If a boiler is equipped with an automatic non-return valve, it must be located _______?

The correct placement of an automatic non-return valve is crucial for proper boiler operation, as it prevents the backflow of water and reduces the risk of water hammer, which can damage the boiler and piping system. This valve needs to be situated close to the boiler shell to ensure maximum effectiveness, as it allows for immediate response to any changes in pressure or flow conditions.

When the valve is located near the shell, it creates a more efficient barrier against backflow from the discharge system, effectively isolating the boiler from downstream conditions. This placement helps maintain the desired pressure and water levels within the boiler, promoting safe and efficient operation.

In contrast, positioning the valve at the highest point of the boiler, at the inlet, or at the discharge would not provide the same level of protection or efficiency, potentially allowing unwanted backflow or pressure fluctuations that could interfere with the boiler's operations.