C.This should keep any bacteria at bay hopefully. Definitely I want to keep booster heater disabled for normal operation and use booster only for sterilization cycle.
The last part to solve a riddle is #3011. What’s the difference between ON (1) and ON with hysteresis (2) ? This is also written in manual but I simply don’t understand it
I can put 3 sensors into the tank but I guess it’s overkill. Now I have it in the middle so I know that temperature at the top si tad higher than set temperature. I’m fine with all of this. The only thing I’m not fine with are those freeze protection circulation pump cycles for which the HP opens DHW circuit for exactly 6 mintues and steals my precious hot water from tank for no reason Thing is the pump would need to be without electricity for some good amount of hours to freeze so this pump circulation every hour is just waste of resources. I just want that pump will not open DHW circuit for this. Maybe I could add some relay to keep the power to valve disconnected in case there is no real need for heating a water… This could work I guess. The pump would think it is opening the DHW circuit while relay would ensure it is not… I have one shelly 1em switch somewhere so probably worth a try ? This is a little bit of overengineering but I guess there is no other opinion since Samsung is not giving a choice.
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I expect Samsung is partly trying to prevent freeze protection values from operating, these operate at a few degree above freezing. (I expect the person who wrote the software would rather all their installations had their buffer tank setup.)
Don’t forget that this only kicks in when it’s colder than 3 (or 5?) degC (I know Slovakia can get much colder than southern England, but maybe this is still not that often). So maybe it’s not worth getting an ulcer over, though your idea of defeating the 3-way valve switchover with a relay might be worth a try if you don’t mind taking the risk…
Beats me - I’ve read the manual 10 times, and can’t see any effective difference between #3011 = 1 and #3011 = 2. Perhaps you should ask the Helpdesk now you have a contact name?
Seems to be 5 degrees but I will observe. But you are right, maybe it’s not worth the hassle since the temperature is bellow 5 maybe 60 days in a year, maybe less. We don’t have that much different climate at the end (besides rainy days )
I’ve found this in the manual but unfortunately don’t understand it so maybe you have a better understanding ?
Maybe yes but I would still prefer a switch in the settings. I swear I read some stories where users had a buffer tank and the pump still took the heat from DHW because the temperature was simply higher there… As I said, before I had no DHW tank and it also was doing these cycles but with CH circuit and it was not an issue at all. I haven’t noticed any radiator temperature drop at all and the temperature dropped maybe 5 degrees below indoor temperature so I had 18C in radiators. Since water is not circulating after 6 minutes the rooms is not cooled at all… Simply it was much better than it is now and what is worse I simply can’t change this behavior in a nice way.
The Installers Guide has a diagram for each of #3011 = 1 and 2, but they look almost identical; the only difference I can see is which part of the on/off cycle the control starts at - once the cycle is going both settings seem to have the same effect.
Hopefully other forum users (maybe those with a legal background) can better untangle the fine print in the manuals 
…
I have been following this thread about DHW heat loss with some concern but then I realised that the defrost/freeze protection on my old style (and cheap) indirect hot water tank with coils at the bottom cannot waste heat like this.
The coil is at the bottom and the hot water has stratified to the top so the water used for freeze protection is only 20 deg or so not 50.
Why are the mcs approved water tanks designed with coils all the way up?
My resuse of an existing indirect tank works fine with the Samsung HT. It does seem that the current plant room tank is overcomplicated for a high temperature heat pump like the Samsung HT.
It is offered as a simple flame boiler replacement solution is it not?
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I don’t know, HT is because it should be able to deliver 70C flow temperature without additional heater. I still need to test the max capability of this because with water heating I’ve reached 61.5C max. but it was probably because the water reached the set temperature of 50C in the middle of the tank. I will try to crank it up to 55C and then I guess I will be close to declared 70C flow temperature.
