Buderus boiler ignores set temperature and setbcack mode

Atmonaut

Hello all,

I am a new member here and while I have been reading topics for the last couple of weeks trying to figure out my issue, I have not managed to do so. Hence I am creating my own topic trying to see if anyone can help or has experienced something similar.

Summary of my setup:

• Buderus Logamax Plus GB162-15
• RC35 thermostat installed in the living room
• EMS-ESP installed in the service port for monitoring/remote access (and integration with Home assistant)
• One unmixed Heating Circuit with radiators
• Domestic hot water (3way valve charging)

Description of the problem:

Even if I set the heating operating mode in "night mode" (shut-down setback mode selected in settings) the burner keeps on firing every 10 minutes. If I have any radiator valve in the living room then the temperature keeps on rising way above the setpoint even for day mode. if I close all radiators manually then the boiler keeps on running every 10 minutes only briefly to raise a bit the flow temp. It seems night/day mode is ignored, and even if I have the rotating dial on the boiler set to "Aut", the boiler tries to always bring the temperature to 90C.

This is how the system behaves when all radiators are shut:

This is how it looks with the living room radiators open:

I attach a few screenshots of the settings on the boiler and the thermostat.

Thermostat Settings and Sensors 4.png

Thermostat Settings and Sensors 3.png

Thermostat Settings and Sensors 2.png

Thermostat Settings and Sensors 1.png

Boiler Settings and Sensors 4.png

Boiler Settings and Sensors 3.png

Boiler Settings and Sensors 2.png

Boiler Settings and Sensors 1.png

Any help or input will be greatly appreciated!

DownieC

Our Buderus boiler does this when it’s in manual/ override mode. There’s a rocker switch on the front of the Logamatic (it has a hand on it for manual) that needs to be on automatic to switch out of the manual/override mode. It’s confusing because the boiler can be in manual/ override mode even if “automatic” is displayed on the screen. We don’t have the same model as you but maybe you are in manual/ override mode?

Atmonaut

Hello,

Thanks a lot for taking the time to comment! I have a feeling that indeed something like this is happening for some reason. However the manual mode on GB162-15 is currently not enabled. I attach here the manual section for the manual mode that I have been referencing when making sure it is off. Maybe there is another override option somewhere else thought that I am missing.

Any other proposal will be greatly appreciated!

Grallert

Hmm, Maybe you've covered this. Are both knobs turned to AUT? This allows the room sensor to communicate with the boiler control. Maybe you've done this but that's where my thinking goes.

Atmonaut

Indeed I had everything to AUT but hasd to change it to a fixed temp because with the setting to AUT I had the same problem still but even worse, as the temp of the boiler constantly modulated around 90C. At least when I set it to 70C it modulates around that temp and the heat losses are smaller and so is the wasted energy. I am really confused as to which component forces the boiler to constantly maintain the flow temp even in shut_down mode!

Thanks again for your time!

Grallert

Ugh. It seems like the boiler control and the Room control aren't getting the same information. Like one doesn't know the actual temp of either the water or the room. Are there two pumps on your system? A system pump and an internal boiler pump? I'm just thinking out loud here. If there were a boiler temperature sensor failure or any sensor failure for that matter there would be a fault code. So the bc thinks it's doing the right thing, it seems, it's doing what the rc is asking it to do. I'll be following along here. Sorry I don't have any solid input.