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Viessmann gas valve

Harman009
Harman009 Member Posts: 10
in Gas Heating
Had a viessmann b1ha lockout with an F4 fault indicating a lack of flame detected. 

Got it back in action by adjusting the gas valve screw near the screen that says out with plus minus signs. Turning it higher brought the boiler back to life but now it's overfiring. Achieving 40c in low fire when it typically used to do 32. 

Money is tight and gas valves are 500+ without labor and I don't have the proper tools to diagnose the issue properly. I did the basic steps from the viessmann videos but couldn't find the problem. 

I am thinking a weak igniter or a problem with the gas valve. While I save up do you think its okay to leave it running how it is? Not in the heating season so currently it's just responsible for DHW via an indirect. 

This will cause short cycling right? Also what does this screw do? Is there an startup ofset I can change instead? 

I just want to make it last until my paycheck hits times are though. Although I rather have cold water than a blown up house


Comments

  • mattmia2
    mattmia2 Member Posts: 11,328
    Since you adjusted the mixture screw now you need a combustion analyzer or someone that has one.
    HVACNUTGGross
  • HVACNUT
    HVACNUT Member Posts: 6,504
    edited October 2023
    The throttle screw is only touched while doing a combustion test to adjust CO2 and 02 if needed. For all you know the boiler will soot now. You need a competent tech. Preferably someone familiar with Viessmann. 
    The only thing DIY for that boiler is maybe cleaning the igniter and flame sensor, and checking the drain and neutralizer. 
  • GGross
    GGross Member Posts: 1,397
    edited October 2023
    f4 is the lack of maintenance error code. You almost certainly have nothing wrong with the gas valve other than messing with that screw. You need a combustion analyzer to dial it back in correctly. But even before that a tech needs to check the incoming gas pressure, open the burner, clean up the whole heat exchanger, clean and inspect the condensate trap, and check out the igniter. Most of the time F4 is caused by a fouled up heat exchanger not allowing condensate to drain freely from the boiler. On rare occasions I have seen a bad ignition transformer, which requires a new board unfortunately as it is built in, on these instances it always came up as a repeated but intermittent fault. Viessmann has a 5 year parts warranty from the date of installation
  • Harman009
    Harman009 Member Posts: 10
    Okay thank you, I'll have a maintenance scheduled asap

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