Honeywell Maxon 27729 Flame Rod for OVENPAK 400 Series Burners

The ignition unit was flashing code 7 Flame Rod Shorted. I removed the igniter/pilot assembly and found a bridge of carbon across the electrical portion of the ignitor. I cleaned the ignitor and re-installed the assembly and everything worked fine, for 2 days. Same problem. I removed the assembly again but this time I also took apart the pilot.. Flame rod shorted to ground: Flame rod shorted to ground: Shorted or mis-wired flame rode wiring. Defective flame rod. Delta T inlet/outlet high: Temperature rise between supply and return is too high. Inadequate boiler water flow. Verify that pump is operating and that pump and piping are sized per Section VI of this manual. Return temp higher.

Flame rods are positioned so that one end end of the flame rod is in direct contact with the burner flame and the other end is connected to the furnace ignition board. Once the board sends 24vac to the gas valve to open, it monitors current flow on the flame sensing rod.. Flame sensors fail when: They short out due to a cracked insulator.. Clean the rod with a scotch brite pad and use the ohm setting to check the rod length to the other end, should be less than 1 ohm with no cracks or tracking to ceramic. Then with meter in series flame microamps should be 2 or more. If less than 2 usually flame size or ground although sometimes internal problem in control.