When the operating control (A) calls for heat, it energizes the main gas valves (B) in both gas trains starting burner operation. The burners will operate until the operating control is satisfied. The high limit control (C) will stop burner operation in case of excessive steam pressure (steam boiler) or excessive boiler water temperature (water boiler).
The low water
Should one of the pilot flames become extinguished the pilot safety switch (E) to which it is connected would shut off the gas supply to that pilot and to the main gas valves and burners it is serving (100%
Fig. 56
WIRING DIAGRAM - 15 THRU 24 SECT. BOILERS
THERMOCOUPLE CONTROL SYSTEM
CANADA ONLY
70
