What is the last step to take before filling a boiler?

The last step to take before filling a boiler is to check the boiler vent. This is critical to ensure safe operation because the vent allows for the proper expulsion of air from the system, which is vital when filling the boiler with water. If the vent is blocked, it can create pressure build-up during the filling process, which could lead to dangerous conditions.

Ensuring that the vent is clear also aids in preventing any back pressure, allowing the water to fill the boiler efficiently and safely. Proper attention to the vent helps maintain the integrity and performance of the boiler system, ensuring that it operates effectively without the risk of air pockets or other related issues.

Other steps are important in their own right, such as checking the pressure gauge or sealing openings, but confirming that the vent is unobstructed is crucial right before the boiler is filled. This ensures that all safety and operational parameters are met for a successful filling process.