When connecting a water source to a boiler, the supply pipe shall have which of the following?

When connecting a water source to a boiler, including both a backflow preventer and an intermediate atmospheric vent is essential for maintaining a safe and compliant plumbing system. The backflow preventer functions to prevent the reverse flow of water, which could lead to contamination of the potable water supply. This is particularly important in boiler systems where chemicals or high temperatures might be present that could adversely affect the drinking water quality.

The intermediate atmospheric vent is also crucial because it helps to relieve any pressure buildup that can occur within the system. It ensures that the water supply remains at safe atmospheric pressure, which is vital for the overall operation of the boiler and helps to prevent any potential hazards such as ruptures or leaks caused by excessive pressure.

In contrast, the other options alone do not fulfill the comprehensive safety requirements needed for connecting a water source to a boiler. A pressure relief valve is important, but it primarily manages pressure within the boiler itself rather than addressing cross-contamination from backflow. A single check valve, while useful for preventing backflow, does not provide the necessary level of protection that a dual system with both a backflow preventer and an atmospheric vent does.