Rollout Switch
The safety that trips on flame outside the burners.
Furnace Delayed Ignition: Why It Booms on Startup and What to Check
A furnace that bangs or booms when the burners light has delayed ignition, gas building up before it lights. What causes it (gas pressure, burner position, a blocked carryover, bad orifices, a weak igniter), the order to check it in, and why it can't be left alone.
Furnace Flame Rollout Switch Tripped: What It Means and What to Check
What a tripped flame rollout switch means, why you should not just reset it, and how to check the vent, burners and heat exchanger.