Well I’m at a bit of a loss..I’ve never seen this behaviour nor observed if from other Nibe systems.
just for curiosity, what’s the value of 1.30.3 menu?
Also can you get your S1 temperature to change at all? What happens if you choose a different curve, maybe 8 or 9? Does S1 adjust itself? I’m trying to understand better if your WC is having any effect on the S1 at all..
So, my “haunted Nibe” has Menu 1.30.3 ( External Adjustment ) :
Unfortunately S1 is a calculated target. There is no menu where you can set anything about S1. I assume that this S1 changes based on several parameters collected from the sensors. On another note, I was wondering if there are parameters that can be changed in the Manual Operation Menu?! Has anyone had any experience with Manual Mode?
Correct. S1 starts out as a direct read-off from the WC Curve, based on the Outdoor Temperature, then it can get adjusted up or down (a little) based on how the Indoor Temperature compares with its Set-Point (if control based on Indoor Temperature is selected). With the older controller models (e.g. SMO 20, which is what I have) I don’t believe there are any other sensors which influence S1, but the SMO S40 is supposed to be more ‘advanced’ so might be different.
The high, unchanging value for S1 seems to be the key issue. That’s what the NIBE technicians need to be explaining / correcting.
It really is very odd. I would have expected the Factory Reset you mentioned in your first post to have removed any ‘bad’ configuration settings that might have been present - and the sensor inputs all look to be sensible. Maybe the firmware has become corrupted and needs reloading?
“The high and unchanged value for S1 seems to be the key problem. This is what the NIBE technicians need to explain/correct.” Yes, I sensed this too. It’s just that the Nibe technician/installer told me that he didn’t know what to do in this case and that first of all I should buy a voltage stabilizer for the pump to eliminate the possibility of the mains current disrupting the proper functioning of the System. The pump has been installed since December 2023 and nothing in its behavior gave me any indication that any voltage problems had affected its functioning. I’m a bit confused by his request. Do you have an opinion on this? Regarding the Firmware, the problems started after the update I performed on January 7th, in the evening. The technician came a few days later. I deduced that the new firmware might have been corrupted so I reinstalled the previous firmware and it seemed that this was the problem. But, after a short period of time DM started to drop and stabilize at -7oo --800 (there were even -1000). Since then, a few more updates have come that I installed but they had no influence on the functioning.
It looks from here the external sensor is influencing it as it is checked, I doubt it will help but maybe try disable and report back if S1 changes
You could also try adjusting your curve to a new value or some offsets or setting your own curve up. This might kick something into life
Also can you confirm if S1 remained at 45 degrees when you did a reset of the DMs to zero.
I don’t really follow the Nibe technician voltage theory at the heat pump, this seems a software logic type problem at the controller.
After resetting the DM, S1 remained targeted at 45. I followed your recommendation and disabled the external sensor influence and set my own curve. A few days ago I disabled the BT50 influence in menu 1.3.3, but today I noticed that menu 1.3.4 (Zones) has the setting "Climate systemClimate system 1
Affect the heating of the climate system : Yes and the disable button is locked on ON (on the SMO S40 screen). I’m waiting to see what happens… As for the “technician’s theory” I think he wanted to “keep me busy” to have time to think or time for other work he has. For now I won’t buy a voltage stabilizer, I’ll install a relay that monitors the current parameters.
Gentlemen, hello again.
I would like to bring an update to the problem that gave me a headache. The problem was generated by the integration between Nibe and the Fronius inverter via the Modbus protocol. I still don’t fully understand what happened but I assume that those settings (undocumented by Nibe - or I couldn’t find any documentation) would only work correctly if the Modbus Register sent by Fronius is exactly what Nibe expects.
Probably, Nibe can interpret the values as temperature sensors or setpoint commands (Setpoint 45 degrees that worked for me, although I didn’t set anything like that). Now, I’m just happy that the system has returned to normal behavior and decent energy consumption.
Thank you to those who had the patience to listen and ask questions.
Thank you for the update! No wonder we were all stuck with that one.
So your solar inverter was telling the Nibe controller to set at 45 degrees via the modbus..?
Out of interest how did you find this out / diagnose it? Did Nibe help you or was it trial and error to find out?
The problem started in Dec. 2025 when I found out from the website of the local company authorized by Nibe that through the Modbus protocol you can set up a collaboration between Nibe and Fronius. The idea of testing this connection was that during the winter period I would set a time interval in which the production of the panels would (super)heat the water in the water tank to be used in the installation later. This is the concept that seemed interesting to me at the time. I made the Modbus connection, the devices were seen on the network, settings appeared in the dedicated menus of Nibe 4.2 Plus functions
4.2.2 Solar electricity
4.2.5 Smart Price Adaption
After a few days I realized that these settings need to be investigated more deeply to understand how they work, so I disabled all the settings in 4.2.5 Smart Price Adaption (in this menu the period of the day and the lowest tariff of the day were defined) but I left Modbus active and the monitoring of the current produced by Fronius through his SmartMeter. Now, I can only deduce that the deactivation of the settings although the sliders were clearly set to the deactivated position, the physical deactivation did not take place! Anyway, it remains in my analysis and that of the Nibe representative. It is a strangeness that persisted for approx. 4 months during which the Nibe representative performed 2 factory resets of the system. I’m still trying to “digest” what happened and for now I only have assumptions in my head. In time I hope to clarify them together with the man from Nibe.
