“The new EHS Mono HT Quiet is able to consistently provide hot water of up to 70°C for domestic heating purposes.¹ This can make it a suitable replacement for gas boilers, as they provide a high leaving water temperature. With its strengthened parts and an extended Oil Groove, the new Scroll Compressor can compress refrigerant at much higher pressure, while Flash Injection Technology increases flow of refrigerant. As such, the compression ratio has increased from 13 to 17.²”
1 Leaving water temperature, when the outdoor temperature is between -15°C - 43°C. Results may vary depending on the actual usage conditions.
2 Compression ratio = Discharge pressure/ suction pressure. Based on internal testing on an EHS Mono HT Quiet outdoor unit, compared to a conventional EHS outdoor unit.
Well that’s great so I’ve bought this heatpump… I connect external DHW tank only to find out the max. temperature I can set is 55C and disinfection mode is possible only with booster heater connected. WTF ?
I’m bit of disappointed and don’t understand why if the pump is able to provide hot water until 70C for heating why it can’t supply it also for DHW tank ? In manual they says disinfection mode is supported only with booster heater connected so now I have a high temperature heat pump and need to install additional booster heater to my DHW tank so I can increase water temperature to 70C for disinfection.
Why Samsgung, why ? This is a big fail. Or am I missing something ?
As the risk of disappointing you further @Michal_S let’s make sure we aren’t missing something obvious.
What have you set FSV#1051 to? I ask because the default is 55degC but the manual says you can set this up to 70degC.
I’ve just found on another forum that yes, I can change this in #1051. Now I have indeed 55. But at the other hand I found the user said he can’t reach 60C without booster heater but let me try it. If it will work I would revoke my disappointment statement but I’m afraid 70C will be impossible because I guess for such temperature you would need flow at 80C… So indeed I guess 70C without immersion would not be possible but probably it’s not HP fault but my misinterpretation of #1051.
What DHW settings do you use ? I still I don’t understand fully how it works. When you enable DHW mode there is 0,1 and 2. 0 -off, 1- on, 2 - on with some hysteresis. Then you have max. temp #3021, stop #3022 and start #3023. I did not understand from manual how this works so if you would know and could explain in some examples I would be grateful. Also what is this max. temp ? because max temp is set also in #1051 so how it correlates with #3021.
There’s a bit more information in the Installer’s Guide (but not much).
I never heat my DHW above 40degC so I haven’t studied the matter too closely, but it does appear that above FSV#3021 setting the controller switches the booster (immersion) heater to complete DHW heating. And since #3021 has a maximum of 55degC this may be your limit without a booster.
There is one trick that you may want to try, though. According to my marginal notes, #3022 is effectively “overshoot” which can be set as high as 10degC. So if you set #3021 to 55degC and #3022 to 10degC you might get your tank up to 65degC without booster heating.
Thanks, that make sense. I found those manuals really bad and I consider myself as not totally stupid
Really 40C ? Aren’t you afraid of legionella ? This is pretty low temperature for a tank, your turnover must be really high. What volume do you have ? I don’t know what to think about this legionella thing. Sometimes I think it’s real thing the other time I think it’s overrated in home conditions. So I’m not sure to what temperature set DHW tank. I have 280L and bought it just because before I had 120L electric boiler which I’ve used with 70C water. And was sufficient, but to have some buffer I took bigger thank but even at 45C water the turnover is up to 50%. Often 25% and some days it could be close to zero. I bought bigger to use it with lower temperature but then I’ve read about this legionella thingy.
This trick sounds interesting to me. I will give it a shot. So if #3022 is overshoot what is #3023 ? E.g. what happen if I set this to 5C ? And you said if I set #3021 to 55C… But then what do I set target temperature for ?
E.g. I go into DHW setting in roomstat and set standard mode and temperature to 50C. I thought this is the temperature the pump should heat the water to - a target temperature. So what happen if I set e.g. #3022 to 2C (overshot you say) and #3023 to 5C ? I thought it means that it starts when the water is TARGET_TEMP - #3023 so in this case it start heating the water when it drops to 45C and then heat until TARGET-TEMP + OVERSHOT = 52C… But seems I’m interpreting this wrong because it does not behave like this. Also still #3011 is mystery for me. Now i set it on with hysteresis but no idea what it is doing.
A bit simplistic maybe but the critical pressure & temperature of R32 is, (I think), 57.83 Bar.a & 78C, the properties I’ve had a look at don’t seem to go beyond 44.437 Bar.a & 65.6C, this means theoretically, that a 17:1 PR compressor discharge temperature would reach this 65.6C (at 100% compressor efficiency??) from ~ -30C & 2.61 Bar.a so around a outside air temp as low as ~ 15C. This Samsung PR of 17:1 seems massive, I thought around 5:1 would be more the norm which might mean that 65C discharge temperature might only be achievable at a outside unit evaporating temperature of ~ +3C and a ~ OAT of maybe 5/10C?. The compressor efficiencies will be a big factor in this though and a PR of even 3:1 might still achieve ~ 50C discharge temperature at a compressor efficiency of 80%, from a evaporating temperature of 3C
Welcome to the community These are indeed some nice numbers. The highest flow temp I’ve seen for a short time so far was 60.5C which is close to your theoretical maximum. Not sure if it can go a bit higher but at this flow temp the pump consumed 5.8KW of electricity which could be the max. of this pump. The temperature here was around 0 so wonder if in higher temps it could go higher. With 60 flow temp I guess max. DHW temperature could reach around 55C. But I guess it still could go higher since Samsung declared 70C of flow temperature. I’m yet to test it.
