Jason Grupillion - Jun 27, 2014

Tech Tip: F09 Error Causes


Many people often inquire about an F09 Error. Common causes of F09 Errors include:

  • No spark

  • Clean rectification probe

  • Check venting for restrictions or obstructions

  • Condensate backup

  • Swirl plate (check for disintegration, cracked or broken fins)

  • Incoming static gas pressure

  • Dynamic gas pressure (pressure drop should be measurable between ½“  and 1” WC)


However, there is a step that not many contractors know about: checking the burner tube. If clogged or restricted, the burner tube can cause an F09 error. Over time, a boiler accumulates intake air debris that often gets caught up inside the stainless steel mesh of the burner tube. When this happens, the system cannot deliver the proper amount of air and gas to maintain a flame.  A flame may be created for a short period of time, it may flutter a bit and then ultimately burn out. The only way to properly clean this debris out is to remove the burner tube and flush it either in a sink or with a hose. After flushing the burner tube, allow time for it to dry before attempting to light the unit. We highly recommend taking this step prior to making any adjustments to the throttle on the gas valve. After all, what’s the point of increasing the amount of fuel supplied, if all that fuel can’t find its way to the flame?

Written by Jason Grupillion