Heatpumps will get a bad reputation if they can’t cope with all members of the household having baths after each other.
We have no issue living with a tank that needs a 30 minutes boost between the two of us having showers, but if we did I would set the tank to a higher temperature. But many people would define our home as a 4 bedroom property! So should a system that will not work for the next resident be funded by the government?
Yes that’s right unfortunately heat pumps are having to compete with the combi boiler with its endless supply of hot water, although it was not always like that but no one wants to go back to waiting for a shower these days.
Untill we can have a 20kw heatpump that will modulate down to 3kw with great anti cycle control we can’t get a true combi experience.
The Heat Greek Mini Store will get close but will never give the best COP. (It would also fit above my bathroom ceiling, so give very short pipe runs. However seems costly.)
Personally I have no issue with heating a tank to 60c overnight on cheap rate with a COP of 1 and a boost bottom to reheat to 40c if required. (Or just reheat top of tank.) So doing the same using a heatpump with a COP of 2 seems OK.
Hello Michal
We installed our 14kW model this year with exactly those words re up to 70° sealing the choice. As it was being installed, the engineer said dhw could only be set over 55° if Samsung changed some setting. I read the manuals many times until I could somewhat understand the peculiar English.
We have an 800l heat store from which both the underfloor heating and the dhw are supplied. This has a 9kW 3ph immersion heater roughly half way up the tank. We had this linked, via a relay, to the heat pump control to act as a booster when required, which I also thought would get us past the 55° ceiling. This has never worked, even when I attempted to force it.
Anyway a stroke of luck meant that the sensor for dhw was accidentally not replaced in tank after playing about changing height within the tank. By having no feedback, the HP just keeps running, getting up to 67° in the top of the tank if we let it. So if you want to, you can get the dhw up high, simply remove the sensor for as long as needed. (It doesn’t work to disconnect the sensor at the control - you get an error message. I haven’t, yet, tried a switch on the sensor wire - I think it may flag an error. )
This is not the most efficient way of using the HP, I know. But it does allow us to get enough hot water for baths, via a spectacularly poor Slovak hot water system. In the event that there is spare, the ufh can use the heat from the water in the top of the tank/heat store to top up.
Sorry for the lengthy post, but it works, although here in northern Slovakia we’ve only had a few nights this winter so far below -12. The next two months will show what’s what!
Ahoj 
Do you live in Slovakia ? You seems to have pure English name
800L heat store wow. In northern Slovakia it’s much more colder during a winter than in Bratislava region so a big buffer tanks is reasonable. What’s your SCOP ? This winter I haven’t seen more than -5C yet.
With help of guys here I’ve already understood how the pump works together with DHW tank connected. Took a while
You really can go up higher than 55C as you’ve said with this cheat to fool the pump. As Ringi stated you can connect a resistor which will effectively decrease the reported temperature or you can simply put the sensor at the bottom of the tank. That way you will have 55C max temp allowed at the bottom and probably 65C at the top. This could be pretty effective against legionella I guess since at the top it will be eradicated and at the bottom dormant. With regular turnovers this possesses no risk in long term in my opinion. Also yes it is not most effective to have a flow temp close to 70C but it is still more effective than immersion heater especially in case you need to use it once per week.
This way probably a booster heater is not needed. Anyway, if you have 9KW booster you really can activate it but you need to increase #1051 DHW max temperature on remote controller. Here I can go up to 70C. So then the pump compressor is heating until 55C (max. temp set in #3021) and from 55+ the booster is running (You also need to enable it in #3031)
So I would say the title of this thread is now answered. What I’m more nervous of is this heat stealing from DHW for anti freezing cycles. This makes me sick and there is no easy way to prevent it besides some hardware hacks or keep running space heating overnight.
