In the combustion heater, combustion air system, what prevents too much air from entering the heaters as air pressure increases?

In a combustion heater's combustion air system, the function of the combustion air relief valve or differential pressure regulator is crucial for maintaining optimal air levels entering the heater. This component is designed to manage the pressure of the combustion air, allowing it to regulate how much air can enter the system.

When air pressure in the system increases, the relief valve activates to prevent an excessive amount of combustion air from being introduced. An appropriate air-to-fuel ratio is essential for efficient combustion, and excessive air can lead to inefficient burning, increased emissions, and even potential overheating of the system. The differential pressure regulator effectively ensures that the system operates within its designed parameters, promoting safety and efficiency in the heating process.

This specific functionality is what makes this answer the correct one regarding the prevention of too much air entering the heaters. Other components listed may play supportive roles in the overall air management system, but they do not specifically serve the purpose of regulating excessive air pressure in the same way.