Thanks Ivailo, yes Arotherm 125/6, R290-Propane unit.
@Andre_K@all, may I ask, do you see EEV outlettemperatures above airintake temperatures? My thinking is that an eev outlet temperature is the boiling temperature in the evaporator. But if that temperature is higher than airintake, it can’t pick up any heat… Or are you maybe not looking at these temperatures? I like to understand whether I am the only one with this strange reading.
Btw, I don’t have proper energy/ COP readings yet. Working simultaneously on GitHub to get more message definitions in the tables. There appear still quite a few messages on the ebus that do not get translated since they are not in the definition files.
I was actually logging everything coming out of ebus, so here you are. It looks like RunDataEEVOutletTemperature closely follows another temperature value from ebus, EEVOutletTemperature, the difference might just be timing&rounding. It drops below the air inlet temperature for me, which is also consistent with my outdoor temperature sensor. The attached image shows an active cycle between 12:15 and 12:45.
Not sure if this is the right thread or if this has been asked elsewhere.
Has anyone had an issue with the vaillant tank temperature sensor?
I made use of the cheap electricity overnight to run an anti legionella cycle to increase the temp of the water in the tank (1 in image below). I know the cycle ran properly from the monitoring, eg got up to about 75 degree flow temperature. I used a bit of hot water for one shower this morning but not much. When I have done this in the past there has been plenty of hot left in the tank to not run my normal hot water cycle (48 degree setpoint).
However I noticed my usual scheduled 1300 hot water started running so I checked the cylinder temp sensor on the controller and it says 25 degrees. It then ran until the temp sensor read 49 degrees (2 in image below).
Eg even though [I am pretty certain] there was plenty of hot water in the tank, the sensor read a temperature below setpoint so ran .the standard hot water schedule. Is there a way to check the tank temperature sensor is working or reset it somehow?
Or could it be something else? eg maybe the 3PV didn’t close during the legionella cycle (seems unlikely) or there’s a leak somewhere that pissed all the hot water away (again, feels unlikely).
Do you know where the temperature sensor is positioned within the tank? It’s commonly installed at the bottom so will read low after a shower as the cold water rushes in to replace the hot water as it’s drawn out, even though there’s still plenty of hot water at the top.
Setting the trigger point lower will help prevent premature heating.
Are you able to plot the tank temperature over time?
The temp sensor is ~1/3 of the way up from the bottom of the cylinder - [10] in image below, approx equidistant between heating inlet [7] and return [1] and fairly close to the cold water inlet [4]. Perhaps the water hadn’t stratified between taking shower and start of normal hot water cycle. Although I think there was at least 3 hours between shower and scheduled hot water time which to me feels intuitively enough time for the cold water to drop to the bottom of the tank (maybe not though).
I turned your idea to reset the energy integral into an automation in Home Assistant - here it is if anyone else wants to use it. It currently needs both the MyVaillant integration and ebus as I have not yet found how to turn off the heat pump using ebus. I turn the heating back on twice just to make sure - in case the API is wonky. Local control would definitely be better.
Avoid Noise reduction mode when it’s cold outside!!
I’d been playing with Noise Reduction mode the other week and forgot to turn it back off.
So after coming out of the hot water run at 3am (to 1pm, purple highlight) the heat pump wanted to go full beans on the compressor at times (upto 110 rps), but NR mode capped that at around 60-80 rps.
See ebus trace of the compressor speed from home assistant.
Capping the compressor meant the heat pump couldn’t achieve target flow. ie, couldn’t reach the grey line. So the internal temp wouldn’t rise as fast as it should.
Also noticeable was that as well as defrosts being more frequent. The were also less useful. I watched the back of the unit during and after a defrost and many of the fins didn’t clear. Like the compressor limit also transferred to defrost?
So I ended up in some sort of defrost doom cycle where it never fully recovered from defrost to defrost
You can see at 2pm (green highlight) after the afternoon hot water run where I disabled all noise reduction schedules, the heat pump got right back to normal service, got back to target temps and the internal temp started to rise again.
And the defrosts did their job by clearing all the fins. The defrosts then became less frequent.
Thanks for this, it could explain my heatpump’s behaviour. I do have NR on and Saturday’s performance was much like yours. Morning was frequent defrosts with never reach target flow temp. By afternoon it had sorted itself out. I thought it was just the outside temp recovering a few degrees, but maybe not.
I’ll turn NR off and see how it goes over the next few days.
Tnx for info, i started using NR mode to test it during warm days, it went form -2 to +13 in 1 day so I wanted to see how it will work, but next week temperatures outside will go below 0 again. We have a lot fog days with 0 C and a lot defrosts
My 7kW Arotherm Plus is having what I believe to be defrost-related issues…
During the last couple of cold spells, with overnight temperatures of -2C - 0C, the DHW cycle has failed to reach the 50C set tank temperature.
The cycle is scheduled to run once a day at 1am (cheap period), with a 4-hour allocated window. 250L Vaillant tank.
The worst was this Sunday just gone, where the legionella cycle took the full 4 hours, consumed ~5kWh, and only managed to reach just over 50C indicated tank temp (usual disinfection cycle achieves ~66-70C).
The result was a lack of usable hot water, with us barely getting a single shower out of the 250L tank when it’s been cold outside.
How should an Arotherm Plus manage defrost during a DHW run? Does it use the DHW tank as a source of heat, or does it flip the 3-way valve, use the space heating water, then flip back to heating DHW? I did look at the evaporator during a couple of the failed DHW runs, and noticed it was a solid lump of ice…
Is there anything I can do to mitigate this? I’m not using any kind of noise-reduction mode or compressor limit, DHW offset is at 5K. Everything works perfectly at warmer outdoor temperatures.
Ah sorry, my bad - it switches to space heating for defrosts. Eco mode might have been the reason - even my 10 kW unit needs 2 hours for a legionella cycle at low outdoor temperatures in eco mode. You can also try to pick balanced mode, as this will run in full power at the beginning to bring the flow temperature up, then run in eco until about 50°C flow temp and then switch to normal again.
I believe the Arotherm Plus have surport to automatically use a electric emmerson for DWH when the outside temperature is below a set value. Shame it will not automatically delay the legionella cycle by a week or two when it is very cold outside.
