Thermocouple-based gas valves immediately extinguish the flow of gas when a pilot goes out in e.g. a pilot fed hot water heater. This has been standard for decades.
Pilot lights have not been used in gas furnaces in decades. Everything has been electronic ignition since the 80s at the latest. In fact they have been outlawed in some locales for close to 40 years.
Who said the pilot light was out?
> Pilot lights have not been used in gas furnaces in decades. Everything has been electronic ignition since the 80s at the latest. In fact they have been outlawed in some locales for close to 40 years.
And the baby-boom produced how many homes with pilot lights? Thermostats are often upgraded on existing homes without touching anything else, and every single home I've lived in was built decades ago still having original HVAC.
It is not "totally safe" for your furnace to start in an unoccupied home, particularly after it's been off for an extended period. It's not impossible for critters to have setup shop in the warm space near a pilot light, and in an unoccupied home there's nobody to even smell what would be an obvious problem before it becomes a crisis.