When an oil burner is served by a tank, what must be installed if the fuel supply line comes from the top of the tank?

When an oil burner is served by a tank and the fuel supply line originates from the top of the tank, it is essential to install an anti-siphon valve. The purpose of the anti-siphon valve is to prevent the unintentional siphoning of fuel from the tank, which could occur due to atmospheric pressure changes or other factors that create a vacuum in the fuel line.

When the fuel supply line is positioned at the top of the tank, it increases the risk that fuel could flow back down into the tank or even spill out in undesirable ways if there is a failure in the system. The anti-siphon valve acts as a critical safety feature, ensuring that fuel flow is only allowed in one direction, thus safeguarding against spills, leaks, or contamination that might otherwise occur from backflow scenarios.

This safety measure is particularly important in preventing potential fire hazards associated with fuel by ensuring that the oil remains securely in the line as intended to be delivered to the burner.