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Solution for consistent E8 Fault code on Viessmann Vitodens 222-F LP Boiler?

BobbyC10 Member Posts: 2
In Nov 2013 I had a Viessmann certified rep install the new Vitodens 222-F boiler to for my new LP baseboard heating system. Since that time I periodically receive the Fault Code E8 - Combustion Control Error. After running many tests and checks there are no trends that consistently cause this fault code. The boiler worked during extremely cold temps, stress test, small fluctuations in temperature change, and other diagnostic checks. The only recommended solution was to re-align the combustion component inside the boiler so condensation does not drip onto the ionization rod.

This did not fully solve the problem as I continue to get Fault Code Error E8 frequently. What else might be causing this? Is it a gas pressure problem, a dirty ionization rod, or something else?

Please note, I have used 2 separate LP Gas providers during this time.

Thanks in advance for any information or assistance one can provide on this problem.


  • RobG
    RobG Member Posts: 1,850
    Combustion Analysis

    Was a combustion analysis done on the unit?
  • Robert O'Brien
    Robert O'Brien Member Posts: 3,450

    Is microamps out of range. Combustion analysis and gas pressures are required to go any further. I am assuming it was set to LP operation?
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  • JharrisSeattle
    JharrisSeattle Member Posts: 26

    Is the system outfitted with a condensate neutralizer that may be reducing the rate at which the condensate can drain from the exchanger . (Plugged up,etc) I ran into a issue on a b2ha vitodens where the condensate was backing up into the combustion chamber and caused a EB combustion controller lockout. Condensate found its way in between the refractory and burner plate. I had to remove the burner and refractory to completely dry them out per Viessmann. After doing so and fixing the condensate draining issue, there has been no more problems with the unit that I know of.

    Just a thought...

    Good luck!
  • CMadatMe
    CMadatMe Member Posts: 3,086

    Is caused because the ionization current is outside the range. Generally gas pressure issue. I have come across a bad wiring harness between the the gas valve and control. Also make sure the gaps are correct on the ionization and ignition electrodes.
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."