Looking for ideas – IF error. Hayward W3H400FDN. Symptoms – runs sensor checks, fan spins up, ignitor glows, gas flows, but no flame (no heat at vent and no whoosh from burner light-off). Runs 3x then IF failure. I took Omni-logic connections off to eliminate this as an option.
What I have done:
1> Replaced gas valve (works, have verified flow during ignition cycle & 24V AC @ valve)
2> Replaced hot-surface ignitor
3> Replaced Flame sensor
4> Checked voltages and fuses
5> Tested flame sensor with torch
6> Removed and cleaned burners and gas orifices
7> Tried two Amazon “like-new” circuit boards – both had different failure (fan didn’t run , i.e. both were worse than my existing PCB)
Any ideas? Should the 24V at gas valve be constant or pulse? Mine seems to supply voltage for only a few seconds – is this normal as part of the start sequence, or could I have a bad transformer (it supplies proper voltage, but I can’t tell if it does so under load). My thought is it must be a bad circuit board, but before I spend $300+ on a new one I wanted to see if I’m missing something else.