Samsung EHS mono 5kw settings

beginner here, who just installed Samsung 5kw mono.
I am using it for DHW so far.

Does anyone have some useful beginner settings please, where should i start?
The tank is 150L. When it is heated to 40C it covers our evening showering without problem.
But after that it needs to be heated again so we dont have cold water in the morning.

Do you suggest to set any schedule, different temperetures?

One strange finding i have so far:
In DHW setting → Heat Pump → 3021 Max Temp. i set 45C.
But when i check just after the heat pump finished heating the tank to 43C it showed output temp 56C.
Do you think this 3021 Max temp is being ignored or it is used for something else?

Hello @lukso

Setting a schedule for the DHW reheat is often a good idea. E.g rather than have the heat pump heat up the cylinder straight after the shower, have it wait until 2-3am to do the reheat at that point. Potentially lower tank losses, though perhaps offset by lower COP if it’s colder overnight? In general it’s more efficient to try and heat up the tank after 50-75% of the hot water has been drawn off, rather than lots of short top ups.

FSV 3023 sets how many degrees the tank is allowed to drop before the HP reheats it. The default is 5 degC so the HP will kick in as soon as the tank drops 5C below the set point. I would recommend increasing this to maybe 10C or more? The colder the tank is the better the efficiency of the re-heat will be.

And or setting a daily schedule for DHW as @TrystanLea suggested is also a good idea. When setting a schedule for DWH you have to specify a ON and OFF time as two separate entries.

I would also recommend increasing FSV 3032 which specifies how long a DHW cycle can run before the immersion heater kicks in. The default setting is 20min, I would recommend increasing this to 60 min. If you’re only heating to 45C the immersion should never be required. The HP should be able to heat to 50C/55C no problem without the immersion.

I think you’re looking at the flow temperature? A flow temperature of 56C will result in a tank temperature of about 45C

Here’s a slightly rambly video of the settings I use on my Samsung ASHP:

Here’s a video of the performance of my Samsung ASHP:

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Thanks Glyn for the settings. Your videos were big part why I chose this heat pump when I found it on second hand market.

This weekend I finished installation and connected it to floor heating as well. I will start with your water law and flow temp recommendation.
In floor there is 6 circuits 80m each.
Flow meter is showing 14lpm when floor heating and 20lpm for DHW on lowest Grundfos setting with 100% pwm.

I also used caleffi antifreeze safety valve as no glycol is in the system.
We don’t have strong winters where we live in Slovakia, but it can go to -10C on few occasions.
Do you think this pump has any software freeze protection… something like starting pump based on flow temperature getting close to 0°C when heat was not requested by thermostat nor by DHW for prolonged time?

Nice work, sounds like you’ve got a good setup.

Yes, when the outside temperature drops below freezing and the heat pump is not running it will momentarily take a little bit of heat from the DHW tank and pump it around the system to keep the water from freezing.

This is what it looks like on our monitoring, the compressor is not running so it only uses about 75W of power, this is just the power used by the pump.

This is a very small amount of energy, it doest have a signifiant impact on the temperature of the DHW tank.

Sending some photos of my install with 26mm pex tubing.

Just wondering… have anyone used the Samsung WIFI kit? Is it useful, does it allow any control over cloud and mobile app?

Nice work, I’ve got the Samsung WiFi gateway and app. The app is very basic, but it’s very useful to switching and unit on/off and adjusting the temperature when away from this house. This is very useful when returning from holiday to switch the heating on before getting home. It’s also shows energy monitoring data:

hi glyn

thanks for this video! I never knew there were heating timers on this unit and I think most people aren’t aware of them either, they are not publicised. I’ve been playing with home assistant sending modbus commands, and my pre-existing external thermostat timer system, to try and do a “boost” to 22-23C during the octopus offpeak period. Its a bit of a faff and not family friendly!
You may well have made my life a lot easier! I’ll cross post this onto renewableheatinghub as well if you don’t mind?

