Flames ignited to heat water as seen through a gas boiler’s viewing window.

Boiler sparks but will not light. A Boiler can be a fickle mistress at times. Boiler ignition circuits have been known to be elusive in its diagnosis.

Boiler sparks but will not light be a common boiler problem on steam boilers.  A simple problem is a stuck low water cut off control.  Tigger handle a few times and it may clear the gunk out of the float switch allowing for the float to free itself for proper operation of ignition circuit.

There are 2 types of ignition circuits on steam boilers. 1 is the infamous standing pilot and 2 is the Boiler spark ignition type.  Spark ignition gives that “tic tic” sound when sparking for ignition.

Basically, the same sound your home stove makes when turning on the gas. Then the standing pilot gives the distinctive swoosh sound when igniting.

However, on a standing pilot boiler if the pilot goes out from wind or a defective thermocouple then no heat will be present. Defective Baso valves can also play a role in no heat scenario on a standing boiler piloted system.

Back to spark ignition circuits, a boiler that sparks and will not light can be contributed to a defective spark control board.  Don’t be fooled.  Let me explain, in order for a spark ignition circuit to operate properly a solid ground needs to be sensed.

On the pilot assembly, there is a ground that rectifies back to the spark control board.  Make sure connections are tight.  Also, if a wire is attached to burner where pilot assemble is attached remove wire and sand the spot where ground wire attaches and reconnect.  Many times, that quick fix will return your heat to normal.

The gas valve especially Honeywell gas valves have a ground terminal spade connector on its valve body. Sometimes a ground added to the gas valve to the spark board ground burner also will return your heat to normal.

Thanks for reading.



Schedule HVAC Service

Call or email to talk to a technician. Landlords & Tenants, please fill out this form to request HVAC work on tenant properties.