GB884804A - Improvements in or relating to burner control apparatus - Google Patents

Abstract

884,804. Controlling burners. MINNEAPOLIS-HONEYWELL REGULATOR CO. Oct. 6, 1960 [Oct. 12, 1959], No. 34335/60. Class 75(1) [Also in Group XL(b)] A burner control apparatus comprises a fuel leak detector 19 which, when the burner is not operating, operates in conjunction with a flame detector 28 to prevent starting of the burner if a fuel leak is detected. The leak detector 19 comprises a valve 20 which is open when deenergized, a fan 21, an igniter 24 and a burner tip 23. If fuel leaks past the main burner valve 13 when closed it is drawn by the fan over the igniter 24 and burns at the tip 23. The flame detector 28 is therefore actuated and energizes a flame relay 29 to open contacts 33, 34 and to close contacts 35, 36. The open contacts 33 prevent energization of a main burner control relay 39 when a call for heat is made by a thermostat 37; the open contacts 34 prevent energization of an ignition transformer 18; the closed contacts 35 energize through contacts 41 of de-energized main relay 39 a heater 48 for the bimetal element 47 of a safety lockout switch 45 so that the switch opens after a predetermined time; and the closed contacts 36 merely connect the main burner valve 13 to open contacts 43 of the main relay 39 and are therefore ineffective. In the absence of a leak the contacts are as shown when the burner is inoperative. On a call for heat, thermostat 37 energizes main relay 39 and heater 48 of lockout switch 45. Contacts 42 close to complete a holding circuit for the main relay 39 and contacts 43 close to energize a pilot fuel valve 16, the ignition transformer 18 and the valve 20 which therefore closes to make the fuel leak detector 19 inoperative. If the pilot burner 14 ignites the flame detector 28 energizes the flame relay 29; contacts 36 close to energize the main fuel valve 13; contacts 34 open to de-energize the transformer 18 and contacts 33 open to de-energize the heater 48 of the lockout switch 45. The flame detector 28 is a Geiger tube condition sensor having a pair of electrodes in an ionized gas or a photovoltaic or photo-emissive cell.