Do you have your pump on emoncms ? What pump exactly do you have ? You may check mine here if you are interested but it is still in tweaking mode.
https://heatpumpmonitor.org/system/view?id=544
Btw, what do you mean by “spectacularly poor Slovak hot water system”. I’m pretty sure than in some parts of UK the hot water system might me much worse than here haha It depends on the property and owners. Heatpumps are mostly installed in new detached properties where owners are educated so I guess water system is such properties is on a good level. Old rubbish hotels without too many guess I would be afraid more
Sorry to butt into the conversation here with my first post - got plenty of other questions but will post elsewhere on the forum. We had a 14kW Samsung heat pump installed a few weeks ago, replacing an ancient combi boiler. The engineer set it to do the legionnaires boost to 60 degrees once a week. The rest of the week I am happy to have the DHW set to 47.5. Are you suggesting this is a risky strategy?
Do you have an immersion heater connected ? How big is your turnover and what big is your tank ? If you don’t have circulation then because of stratification the temperature across the tank will be different. Where do you have temperature sensor placed ?
E.g. if you sensor is in the middle you will have 60C during disinfection in the middle and at the bottom it can be easily 55C or lower.
Risky I don’t know, I think if the tank is purged at least once or twice per week it is not possessing an issue. Before DHW I never thought about bacteria to be honest. It is still like some imaginary enemy where risks are very low but of course people worries naturally about it to protect themselves and their families. It’s more an issue for an elderly or sick people.
I expect you need to switch in a resisters of the same value as the sensor gives for the temperature you want the heatpump to think it is.
Or for a thermal store, just pretend it a CH zone, set fixed flow at 75c and remove the “call for heat” when you got as much heat as you want. Put in silent mode if want higher COP in exchange for lower output.
Good idea. I’ll put it on the list… 
Ahoj Michal! Yes, we live in Ždiar. We usually get a week every year of -18 to -25. Only lived here fulltime for 8 years, but even in that time the super low temperature days are getting noticeably fewer. Oh, and not English - Welsh! 
(Cymro = Welshman!).
No, we haven’t got accurate measuring yet. But last December we used 6.25 MW of electricity and up to end yesterday this December 3.07MW. We’re hopeful for a payback in the installation of less than 3 years.
By the way, the engineer wasn’t too happy about my DHW work around - “ you’ll get less than 2 COP!” “That may be so, but it’ll still be better than the 1 we had with the immersion heater!” Which took him aback rather, but he admitted I had a case!!
The hot water system 
. Installed by the people who renovated our 1912 log house, the hot water system has a circulation return. Not so popular now, as unless the insulation is excellent you basically just throw heat away. Not a total loss if it is kept within the living envelope, but this is poorly insulated and close to the roof. So I switched the pump off. Not much difference - as I then discovered that the main supply goes via what should be the return circulation pipes. Anyway, that’s another job on a list that runs to 3 volumes…
On the issue of doing a defrost cycle when in dhw mode, I made the same point a little while ago in another thread. Especially when the defrost seems to start within a few minutes of the dhw mode starting up. I do wonder if this is because the dhw mode requires increased heat production and that increase causes the fins to ice up. If it therefore inevitable, then it would be better to switch the valve back to heating mode, fo the defrost, then switch back. Then the heat for defrost would come from the heating system, not the hot water system. Not too difficult a programming change I would think.
I’ve got a 200 litre tank with temp sensor and immersion at the bottom. Two to four person house, showers first thing and last thing depending on occupants.
It’s interesting to see a Welshman in Slovakia I could imagine an opposite.
In Zdiar it can go very cold but 6.25MW per month ??? You kidding. Everything is better than immersion heater but at the other hand immersion heater is cheap af so even you have heat pump payback can be longer, especially with COP below 2.
Circulation is a good thing but yes it can waste heat, at the other hand you have hot water instantly. In my house without circulation I need to wait a litre of two until hot water starts to flow upstairs.
But actually this is killing me with DHW and this Samsung pump…
At 10:00 I’ve re-heated the tank to 50C and then barely used the hot water. But then at 17:00 thermostat turned off heat spacing and exactly after an ONE hour (just before I wanted to heat space again) this STUPID anti freezing cycle started, opened 3-way valve to DHW and took 5C from my HDW tank which dropped below 45C and immediately triggered the re-heat of tank again to 50C. As this is not enough, there was defrost cycle triggered as well. Now tell me this is not frustrating, basically I’ve lost all the energy I’ve put into a tank at 10:00! How a stupid circulation pump running for 6 minutes can steal 5C from 280L tank ??? Nonsense…
The pump should circulate the water over the CH circuit and not touch DHW but no, I can’t achieve that. Extremely frustrating.
