Which control is responsible for ensuring the flame stays lit in a boiler?

The flame failure control is essential in boiler operations because its primary function is to detect whether the flame in the boiler is present and stable. If the flame goes out for any reason—such as a sudden change in fuel supply, a blower failure, or a drop in combustion air—the flame failure control system acts swiftly to shut down the burner. This is crucial because an unattended and unlit burner can lead to an accumulation of unburned fuel, posing significant safety hazards including explosions or damage to equipment.

In contrast, other controls like high limit temperature control are used to monitor the temperature within the boiler and prevent overheating by shutting down the burner when excessive temperatures are reached. Low water cutoff is designed to prevent the boiler from operating when the water level drops too low, protecting the boiler from overheating and damage. Modulation temperature control regulates the relationship between boiler output and the heating demand but does not specifically ensure that the flame remains lit.

Thus, the flame failure control is specifically tasked with maintaining safe combustion conditions by ensuring the burner operates properly and that the flame is always lit when required.