<![CDATA[iFixit - Answers With Device "Viessmann Boiler"]]> https://www.ifixit.com/Answers/Device/Viessmann_Boiler?rss=yes en-US Fri, 03 Apr 2026 18:48:59 -0700 <![CDATA[Viessmann Duomatik: Procedure to set up the control unit after replacing the battery]]> I have a faulty Viessmann Duomatic. It appears that the battery inside the control unit is dead. I have just had a heating engineer come and, after consulting with Viessmann over the phone, got my boiler working again by pressing a few buttons on the control unit. He told me the battery was 'tired' and warned me not to turn the power off until I had replaced the control unit (£450). I can easily change the battery but what buttons do I need to press to re-initialise the control unit or will it just work once the 3.6v battery has been replaced?

Update (07/05/24)

The control unit was basically not displaying any of the values for the three thermistors connected to it, it is as if it wasn't looking at the sensors and the codes that were entered by the heating engineer initialised the controller to look at the sensors and display the values on the display. Without a valid temperature for the boiler it wouldn't do jack. Is there not a Viessmann engineer out there with access to the engineering manual that could look up the initialisation procedure for me?

⟐ Commented July 06, 2024 at 10:02 MST

]]> https://www.ifixit.com/Answers/View/856962/Procedure+to+set+up+the+control+unit+after+replacing+the+battery https://www.ifixit.com/Answers/View/856962 Sat, 06 Jul 2024 10:02:46 -0700