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Viessmann EE FAULT

Tonerlow Member Posts: 85
We have a 200000btu Vitodens 200w providing slab heat to a 6500 ft2 shop at work. Getting a repeated fault of EE combustion lockout. Looking here for first things to investigate ? 


  • GGross
    GGross Member Posts: 1,105
    edited January 2023
    EE, is a no flame signal error, if you get these intermittently you may also see EB which is no flame signal during calibration.

    Flame sensor and igniter are possible culprits, depending on the age of the equipment you may be due to change them anyway

    Check that the condensate drains freely, burner chamber is clean etc

    confirm what type of fuel you are using, if LP confirm you have fuel..
    Check gas pressure incoming to the boiler at gas valve. Static gas pressure should be within operating range for your fuel type, listed on the side of the boiler (check that you are looking at the correct fuel type)

    Record gas pressures.
    -Static pressure before ignition
    -Pressure drop at ignition
    -high lockup pressure after burner shuts down

    repeat the gas pressure testing with a full load, meaning everything that uses gas attached to the same regulator on at the same time

    measure and record your gas piping size and total length from the boiler to the regulator.

    If you do not know how to correctly check the gas pressure, then you should call a service tech in.
  • Paul Pollets
    Paul Pollets Member Posts: 3,658
    Is there a Low Loss Header on the piping?
  • Tonerlow
    Tonerlow Member Posts: 85
    Yes low loss header. That feeds 2 manifolds for the slab (2 Zones/2 thermostats)