Two parts remain as suspects in an intermittent and rare
main burner stoppage before the thermostat is satisfied.
It's either the igniter/lockout control or the 3-wire pilot sensor.
The pilot remains on after the main burner stops. (Then
the furnace shuts down normally, and restarts immediately.)
Any strong hunches? Please share! Time between hiccups
is about 2.5 days.
Thank you,
Herb

wrote:
Two parts remain as suspects in an intermittent and rare
main burner stoppage before the thermostat is satisfied.
It's either the igniter/lockout control or the 3-wire pilot sensor.
The pilot remains on after the main burner stops. (Then
the furnace shuts down normally, and restarts immediately.)
Any strong hunches? Please share! Time between hiccups
is about 2.5 days.
Thank you,
Herb
Hi,
Model of furnace? Is the blower running when main burner stops?
Is your filter clean? Double check it.