also can I ask you what values you have for DHW, in 3011, 3021,3022, 3023?
I have (respectively) : Use(hysteresis), 55, 0, 30
my desired behaviour is it should only come on if the temp is below 25 (55-30) then reheat in full to 55, as I want to only start a heating run with a cold tank , efficiency as I’m sure you know is loads better.
the behaviour I’m getting is that it comes on if the temperature has only dropped a few degrees, so I am having to using timers so it doesn’t come on unnecessarily. I have RTFM but it doesn’t seem to make sense…
the immersion is not connected in any way to the HP , only via the PV diverter which isn’t in play at all at this time, and DHW on the HP in standard mode.


3011: Use(hysteresis),
3021: 55 (but I use Eco mode so it only heats to 45C)
3022: 0
3023: 5

I heat DWH on a schedule, I’ve got two schedules per day to topup water to about 40C - 45C. I’ve only got a small 150L tank and we use a lot of hot water. Kid has a bath every day and usually two showers plus washing machine and dish washing all uses hot water. Yes, the colder the tank the better the efficiency.

I use Eco mode to avoid the immersion being triggered, not an issue for you if it’s not connected.

I set 3023:30, which to my reading of the manual should mean don’t reheat unless temp <= 25. But what actually happens is that it reheats after only a small temperature drop if set to always on, so the only way to defeat that is with a timer. interesting that you ended up with a timer as well. In your setup testing did you find that changing the value of 3023 actually works?

also regarding your heating scheduling its interesting to me that I think you are effectively using WC mode to give you a fixed LWT system because your WC line is basically flat? So your system will govern your IAT by balancing system running or not, against target IAT. and you can achieve a higher IAT by running for longer.

whereas in my (and most) systems to achieve a higher temporary IAT, one needs to make it run a higher LWT, which with the system in WC mode can’t be done. I’ve been trying to work around this with fixed LWT mode with the LWT controlled by home assistant according to the WC line, plus/minus “boost” inputs, but not proving easy to get right / stable.

Sorry, I never tested this. I like having control over when the DHW cycles run. Are you sure your tank sensor is in the right place? Could your sensor be in a low pocket?

Yes, I’m not really using WC, pretty much a fixed flow temperature seems to work fine for my system with oversized radiators. What ever the temperature I don’t need higher than 35C flow, and I’ve found that running lower than 30-35C flow results in lower performance. Correct, the system switched on/off based on IAT, if I need higher IAT it runs longer.

I guess this works for me since my 5kW heatpump is about 30% oversized for my house, so even running 35C flow temperature is enough to re-heat the house from cold if needed.

I think the way most Samsung installs achieve this is by using a third party thermostat to control the IAT and running the Samsung controller in WC mode based on LWT rather than IAT. The Samsung controller then provides a display to increase or decrease LWT by a few degrees e.g

Agree, the Samsung controller is very simplistic. I’ve recently installed a Vailltant Arotherm+ system, it’s quite impressive how it can do parallel WC curve shifting to temporary increase LWT to achieve a higher ITA

I have sensor 1/3 up from bottom, but thats not the point. 3011=use hysterises, should mean that DHW would refuse to run unless tank sensor <= (3021-3023), but I find that value of 3023 isn’t having any effect. if you didn’t test , doesn’t matter, I’ll perhaps contact samsung tech support.

separate stat for the IAT, with the controller doing LWT WC, is how I am using it at the moment. The “separate stat” is actually a relay thats closed by home assistant / node red logic. But the LWT change is only do-able by pressing those buttons as per grahams video - unless you’ve found a modbus way to do it?

In my short experience FSV 3023 is actually only DHW setting that matters. All the other 302* values are mostly some kind of user interface limiting parameters.

Right now I have DHW set to 46°C and with 3023 Start temp at 7°C it means it starts reheating at (46 - 7) = 39C.
I tried both DHW ON and ON with hysteresis and haven’t noticed any significant difference. My temp sensor is close to top of the tank and once it shows 39C it gets lukewarm pretty quickly.

