Honeywell Gas control unit MMG810.1 mod.43 0642520

The Honeywell MMG810.1 mod.43 is a gas control unit designed for forced draft and combined gas and oil burners of any nominal size. It operates with a supply voltage of 220–240 V and has a power consumption of 10 W. The unit features a waiting time of 9 s, a pre-purge time of 40 s, a pre-ignition time of 3 s, and a safety time of 3 s. It includes an air proving switch with a reaction time of 6.0 s and a time delay of 10 s between terminals 6 and C. The control unit has an amplifier sensitivity of 1 µA and requires a minimum current of 5 µA from a UV tube or ionisation probe. It weighs 0.35 kg net and has a protection class of IP44.

When selecting a replacement control box for a burner, ensure the supply voltage, timing sequences, and safety times match the burner's specifications. The control box must be compatible with the flame detector type (ionisation probe, UV sensor, or infrared flicker detector) and the wiring configuration. Check the mounting dimensions and protection class to fit the existing enclosure. Verify the power consumption and current requirements align with the burner's electrical system.

Common failures in gas control units include failure to start, intermittent operation, or lockout due to flame detection issues. Symptoms may include the burner not igniting, shutting down after a short period, or displaying an error code. Check the flame detector, wiring connections, and supply voltage for faults. Also inspect the air proving switch and ensure proper airflow before the unit initiates the pre-purge cycle.