P.Water Boiler with Continuous Ignition (Standing Pilot) and Tankless Heater. See Figure 43.
1.Normal Operation
a.Thermostat calls for heat or low limit senses water temperature below set point.
b.Vent Damper (if used) opens as stated in Vent Damper Sequence of Operation.
c. Gas Valve(s) is energized allowing main gas flow and ignition of Main Burners.
d. After Thermostat or low limit is satisfied Gas Valve(s) is
2.Safety Shutdown
a. Limit: Automatically interrupts main burner operation when water temperature exceeds set point. Maximum allowable temperature is 250°F. Normal operation resumes when water temperature falls below set point.
b. Blocked Vent Switch. Automatically interrupts
main burner operation when excessive vent system blockage occurs. Control is a multiple use device. If blocked vent switch is activated do not attempt to place boiler in operation. Correct source of blockage and reset blocked vent switch.
c. Flame
d. Thermocouple: senses pilot flame and causes gas valve to turn off main burner and pilot burner gas flow should pilot burner flame extinguish.
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