High
Too much excess air, insufficient draft
Fix: Reduce air, adjust barometric damper
Low
Too little excess air, excessive draft
Fix: Increase air, adjust barometric damper
Low
Too much excess air, insufficient draft
Fix: Reduce air, adjust barometric damper
High
Fix: Increase air, adjust barometric damper
Flame impingement, poor air/fuel mix, blocked heat exchanger, nozzle issues, draft problems, too little excess air, damaged burner head
Fix: Increase air, check nozzle, clean heat exchanger, verify draft, replace burner head
Low
Underfired
Fix: Verify firing rate & draft
High
Dirty heat exchanger, high excess air, overfired
Fix: Clean Heat exchanger, optimize air/nozzle
High
Dirty heat exchanger, high excess air, overfired
Fix: Clean Heat exchanger, optimize air/nozzle
Low
Underfired
Fix: Verify firing rate & draft
Low
Leaky or undedrsized chimney, thimble, stack or breech, chimney obstruction, draft regulator adjustment
Fix: Seal leaks, clear chimney, adjust draft regulator to manufacturer’s spec.
High
Oversize chimney, cold outdoor temp, miss-adjusted draft regulator, air entering combustion chamber
Fix: Adjust draft requlator, close/seal leaks in appliance
High
Insufficient air, poor fuel atomization, dirty burner, air in fuel
Fix: Increase air, check pump pressure/nozzle