How do you test the operation of the fire-eye on a gas-fired boiler?

To test the operation of the fire-eye on a gas-fired boiler, shutting off the gas supply is a valid method to ensure that the fire-eye is functioning correctly. The fire-eye, or flame sensor, is designed to detect the presence of a flame in the combustion chamber. When the gas supply is turned off, the fire-eye should register the absence of flame, leading to a shutdown of the boiler for safety reasons.

This process confirms that the fire-eye is effectively monitoring the flame state. If it continues to signal the presence of a flame when none exists, that indicates a malfunction, which could lead to dangerous situations. Proper operation requires the fire-eye to react appropriately to changes in flame state, including turning the boiler off when there is no flame detected.

In contrast, increasing the gas supply, adjusting the thermostat, or cleaning the fire-eye may not provide a reliable assessment of the fire-eye’s operational integrity and could potentially lead to unintentional hazards. These actions either don't directly test the fire detection capabilities or could alter the combustion conditions, which would not accurately reflect the fire-eye's functionality.