Abstract: An electric control device for a central heating boiler which is provided with a water pump or an air ventilator (6), a burner with an electrically operated shut-off valve (5) and an electric control circuit comprising a supply transformer (1) and a series circuit connected to the secondary winding of said transformer and composed of the control winding (4) of the shut-off valve (5), the contact of a room or regulator thermostat (3) and, if present, the contact of a maximum thermostat (2) and in which the water pump or air ventilator (6) is connected in parallel with the primary winding of the supply transformer. The control device comprises a circuit to be connected to the contact of the room or regulator thermostat (3) including a high resistance value series resistor (R.sub.s) to be connected into the mains supply circuit of the boiler, a relay (13) with a normally open contact (k) connected in parallel to said series resistor (R.sub.