I have the same issue with my Janitrol furnace. Even thought the igniter lights the piolet, the control circuit does not sense that the piolet is lit. It can take quit some time before it decides that the piolet is lit and fires up the furnace. If it takes to long the ciruit gives up and kills the gas resulting in no heat. Cleaning the thermo couple off with steel wool every couple months is the only way I know to fix this.