What does a positive pressure reading on a boiler draft gauge indicate?

A positive pressure reading on a boiler draft gauge indicates that the furnace pressure is above atmospheric pressure. This is significant because it means that the combustion gases are being effectively contained and managed within the combustion chamber, allowing for proper combustion and heat transfer within the boiler.

When the pressure inside the furnace exceeds atmospheric pressure, it ensures that combustion air is being adequately drawn in and that the flue gases are being expelled efficiently through the flue. This helps in maintaining optimal combustion conditions, reducing the risk of backdrafts or flue gas leaks, which can pose safety hazards.

Other choices do not accurately reflect what a positive pressure reading signifies. For instance, cooler boiler temperature would not necessarily relate to the draft gauge reading, nor would an increased water level or excessive steam build-up be directly indicated by a draft gauge measurement. Each of these scenarios affects the boiler's operation but does not specifically correlate to the meaning of pressure readings on the draft gauge itself.