Samsung EHS mono 5kw settings

Tony you don’t say which Samsung you have, but if it has the MIM-E03EN controller you may find the following useful (sorry if you already knew some/all of this):

  1. The controller gives you the option to define two separate water laws (WL) - one for radiators and one for UFH. These are called WL1 (via #2021/2) and WL2 (via #2031/2). You define which of these WL to use for LWT control with #2041. (The manual shows WL1 in use for UFH as default, but there’s nothing to stop you using WL1 for radiators as long as all the FSVs are used consistently.)
  2. If you use the roomstat built in to the MIM, you define how the outdoor unit and circulation pump operates using #2093, and #2091/2 should be set to “Not use”. If you have a 3rd party remote roomstat, this is done with #2091 (if WL1 is in use) or #2092 (if WL2 is in use), and the #2093 setting is irrelevant.
  3. Each of #2091/2/3 offer options to 1) start/stop the outdoor unit just on the roomstat on/off signal, or 2) start/stop the outdoor unit either from roomstat on/off signal or WL off signal (whichever occurs first). The latter has three sub-options which define how the circulating pump should operate (basically, off/on/cycling when the outdoor unit stops). The WL on signal occurs when LWT falls to ~2degC below WL setting (but not less than 5mins after the off signal).
  4. The MIM roomstat is in the remote display, so obviously if this is located somewhere subject to rapid temperature changes, or with a small thermal inertia, it will stop/start the outdoor unit more frequently. Most owners either locate the MIM remote display somewhere where these effects are less (e.g. the main living room, as Lukas has done), or install a third party remote roomstat (also likely the living room, as I have done).
  5. There are pros and cons of using WL in addition to roomstat control. The main pro is that LWT cannot exceed WL setting, so avoiding high LWT and consequent lower CoP. The main con is that outdoor unit cycling is likely to be more frequent, because the thermal inertia of the circulating fluid is likely to be much lower (hence temperature changes higher) than that of a large room.
  6. The User Manual appears to be slightly out of date, as its description of some FSVs - particularly #2091/2/3 - is not consistent with what you see on the MIM remote display. (I think the translation from Korean may be a factor too.)

Hope this doesn’t confuse things even more…


Hi Alex, I asked Samsung technical support about EHS Cloud and apparently the service is not yet ready. It does sounds like it could be useful in the future.

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Hi, thanks for that, I’m slowly getting used to all the abbreviations! The installers did not give any real explanation of its use, and it is only in the last day or two I have understood enough to realise that they fitted an external thermostat, I didn’t understand why the thermostat told me one temperature and the remote controller said another one, and when I looked at the PCB why there was no connection between the recorder of the thermostat and the thermister socket in the board. I am assuming WL uses the temperature down on the display when doing it’s calculations.
The installer did make some silly errors, seeing things as if I have ufh and not radiators, so I have done what I can right now. I think I’ll wait a week or two, then start playing again!
Thanks, your explanation has helped

Not quite, Tony (if I understand your wording):

Water Law (i.e. the target LWT) is purely based on ambient temperature, and not the temperature you see on the remote display, which is simply the air temp wherever the latter is located.

Unfortunately, the remote display does not show ambient (= outside) temperature. But if you set up #2011/2 and #2021/2 (if you use WL1) or #2031/2 (for WL2) correctly, and you measure ambient temperature yourself, you will see that the controller varies LWT correctly with varying ambient temp. (It does this by varying the compressor speed, but that’s another whole subject in itself…)

[Note - the manual uses the term “water out temperature” instead of the more widely accepted “LWT” (Leaving Water Temperature) for that of the fluid leaving the outdoor unit.]


Thanks, that explains much more clearly than the book, and shows I have a lot to learn.

Hi Glyn, when I select indoor on MWR-WW10N, Im getting error E121. Power on and off dont solve it. Do you know what can be the reason?

Hello Michal.
The manual says “short- or open-circuit error of the room temperature sensor of the Zone 1 indoor unit” (i.e. a faulty roomstat). Might this make sense?

Hi Sarah,
Yes, I have seen that in manual, but I thought sensor is internal in the panel? Glen YT video was suggesting that and my gas heater panel is like that. Maybe some more settings have to be change before #2091 and #2092 before enabling indoor sensor.

As I understand things :upside_down_face: there is a roomstat in the controller remote display, and if your installer located this somewhere useful like your living room, then you would set FSV 2091/2 to 0, and programme your room temp on the remote display. If the display is elsewhere (mine was put in my utility room - OK for access, but no good for living room temperature control - then a remote roomstat is required, with 2091 (if WL1 is used) or 2092 (if WL2 is used) set to “Use” with one of the codes for using weather comp or not.
There are potential problems with using a TPI wireless remote roomstat (see above and other threads) but otherwise the remote roomstat setup works fine (unless it is faulty of course…)

The installer is me :wink: and this is not my daily job but I’m electrical engineer and just came to same conclusion as you, panel is placed in my dinner next to gas heater panel. I’m just playing with setting as I use it for DHW now and it will be few months before I switch it on for floor heating. FSV 2091 and 2092 have separate input for thermostat in heat pump, so can`t be related to panel thermostat I tested it anyway and alarm came again when switched control mode.

Mmm I’ve not seen that before, that sounds like a possible faulty LCD touch controller. The sensor should be inside the controller, unless you’ve connected an external sensor. Could you share a photo of your main control board?

Hi Glyn,
Looks like temperature sensor is connected.

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That’s cool. Can you measure the resistance across it? It should change with temperature.

Could you share a photo of your main controller board? Do you have any additional temp sensors connected to it? You should just have a DHW tank sensor.

I measured 11,3kOhm with 23deg C. I think this is correct for NTC sensor with this temp. I have only DHW tank sensor (blue wire) with works fine.

How is your LCD touch controller connected to your main PCB? I see the F3/F4 connections are not connnected. This is what the wiring diagram for my Gen6 looks like, the touch controller is connected to F3/F4:

Yes, you are correct the the controller is connected to F3/F4. Picture was taken before I completed connections and on the begining I connected it wrongly to F1/F2. The unit main pump is originally connected to B7/B8 and my excising pump (after buffer tank) is not PWM so I connected it together only as signal output to relay with is controlled by 3 port valve signal so it`s enabling signal only if DHW circuit is not running. This pump is controlled by gas boiler/heater and heat pump signal via integrator. I have also B4/B5 connected as gas heater start signal set up from -15 deg C.

Ah right, that makes sense.

What’s are these connectors? I don’t have anything connected here on my system, and the UK install manual does not even label this connector


There is front PCB and it looks like is connection CNS051 to terminal in front SG Ready and zone room temp. but I don’t have nothing connected to it.

Ah interesting, I don’t have a front PCB on my system. Is yours some sort of all-in-one integrated indoor unit?

If you’re not using it, you could try unplugging it? It may be interfering with you using the indoor touch controller as the main thermostat

Yes, It have everything inside: flow meter, pump, safety valve etc. I got in touch with local Samsung heat pumps installer (listed on Samsung website) to get my guarantee validate, I will check with him first.