During pilot trial for ignition the igniter and pilot valve are energized for a set period, often around 10 seconds, and the scanner must prove the pilot. Main flame trial then opens the main fuel valves for another limited period. If flame is not proven in time, the control shuts off fuel and locks out, so unburned fuel cannot keep flowing into a hot furnace.
It's failing on pilot trial for ignition, I can hear the spark but the scanner never picks it up, check the pilot gas pressure.
Never extend the trial for ignition to cover a weak pilot; fix the pilot.
Also heard as
- TFI
- ignition trial
Related terms
Flame safeguard
The control that runs a burner's start sequence, watches the flame, and shuts the fuel off fast if the flame fails.
Pilot
A small flame that lights the main burner and is often used to prove ignition before main fuel flows.
Light-off
The moment a burner ignites, and also the verb for lighting it.
Lockout
A safety shutdown that holds the burner off until someone presses a manual reset.