Why coil is all the way up I have no idea but thinking of it now it’s just a shitty design. That top part is kind of useless without circulation. I have a port to connect circulation pump but this is in the middle so not sure if I should connect it to the top for hot output water or down to input water. Would need to connect another pump so now this become too complicated.
I mean it all works I only hate those anti-freezing cycles stealing the heat from DHW tank.
I can understand your frustration. In time the DHW plant room systems will have to be greatly simplified to make them affordable to everyone. High temperature heat pumps (60C+) have the potential for a much simpler boiler replacement and DHW delivery. I fitted the 8kW Samsung HT for a similar cost of an oil boiler and tank with no grants.
{bit off topic - maybe a separate thread is needed}.
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Right… HP is far best source for heating your house. Prices goes down and if you have infrastructure ready replacing a monoblok is matter of hour or so. That’s why I went with monoblok and separate DHW tank. I hope this one will last 10 - 15 years and then I just buy new for 3K and I’m good to go for another 15 years.
There is no problem for this pump to heat water to 55C while flow temp is 65C, probably it would be able to heat even bit more but still it’s not enough for sanitation cycle if we consider stratification.
And maybe this fear for bacteria is a bit overrated in home conditions. My problem is I don’t know what is minimum turnover which is safe. How long I can keep the water in tank unused ? E.g. holiday. Days, week or two ? I think nobody know and it’s just a guess. If we consider than in UK around 600 cases were reported a little bit more than half in community, the chances are really really low because I can imagine those cases results from households with very poor conditions where no one take care about legionella at all. This is 300 cases per year which is literally nothing… From 28.4 million households 300 is 0.001056%. This is incredibelly small. So I don’t know what to think about that. I would keep my DHW at 50C and this would be probably safe but stratification is maybe a concern as there could be 40 - 45C at the bottom which is quite ideal for growth. So still don’t know what to think about this legionella scarecrow
I consider avoiding stagnation is much more practical than trying to sterilise an entire tank with high temperatures. A simple domestic tank that is purged every few days should not be a significant risk and I do not worry about it for my family.
I am, however, worried about a guest room shower with stagnant water in pipes and shower heads and ask it is flushed through before anyone uses it.
A large coil area gives better COP when heating a tank from cold, I expect the energy regulations ignores heating a tank that is already half filled with hot water. Fitting a large coil in the bottom of a tank requires a double coil that is more complex to make with existing automated factories. So most “heatpump tanks” have coils that take up much of the height of the tank.
Many people care about “recovery time”, a fast reheat from a empty tank needs a large coil or high flow temperatures.
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Yeah, I can see it the same way. I assume my tank is flushed at least once or 2x a week so probably this is not big issue. I’ve never thought about guest rooms in hotels about purging the lines lol. Only when I start to read about this I found as it could be pretty a bigger issue. Some rooms might be not occupied for weeks with stagnant water in lines.
This is a problem because the tank is empty only at very beginning and then you only maintain dT around 10C… With high turnover after bath or showers delta is maybe 20C but still far away from tap cold water entering the tank…
Maybe I should have kept my old electric boiler to save the hassles. I hope during the summer COP of DHW will be at least 3. Now it winter it seems it’s around 2.
We only need 50c in the bottom for a few hours overnight once every few weeks. The 50c water in the top 2/3 of the tank must go somewhere when it is replaced with 60c water. So a probe reading 60c 1/3 up is considered good enough. A flow temperature of 65c for long enough should be able to do this.
But a simple emerson heater 1/3 from the bottom gives such a good backup when a boiler/heatpump fails, so why not use it once every few weeks after the heatpump have done it’s full reheat?
(I don’t believe sanitation is needed in small tanks that get fully turned over most days.)
Hi thanks yes that makes sense and confirms to me that recovery times using the existing DHW tanks with small coils are ideal for high temperature heat pumps. The current mcs approved solutions imo are too expensive and disruptive for most home owners and need a major rethink.
Most infected people will not get tested even if they need antibiotics in hospitals. So we don’t know how many ramdom people are inflected.