When the pump is heating DHW it looks like running full steam ahead no matter what setting I use.
When closing those 46C it is using 2kW with outlet temp 60C and inlet cca 57C. It takes around 30minutes and 1,1kWh to heat our 150l tank. That happens twice a day usually.

I don’t use DHW scheduler as I found it doesn’t take actual temp into account and started reheating even when water temp was near the set temp.

Last weekend i played with cables and rewired Shelly EM - two channel energy meter so it logs power consumption for DHW under first channel and space heating under second.
3 way valve signal is used with relay switching the meter clamp for corresponding channel so I have the consumption in two separate graphs.

We still don’t have cold enough here to use floor heating fully.
I am courious how the regulation of room temperature will work. While using Glyn’s settings (constant flow temp 33-34C and Samsung controler as room thermostat) i am wondering if it will not overheat the space as there is around two hour delay between warm water entering the floor and feeling it in the air.

Maybe i will need some thermostat based on outside temp? e.g. when there is under 10C outside and under 21C inside at 15:00 let the pump run for 1hour, when under 5C/21C run for 2hours and so on… I dont know if something like that exists. Lets hope it will work as is with Samsung wired controller :slight_smile:

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Yes, it’s possible via modbus if you have the controller set on LWT mode rather than indoor temperature

Glyn, your DHW heating also runs with max flow temperature? I have the tank temp set to only 45C but the heat pump is putting almost 60C there at the end.

When I check Samsung weekly Energy Usage it shows consumption 12kWh and generation 29kWh. Does it mean COP (29+12)/12 = 3.4?
Is it OK for DHW?

No, I don’t have a max flow temp set. The flow temp during DHW will raise until the tank sensor measures the designed temperature plus overshoot. The smaller the coil in tank the higher the flow temp will need to be to achieve a given tank temperature. Maybe check the position of your tank sensor? And the overshot FSV?

I have my DHW set to 40C (45C on Eco), this results in a max flow temperature of 50C.

Do you know the size of the coil in your tank, and how long is the pipe run?

My DHW tank is not optimized for heat pump, it has only 0.7m2 coil exchanger, rated 9kW. The temp sensor is near the top so when it shows 37C it gets cold quickly…

Is there any way to tell this Samsung pump to not rush that much during DHW?

Which FSV do you call overshot?

Is my calculation correct?
“Samsung weekly Energy Usage shows consumption 12kWh and generation 29kWh. Does it mean COP (29+12)/12 = 3.4? Is it OK for DHW?”

That’s probably why your flow temp needs to go higher. No, not that I’m aware of.

Hi Lukas, I’m new to community so only just seen your post. I have an 8kW Samsung Mono Quiet so not identical but similar.

  1. As Glyn observed, there is no ASHP flow temp constraint for DHW (unlike the WL settings for CH). So the ASHP winds itself up to a high temp (with consequent high power requirement) until the hot tank temp setpoint is reached. I’ve moaned to Samsung about this to no avail (“no consumer demand for adding such an FSV”). This may be because most folk have DHW on 24/7 and the few minute’s top up takes hardly any power.
  2. Samsung advise at least 2m2 coil area (pref 3m2) for 8kW unit to limit this temp wind-up, so your 0.7m2 explains the high power you see. I have 0.9m2 (I retained my old tank) but as I only enable DHW 2 days per week I can’t justify a new tank/coil.
  3. I mitigate the high power during DHW demand by splitting scheduled heating time (2 x 15min bursts with 15min in between). This drops peak power demand by ~50% by giving the tank chance to convect some heat.
  4. You really need the tank temp sensor near the bottom, otherwise most of the tank will not be heated.
  5. Unless I misunderstand your numbers, your DHW CoP is simply 29/12 = 2.4 (not the 3.4 you posted). But happy to be re-educated…