In commissioning a new secondary refrigerant system without an automatic bleed valve, what is the procedure to remove air?

The procedure to remove air in a secondary refrigerant system without an automatic bleed valve involves finding the highest point in the system and installing an air bleed vent. This is because air tends to rise to the highest points within a system due to its lower density compared to refrigerants. By installing a bleed vent at the highest point, any trapped air can be released, ensuring that the system operates efficiently without air entrapment, which can lead to inefficiencies and potential damage.

This method effectively allows for the expulsion of air during the filling process or after the system has been filled, making it a crucial step in commissioning and maintaining the system's reliability. Properly managing the air within the refrigerant loop is key to ensuring optimal thermal transfer and reducing the risk of system disruptions.

Other methods such as installing a manual valve at the lowest point would not effectively address the air that accumulates at the top of the system. Using a vacuum pump is primarily a method for evacuating moisture and non-condensables before charging the system, rather than for managing air. Filling the system with refrigerant does not address the presence of air, and could actually worsen the situation by trapping air pockets within the system.