🔍 Key Concepts

• Purpose of a pre-purge cycle in an automatic boiler (safety: clearing furnace of unburned fuel/combustibles) • Relationship between air flow, furnace damper position, and firing rate (high fire vs low fire) • Sequence on most automatic burners: air-only purge before any ignition or fuel admission

💭 Think About

• Before any flame is established, what must the burner management system accomplish to prevent furnace explosions? • During a pre-purge, do we want maximum or minimum air flow through the furnace, and why? • After the timed purge is complete, in what general condition should the burner be left so it is ready to light off (think about firing rate and damper position)?

✅ Before You Answer

• Confirm that pre-purge occurs before fuel and ignition are introduced to the furnace. • Check which options describe maximum air flow through the furnace during the purge period. • Verify which answer leaves the system in a safe, stable position to start at low fire after the purge is finished.