What Is An Air Pressure Switch?
The air pressure switch in a boiler ensures that waste gases are being expelled, before allowing to fire up. The fan creates a draft which allows harmful gases to be released from the boiler via the flue.
The reasons A Boiler’s pressure switch is failing.
It’s important to be aware of that any air flow issue will cause a air pressure switch to not allow the boiler to fire.
Commons reason a boiler will not fire:
The air pressure switch notices the pressure differential isn’t great enough then it shuts off the boiler.
If your switch won't turn on, this might be a sign your tank pressure is above your switch's cut-in pressure. Try running some water elsewhere in the building to reduce pressure below the cut-in level. You can also try gently tapping on the pressure gauge, the switch, and the tank.