Do you have the DHW on timed periods or on continuous within x degrees of set temp?

Does the DHW ever reach the 50C set temperature?

Eddi won't be messing things up.

Hi.  Thanks for your reply.

I don't think I have the DHW on timed, but I wouldn't know how to do that, or to check it.

The DHW certainly does sometimes reach the temp.  See attached pic.   After last night's Cold Bath farrago I blindly increased the temp to 52c; turned the Mode to Forced; and flipped the eddi to Boost.  I'm sure the eddi does something as when it blew up in the autumn I had no hot water at all until it was replaced under warranty.  As a result the temp got up to 61.8C and I think has been coming down since.

The eddi will be activating the immersion heater in the tank.

Posted by: @gary

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The eddi will be activating the immersion heater in the tank.

Sorry for a very basic question, but how does that differ from what the heat pump is doing?  Is the heat pump not also powering the immersion heater in the tank?

When the eddi packed up completely for a week last autumn, we had no hot water for a week.

@ntruby sorry I haven't read your entire thread, but your heat pump should be heating your hot water through a separate coil in the hot water cylinder by transferring heat from the heat pump primary flow to the water in the tank this is a completely separate and different process.

All the eddi can do is divert excess electricity usually from solar to an immersion heater to electrically heat the hot water this is not the same as what the heat pump is doing.

If you had no hot water when the eddi packed up then your heat pump isn't setup to heat the hot water in your tank or it is only activating the immersion through the eddi and not using the heat pump directly

@gary Thank you, Gary.

Is there any way from the Samsung controls that I can verify how the heat pump is heating the hot water?

@ntruby There will be but will need someone who knows the Samsung controller im sure someone will be along to explain shortly

@ntruby  What @gary says is correct, the eddi only controls the immerser to dispose of excess solar energy. The heatpump has the facility to control an immerser too but this should only really be required for the weekly legionella pasteurisation.

I am concerned that you say you have no hot water without the immerser, that's not too handy. I once had this problem and it went undetected for three months due to a howling balls up mostly on my part unfortunately.

To see whether you have any timings set up, do the following on the controller:

From the front screen press the gear button and navigate to schedule and press ok.

If there's any timers set you will see them here, if there's none you can add some.

To add a schedule highlight add schedule, press ok, daily schedule, press ok, set type to DHW (not quiet), set on or off and set time.

Allow maybe 1.5 - 2 hrs per on - off period to allow the cylinder to heat up.

If you happen to be on Cosy Octopus you can set the timer to use the cheap tariff, 

If you get all this set up, when the DHW comes on you would expect to hear the zone valve or three way valve moving and the circulating pump or pumps come on. You can also check the status from the front screen by doing the following:

Press the gear button and navigate to operation status.

You would expect to see compressor highlighted in blue to show it's operating and also the water pump in blue. The booster heater should be greyed out as it shouldn't be on.

If you are unsure of the bits and bobs around your heat pump / water cylinder etc you can upload some pics and I can hopefully point you in the right direction.

@derekdeleon Hi Derek and thanks for your reply.

I checked the system as advised: no schedules are set.

At bath time this evening the system was showing Set Temp: 52C ; Actual Temp: 49C

I turned off the eddi and ran a bath.

When the bath was full the temp was 29.4C

It has since risen and is now at 53.1C.  So far as I can tell from my Myenergi and SolarEdge, all this was achieved via battery discharge.   (I don't know if the fact that the power came from the battery and not the grid).

 So all good I think.  But I still don't understand why, sometimes, the temp is say 42C and nothing seems to be happening to put that right, and what I can do to fix it.

Your setup is will be constantly maintaining the temperature at your desired set temp of 52deg as there is no timer set up.

There is hysteresis in the system which is adjustable (field setting 3023). Hysteresis is the difference between the DHW start and stop temperatures, as standard it is 5deg so it heats the water until 52deg but won't come on to reheat again until the temp goes down to 47deg.

It is worth remembering that the temperature sensor probably sits halfway down the tank so even when it reads a few degrees lower than you expect, there will be hotter water above the sensor since water stratifies, that is to say it sits in layers with the hottest at the top.

I still recommend you observe the operation status page the next time the DHW is heating just to make sure it is using the heatpump compressor to do the heating, otherwise you would be wasting a lot of energy.

Posted by: @derekdeleon

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Your setup is will be constantly maintaining the temperature at your desired set temp of 52deg....  it heats the water until 52deg but won't come on to reheat again until the temp goes down to 47deg.

This doesn't explain, though, why the temp was down to 44C at bath time yesterday - and the bath was genuinely too cold to stay in.   Also, I don't know what made it go up to 61C subsequently as, unforgivably, I changed two things at once: putting the eddi onto Boost, and setting the Samsung mode to Forced.

Posted by: @derekdeleon

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I still recommend you observe the operation status page the next time the DHW is heating just to make sure it is using the heatpump compressor to do the heating, otherwise you would be wasting a lot of energy.

I'm sorry: could you spell out for me how to check this please (or point me to a link).

Thanks!

N