A little background on me, I'm new out of tech school, still looking for an apprentice job. In the mean time I'm trying to learn all I can by visiting this site (I've applied for pro, just waiting now) and watching videos on youtube, etc...
This afternoon I was watching one video on YouTube where a guy has a furnace with a spark ignition that won't light. The spark is sparking but not lighting the gas. Eventually he takes a lighter and lights the gas. Watching this has me curious about what safety is in place for no flame on a spark ignition gas furnace? In class we dealt with a standing pilot and hot surface ignitor when we worked with gas, and they both had thermocouples to cut off gas supply if no flame was present, but we didn't learn much about spark ignition. Does a spark ignition use the same safety? If so, why was this guy able to light the furnace with a lighter after no ignition from spark? If anyone has a little time to provide me with some additional knowledge, I'd appreciate it.