Trane IntelliPak WEHE Series Installation, Operation And Maintenance Manual page 67

Flame Failure
In the event that IC board 4U18 loses the "proof-of-flame"
input signal during furnace operation, it will make one
attempt at reignite. If a flame is not reestablished within
the 10 second trial period, 4U18 will shut down and lock
out the ignition /combustion control circuit. (Combustion
blower motor 4B11 continues to run as long as a heating
requirement exists and control circuit switch 4S24 is ON.)
Once locked out on flame failure, the IC board will not
reactivate the ignition/combustion control circuit until it is
reset manually. To do this, press the reset button on the
front of the IC board case.
A set of relay contacts are available for external use for
heat fail (Information Only).
Important: The modulating gas heaters are factory
adjusted for the proper air/gas ratio at
minimum and nameplate rated firing MBH
for most areas in the country.
RT-SVX35H-EN
System Start-up
67