Climate Solutions Community

km1967 · ‎31.07.2026

Thanks for help, advice, and clear instructions. I was able to access to coding plug, see attachment, and cleaned both sides' contacts with a bit of alcohol On power up I saw a progress bar, which was not there on other power ups. But after that disappeared shortly thereafterwards I got same B7 error. After acknowledging the error, I tried "R" again and this time it cleared, so boiler is currently up again. What would you advise now? Would the part you suggest not be replaced by Viessmann under the boiler warranty? Would it not be wise to maybe get a replacement part now?

km1967 · ‎30.07.2026

hello This is related to an old thread, see: https://community.viessmann.de/t5/Gas/200-w-und-B7-und-pressure-druck/m-p/626377#M145748 The book given with boiler is marked Vitodens 200-W Typ B2HB / B2KB. The kessel number is 7570782... At time of that thread I was able to clear the issue with a power reset and pressing "R", though it took a few tries. Same issue came about a week later, that time just a single press of "R" fixed it. It has happened 3rd time today and even with power cycle I have not been able to complete the reset successfully The pressure issue on that other thread seems non-issue, gauge is where it was several weeks ago. One common factor to all 3 issues is that this has happened on very hot days (ca: 35 deg C) here in Bavaria. But the boiler is in my cellar, which is pretty cool in caparison. Boiler is ca: 6 years old.

km1967 · ‎11.07.2026

Yep, this is what I thought, just wanted to be sure. I am in Bavaria, so that that its a German market is of course correct. I'm OK with the German manuals, but English is my native language so thanks for the docs too. When I'd opened both valves and let pressure gauge increase to ca:, 1.5, it had dropped back to ca: 1.0 when I closed one valve again. It is now at around 1.2. it got closer to 2.0, but as soon as I closed one again it again drops by around 0.5 bar. Dunno if this is normal. Both valves back in the original position now obviously. I will see if this pressure holds over coming days, and if B7 comes back. Currently, and since around May, the boiler is only feeding the hot water tank, heating it around 3 hours per day. The central heating is (as is usual here) off for the summer. I am more used to the combi / on-demand boiler style which are more common in UK, and usually the filling loop valves are ... closer to the bloiler itself. Thanks a LOT for your help/advice.

km1967 · ‎10.07.2026

thanks for response and advice. Can you please send me link to the English language manuals, I have only the (paper) German ones dated 07/2019, which was about 3-4 months before the boilers were installed, and which were supplied by the vendor at that time. The book given with boiler is marked Vitodens 200-W Typ B2HB / B2KB. The kessel number is 7570782... (can send full number if you need it). I am not 100% sure how to fill/top up as I've never done this before. There is large water tank (COSMO speicher) and a COSMO MAG-H (we have underfloor heating if it matters, no radiators). Below are some fotos.

km1967 · ‎10.07.2026

Hello Englisch and Deutch DEU: My 6-year old Vitodens 200-W stopped with error code B7. I pressed R to reset, but same error returned. I then powered off, approx 15 minutes, and then on again. Same error again, but on pressing R this time the boiler came up and is now working. However, I notice the pressure is barely more than 0.5 bar. Sadly I dont know what it was in years before, and whether this relates to the B7 issue. What should I do now, if anything? ENG: Meine sechs Jahre alte Vitodens 200-W hat mit dem Fehlercode B7 den Betrieb eingestellt. Ich habe zunächst die R-Taste zum Zurücksetzen gedrückt, jedoch erschien derselbe Fehler erneut. Anschließend habe ich die Heizung für etwa 15 Minuten vollständig ausgeschaltet und danach wieder eingeschaltet. Zunächst wurde der Fehler erneut angezeigt, doch nachdem ich diesmal erneut die R-Taste gedrückt hatte, startete der Kessel wieder und funktioniert seitdem. Mir ist allerdings aufgefallen, dass der Anlagendruck nur knapp über 0,5 bar liegt. Leider weiß ich nicht mehr, wie hoch der Druck in den vergangenen Jahren normalerweise war und ob dies möglicherweise mit dem Fehler B7 zusammenhängt. Was sollte ich Ihrer Meinung nach jetzt tun? Muss ich etwas unternehmen? Vielen Dank im Voraus für Ihre Unterstützung.

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