Honeywell Gas burner safety control box MMI811.1 mod.35 0621120

The Honeywell MMI811.1 mod.35 is a gas burner safety control box designed for two-stage forced draught and combi oil/gas burners. It operates on a supply voltage of 220–240 V and consumes 10 W. The control box features a waiting time of 9 s, a pre-purge time of 24 s, a pre-ignition time of 3 s, and a safety time of 5 s. It supports flame detection via an ionization probe or an infrared flicker detector (model IRD 1020). The device is housed in a non-flammable plastic casing with IP44 protection and weighs 0.35 kg net.

Parts of this type are selected by matching the supply voltage, flame detector type, and timing parameters to the burner's requirements. The control box must be compatible with the burner's stage configuration and the specific flame detector used. Installation involves mounting the control box in any attitude and connecting the wiring base according to the burner's electrical diagram. Ensure the air proving switch reaction time and time delay settings align with the system's specifications.

Common failures include the control box not starting or locking out due to flame detection issues, such as a faulty ionization probe or infrared detector. Symptoms may include the burner failing to ignite, repeated safety lockouts, or the control box not advancing through its program sequence. Check the flame detector current, wiring connections, and the control box's internal cam mechanism for wear or damage.