Arizona Plumbing Practice Exam

When connecting a water source to a boiler, what must the supply pipe include?

1. Single shut-off valve

2. Backflow preventer and intermediate atmospheric vent

3. Expansion tank

4. Pressure relief valve

The correct answer is: Backflow preventer and intermediate atmospheric vent

When connecting a water source to a boiler, including a backflow preventer and an intermediate atmospheric vent in the supply pipe is essential for ensuring safety and compliance with plumbing codes. A backflow preventer is crucial to protect the potable water supply from contamination due to the possibility of reverse flow from the boiler, which can occur under certain conditions. This device prevents any water that may become contaminated within the boiler from flowing back into the public water supply. The intermediate atmospheric vent is part of a system that helps mitigate pressure changes within the water supply line, further enhancing the safety of the boiler system by allowing excess pressure to escape, preventing potential damage or hazards. This dual system works effectively to safeguard water quality and maintain the integrity of both the boiler and the water supply. While single shut-off valves, expansion tanks, and pressure relief valves are important components in their own right, they do not address the specific concern of protecting the drinking water from potential contamination during the connection of a water source to a boiler, which is the primary function of the backflow preventer and intermediate atmospheric vent.