This is still not enough for disinfection cycle though so seems heater booster is really the only option.
Depending on the coil size of the DHW tank, the placement of the coil, and placement of tank thermostat, it is possible a flow of 70c will not give a reading of 60c in the tank. It may also take longer then the default maximum time the heatpump will remain in DHW mode.
That’s right. Seems this requires lot of time to find it’s maximum and everyone’s system is different so it has to be fine tuned case by case. I have coil with surface area 2.9m2 so I would say kind of average.
From my last run it was heating 280L from 45C to 48.5 (middle of tank) in 27 minutes reaching flow temperature of 53.5. so dT = ~5C which is not so bad. That time it’s not great though I would say.
In any case I would say it’s not good to torture pump like this and is better to buy a cheap 3KW immersion heater to do sanitation cycle once per week and keep the tank temperature at 48C.
It only requires 2.53kw (power) to heat 280L from 45.0C to 48.5C in 27 minutes, the trend shows a temp rise (between 1051&112hrs) from ~ 45C to 48C, say dt 3C in 27 minutes = 2.79kw, the water out temp/HW temp dT is ~ 6C so why does a 2.9m2 coil only emit apparently ~ 2.5kw?
Excellent contribution @Johntheo - a great first post .
But there are a couple of issues which may complicate matters:
The heat pump condenser is countercurrent, so LWT is set by its approach to the (typically 15-20deg) superheated compressor discharge, which can be well above the refrigerant critical temperature.
The controller sets discharge pressure such that refrigerant condensation will be complete at RWT (not LWT), (though minus a couple of degC to allow for a finite temperature approach at the condenser exit). So it appears to me that the difference between LWT and RWT (i.e. water circulation rate) can affect the maximum achievable LWT.
There is some evidence that the refrigerant is not pure R32 - the saturation pressure at the compressor discharge as reported by the controller is 2-3bar higher than I see on the pressure-enthalpy table for pure R32. I speculate that this is due to the presence of compressor oil, which we know is R32-miscible. I believe the oil is injected into the R32 at the suction to seal the compressor clearances, and not all the oil is separated at the compressor discharge - some stays with the R32 around the circuit and exerts a vapour pressure. If I remember Dalton’s Law of partial pressures correctly, this suggests that there may be of the order of 5mol% oil in the R32 at the condenser - enough to affect its condensation properties (to the extent that I can’t use pure R32 charts to predict saturation temperatures.)
I should emphasise that this last point (oil injection) is highly speculative - I can’t check without whipping the lid off the Outdoor Unit to look, and I can’t do that because it’s on an elevated platform and I have no head for heights…
The energy required to raise 280L of water from 45C to 48.5C is, 280*(48.5-45)/860, 1.14kwh, this took 27 minutes so the coil power required is 1.14*60/27, 2.5kw, the coil dT would be 7.25C at a flowrate of 5.0LPM, 3.63C at 10.0LPM & 2.42C at 15LPM. I would expect a 2.9m2 coil to emit well over 5kw even at that coil temp/Hw dT temp of 6C.
Have you a trend of the HP data for those periods, assuming cylinder heating only?
20C superheat would mean a R32 compressor temp of (78-20) 58C & 37.5bar.a, this scroll compressor has a PR of 17:1 so the maximum evaporating pressure is 2.2bar.a & -35C. At a evaporating temperature of say 0C, 4.4bar.a, this scroll compressor has fixed?? PR of 17:1, allowing 20C s/heat then the max discharge pressure would still have to be ~ 37.5bar.a, a PR of 37.5/4.4, 8.5:1 but at a PR of 17:1 would be, 4.4*17, 74.8bar.a, how does this work then, is it just a waste of compressor power unless the evaporating temperature is down around -35C??.
Total heat output 4.2KW. Flow around 19l/min. Max flow temp. 60.5C
There is no circulation pump in DHW so I guess stratification takes it toll but anyway is this really unexpected ? That COP sounds pretty normal at ~0C outside and those flow temps.
@Ringi the temp sensor is right in the middle of the tank. Could be it is not in the center though. But from the screen you can see the coil is from top to the bottom. input of flow water is at the top, return bottom. I have 1" cooper piping but Max. flow is around 19 - 20l. I suspect there is some pressure loss on TF1 filter I have installed on return.
But something is really strange because from what I computed then heat needed to go from 43 to 51C is 2.61 kWh while emon shows 4.2KW was delivered. Also it would take around 9 minutes to heat this so no idea why mine took 27 minutes…
These are indeed some nice numbers. The highest flow temp I’ve seen for a short time so far was 60.5C which is close to your theoretical maximum. Not sure if it can go a bit higher but at this flow temp the pump consumed 5.8KW of electricity which could be the max. of this pump. The temperature here was around 0 so wonder if in higher temps it could go higher. With 60 flow temp I guess max. DHW temperature could reach around 55C. But I guess it still could go higher since Samsung declared 70C of flow temperature. I’m yet to test it.
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