When the pump is idle the flow and return temperatures are decreasing. Pump registers is but only at input and output of the pump. The water within pipes inside your house is still warm. So it thinks it needs to reheat so it start circulate the pump. This would be OK if not that stupid pump open DHW circuit to steal heat from it. A week ago I did not have a tank so of course it has no other possibility only to run the pump through CH circuit but it was absolutely OK. I even didn’t notice it but now I hell notice the DHW temperature DROP.
Yes, I’m with you on this! Luckily the large buffer we have means that after the 5 minutes or so of defrost, the top of the store has returned to the initial temperature within about 10 minutes. It seems that if the outside temperature is above about -1, -2 then the hot water gets to about 45 no problem. But in our system the ufh is pumped independently of the heat pump, so continues to take water from the heat store. If there is a big heat demand this interferes with the flow within the heat store and there seems to be some sort of chaotic mixing. This prevents the dhw heating properly. If it is at a time when we need a bath, on occasion I have switched the ufh heating off, which allows the dhw to achieve the necessary temperature. I think we will need a small (250-400l) dhw tank so that we can run the dhw at a lower and more efficient temperature. But I’d still like to use the heat store principle with cold water running through a coil in the dhw tank to get warm. Then we don’t need to worry about Legionnaires at all.
Regarding the electricity usage - the house is about 320sqm built area, 500 living. Our heat loss calculations 18kW.
Štastný nový Rok!
Just looked at the graph more closely - your defrost takes an HOUR ??? No wonder you see it as a problem!
Wow, this is really a big house and crazy heat loses. So good you have switched to the heat pump
Nono, the system was in idle for 1 hours because there was no need for space heating or DHW. But this is some stupid Samsung implementation that after an hour if the outside temperature is below 5C it will run the circulation pump for 5 minutes and opens DHW circuit. So the heat is taken from the DHW tank.
Defrost takes only 3 - 5 minutes (second line in chart) and this is done with source which is active at that time. Defrost is not an issue. Anti freezing protection is because this one is running every hour if pump is not active. Before I had DHW tank it simply run the pump for 6 minutes and water circulated in CH circuit and no issues. Now it explicitly opens DHW circuit (look at the 3rd line chart) and takes heat from that. It there is -5C it can take 5C per single antifreeze run. Once antifreeze is completed in 6 minutes then it again close DHW circuit like nothing happen. Ridiculous implementation.
Stastny novy rok aj tebe
Sarah has recently posted on the same issue Samsung R32 ASHPs - when is a defrost not a defrost?
Our HP runs for long periods as the heat demand is high. At least cycling isn’t an issue! But if the ufh control system registers all zones satisfied then the ufh powers down and everything goes quiet. Now this doesn’t usually last for long, so I don’t think the antifreeze protection kicks in much, if at all. EXCEPT when the zone night setback temperature reductions occur. This is often accompanied by a switch off of the HP, as the zones are satisfied. Elec use can be starkly reduced if ambient temperature is above freezing. But not nil… and I have been wondering why not. This protection run maybe the cause - and would be the reason for previously unexplained low temps in the dhw area of the tank, when they shouldn’t have done. I thought it was poor stratification of the heat store - but this frost protection would cause that. Why would Samsung run it from the dhw? And why is it not possible to change it?? 
And looking at yesterday’s 1/2 hr elec use:
Those spikes in the early morning could well be this protection.
Exactly this is the issue. NO matter what if you have DHW enabled in field settings it will take heat from there during anti-freezing cycles which happens always when outside temp is below 5C and pump idle for more than hour and then they repeat in every hour interval. Pathetic…
This picture is form when I had no DHW. Circuit temperature drop is totally negligible during night. With DHW it is doing every hour taking heat from tank and causing unnecessary load on heat pump and components, noise, etc…,
I guess the price you have wrong. 102kw costs at least 15 eur… Did you include distribution fees ?
That’s bare unit cost ( print from supplier’s app) I usually double it for actual cost to us.
