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26
XI Start-up and Checkout
Use the following procedure for initial start-up of the boiler:
1) Make sure that the boiler and system are filled with water.
2) Check all new gas piping for leaks and purge piping sections that are filled with air. See Part 4 of the National Fuel Gas
Code for additional information on testing and purging gas lines.
3) Verify that vent system is complete and free of obstructions before attempting to fire boiler.
4) Inspect all wiring for loose or uninsulated connections.
5) Make sure the main burners are seated properly in the rear of burner tray and on orifices.
6) Adjust thermostat to the highest setting.
7) Start the boiler using the appropriate lighting instructions for the gas valve on the boiler on pages 29-32.
8) Upon initial start-up, the gas train will be filled with air. Even if the gas line has been completely purged of air, it may take
several tries for ignition before a flame is established. Once a flame has been established for the first time, subsequent
calls for burner operation should result in a flame on the first try.
9) Observe pilot burner flame:
• See Figure 24 for standing pilot. Pilot burner should produce single steady medium blue flame covering around 3/8”
to ½” of thermocouple tip.
• See Figure 25 for intermittent ignition. Pilot burner produces three flames. The center one should be a steady medium
blue flame covering around 3/8” to ½” of spark electrode/flame rod.
NOTE
SAFE LIGHTING AND OTHER PERFORMANCE CRITERIA WERE MET WITH THE GAS MANIFOLD AND
CONTROL ASSEMBLY PROVIDED ON THE BOILER WHEN THE BOILER UNDERWENT THE TESTS
SPECIFIED IN Z21.13.
25
Safety Control Operation - Standing Pilot and Intermittent Ignition
High Limit - Interrupts main burner operation when the supply water temperature exceeds set point. Maximum allowable tempera-
ture is 250°F. If the high limit opens, the vent damper will close if the damper switch is in the “automatic” position. The circulator
will continue to operate as long as there is a call for heat, regardless of the status of the high limit (if the boiler is equipped with a
tankless coil, the low limit switch will prevent the circulator from operating if the boiler water temperature is too low). Burner
operation automatically resumes when the supply water temperature falls below set point.
Blocked Vent (“Spill”) Switch - Automatically interrupts main burner operation in the event that flue gas spills from the draft
diverter opening. This switch is equipped with a reset button which must be pressed to restore normal burner operation. An open
blocked vent switch is indicative of a problem with the vent system. If the blocked vent switch opens, the cause of the venting
problem must be found and corrected by a qualified gas service technician before the blocked vent switch is reset.
Flame Roll-out Switch - Automatically interrupts boiler operation when flames or excessive heat are present in vestibule. The flame
roll-out switch is a single use device which must be replaced by an identical switch in order to restore normal operation. An open
flame roll-out switch is usually indicative of a plugged heat exchanger. The cause of the flame roll-out must be found and
corrected by a qualified gas service technician, and the switch replaced with an identical one, before the boiler is returned to
operation.