Resideo automatic burner control approved for gas and oil operation, also for WLE. Not for new systems, only as a replacement! Flame monitoring by means of ionization current sensor electrode, IRD 820, IRD 1020 or UVD 971. Safety time MV 3 sec. Replacement for Honeywell / Satronic TTI 790 and MMI 810 Mod.33, MMI 810 Mod.55.