A plumber is tasked with installing a new boiler in a commercial building. The boiler's makeup water connection has the potential for backflow of treated boiler water into the potable water supply. Which of the following backflow prevention devices, if any, is typically required by the National Plumbing Code of Canada (NPC) for such a connection?

Question: A plumber is tasked with installing a new boiler in a commercial building. The boiler's makeup water connection has the potential for backflow of treated boiler water into the potable water supply. Which of the following backflow prevention devices, if any, is typically required by the National Plumbing Code of Canada (NPC) for such a connection?

Answer options:

• Atmospheric Vacuum Breaker (AVB)
• Double Check Valve Assembly (DCVA) ✅ Reduced Pressure Principle Assembly (RPBA)
• No specific device is required if the boiler pressure is lower than the potable water supply pressure.

Correct answer: Reduced Pressure Principle Assembly (RPBA)

Explanation: For boiler makeup water connections, especially in commercial settings where chemicals may be added to the boiler water, a Reduced Pressure Principle Assembly (RPBA) is typically required by the NPC. This is due to the potential for a severe health hazard associated with contaminated boiler water. An AVB is for backsiphonage only, and a DCVA is for non-health hazards. Low boiler pressure does not eliminate the backflow risk from backsiphonage.