Oil Furnace - Starts/Burns Normally but Locks-Out

Oil Furnace

Re: Starts/Burns Normally but Locks-Out

You arrive to find the flame safeguard control locked-out. You reset it and the burner ignites and burns properly, but after about 30 seconds it locks-out again.

CHECKOUT:

1. Check Oil Flow 

• Turn off power to the furnace.
• Remove the oil supply line from the nozzle assembly.
• Gently bend the supply line to be able to spray oil into a cup.
• Place a jumper across the thermostat input to the controller.
• Re-apply power to the furnace.
  • If the burner does not start, press the reset button on the primary control to reset.
• Allow the furnace to pump oil for up to 5 seconds (stop by turning off power).
  • Oil stream should start immediately with the pump motor.
  • Oil stream should be continuous and have adequate pressure.
    • Oil Pressure Inconsistent = Stripped Pump Coupling or Clogged Oil Filter ⇒ Check Pump Coupling and replace oil filter then recheck.
  • Oil stream should be solid red (white foam indicates air).
    • Air in Oil ⇒ Check for loose connections at the oil filter.

2. Test Ignition

• Re-connect the fuel line to the nozzle assembly.
• Initiate a call for heat.
  • If the burner does not start, press the reset button on the primary control to reset.
• Ensure that the oil ignites without hesitation.
  • ​​​​​​​Delayed Ignition = Bad Nozzle, Bad/Mis-Aligned Electrodes or Weak Ignition Transformer.
• After the burner starts, place a jumper across the Cad Cell wire terminals.
  • Still Locks-Out = Bad Flame Safeguard
• ​​​​​​​Monitor the flame while the burner operates.

3. Check Cad Cell

• Disable the call for heat.
• Allow the furnace to shut-off and cool.
• Remove the Cad Cell eye from the burner.
• Use a Cad Cell tester to check the Cad Cell outside the furnace.
  • Should show "Good" when exposed to a light source.
    • Bad  ⇒ Replace Cad Cell
    • Good ⇒ Continue
• Re-install the Cad Cell eye.
• Use a Cad Cell tester to check the Cad Cell with the furnace operating.