Call for heat (programmer + thermostat) Fan Runs
Pressure Switch senses fan running and
Pliot light Lights
PCB senses pilot light burning and
Main Gas Valve Opens
The back of the Manual has a fault finding chart.
People say the Printed Circuit Board suffers dry joints and sometimes they're right but not always. You can take the bottom cover off the boiler (one screw under a flap at the bottom) and tap the PCB and other parts with the handle of a wooden spoon to check for bad connections.
If the pilot fails to light suspect the pressure switch.
Make sure the over temp stat has not popped - button reset hole underneath. May have popped because temperature control set too high. Put it on 3 or 4 - not max.
Peccavi
December 2008
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