Viessmann F1 fault code

[Plumbergasfitter]

Hello everyone. I have a Vitodens WB2B 105
Fault code F1.( Flue gas temperature has exceeded 230 deg F ) . Boiler water temperature reaches 115deg then the burner ramps up to high fire . The flue gas temperature goes up to 150 deg then faults out . Replaced the 12 yr old sensor no change , faults out on high fire. With the flue gas sensor removed the boiler will heat up to 170 deg with a flue temperature of 195 deg confirmed with my combustion analyzer. I would really appreciate any advise. Thanks
Ralph

 

[John Gayewski]

Have you tried descaling or cleaning the heat exchanger? It sounds like your not getting the flu gas to pass. With flue gas temp that high you probably aren't condensing. Have you checked the you don't have a blockage in the condensate?

 

[Sponsor]

 

[Fitter30]

Here's the service manual page 76 starts sensor resistance/ temp. Sounds like a leaving water temp sensor might go south at 115° but must in range at a lower temp not shorting or opening the circuit.

https://www.google.com/url?q=https://viessmanndirect.co.uk/files//b73296b2-033f-43aa-b255-a9d100f55bfb/WB2B%25204.8-35kW%2520Service.pdf&sa=U&ved=2ahUKEwjwvcKwxvmEAxWLtokEHf09CE4QFnoECAQQAg&usg=AOvVaw00fFeRGTWW9smdKIEC69G-

VIESSMANN VITODENS 200-W WB2B 80 START-UP/SERVICE INSTRUCTIONS Pdf Download

View and Download Viessmann Vitodens 200-W WB2B 80 start-up/service instructions online. Wall-mounted, natural gas-fired condensing boiler. Vitodens 200-W WB2B 80 boiler pdf manual download. Also for: Vitodens 200-w wb2b 105.

www.manualslib.com

 

[Plumbergasfitter]

Have you tried descaling or cleaning the heat exchanger? It sounds like you’re not getting the flu gas to pass. With flue gas temp that high you probably aren't condensing. Have you checked the you don't have a blockage in the condensate?

Thanks John. I have descaled with Fernox and going to clean the combustion side again . It hasn’t been cleaned for a few yrs. Seems like LPG creates more combustion residue than Natural Gas. Never came across a boiler that was this fouled up.

 

[Plumbergasfitter]

Here's the service manual page 76 starts sensor resistance/ temp. Sounds like a leaving water temp sensor might go south at 115° but must in range at a lower temp not shorting or opening the circuit.

https://www.google.com/url?q=https://viessmanndirect.co.uk/files//b73296b2-033f-43aa-b255-a9d100f55bfb/WB2B%25204.8-35kW%2520Service.pdf&sa=U&ved=2ahUKEwjwvcKwxvmEAxWLtokEHf09CE4QFnoECAQQAg&usg=AOvVaw00fFeRGTWW9smdKIEC69G-

VIESSMANN VITODENS 200-W WB2B 80 START-UP/SERVICE INSTRUCTIONS Pdf Download

View and Download Viessmann Vitodens 200-W WB2B 80 start-up/service instructions online. Wall-mounted, natural gas-fired condensing boiler. Vitodens 200-W WB2B 80 boiler pdf manual download. Also for: Vitodens 200-w wb2b 105.

www.manualslib.com

Thanks Fitter30
I’m going to replace all the sensors. It’s a 12 yr old boiler , running full time for Heating and DHW. I’m going to clean the HX combustion side again. Was going to use Axitherm Clean F9A until I found out how toxic it is. Looking at something safer