Normal Furnace Operation Back   Home
  1. The service switch is “on”.
  2. The remote switch is turned “on”.
  3. There is a “call” for heat (interior, domestic water, engine coolant).
  4. The igniter is glowing.
  5. The combustion air intake fan in the furnace is running.
  6. The system circulation pump is running.
  7. The fuel pump delivers fuel.
  8. The compressor turns on.
  9. The fuel valve opens and fuel is drawn into the air-aspirating nozzle.
  10. The fuel is atomized and sprayed into the combustion chamber.
  11. Combustion is started.