| 摘要 |
<p>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 (Rs) 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 (Rs) and means (10,11,12) for controlling the relay (13) in such manner that the water pump or air ventilator is put into operation only upon the closing of the contact of the room or regulator thermostat and the opening of the contact of the maximum thermostat respectively through the closing of the contact (k) of the relay (13).</p> |
