A backflow preventer used in a boiler system should be located in the:

In a boiler system, a backflow preventer is crucial for preventing contaminated water from flowing back into the potable water supply. This is particularly important because it helps maintain the integrity of the drinking water system by ensuring that any water that has been used or treated within the boiler does not contaminate freshwater sources.

The correct placement of a backflow preventer is on the make-up water line to the system. The make-up water line typically brings in fresh water to replace any water that has evaporated or been lost due to system leaks. By installing the backflow preventer here, the system effectively blocks any potential backflow from the boiler into the municipal water supply, ensuring that only clean water enters the boiler and that any contaminated water remains in the boiler system.

Locating the backflow preventer in this position is in compliance with plumbing codes and safety regulations designed to protect public health. The make-up water line is a point of vulnerability where backflow could occur if there’s a drop in water pressure or other malfunctions in the system. Hence, the backflow preventer acts as a critical barrier against such risks.