How long is the pre-purge on a low pressure boiler?

The pre-purge duration for a low-pressure boiler is typically set at 90 seconds. This interval is crucial for ensuring the safety and efficiency of the boiler system. During the pre-purge phase, the system clears out any residual combustion gases that might be present in the combustion chamber or exhaust system. This reduction of flammable gases helps to prevent potential explosions or backfires when the burner is ignited.

A 90-second pre-purge allows sufficient time for the air to circulate and properly ventilate the combustion area, significantly enhancing the safety of the startup process. Manufacturers and safety regulations often dictate this duration to standardize operations across various systems, ensuring that boiler operators can maintain consistent safety practices and pre-operational checks before ignition.