What can be used to pressurize a chiller system before opening it for a non-major repair?

The most appropriate choice for pressurizing a chiller system before opening it for a non-major repair is nitrogen. This is because nitrogen is an inert gas that does not react chemically with the components of the chiller. When pressurizing a system, it's important to prevent contamination and avoid introducing moisture or substances that could cause corrosion or damage to internal components.

Using nitrogen allows technicians to safely check for leaks without risking the integrity of the system by introducing gases that could potentially react with any residual refrigerant or lubricant. Additionally, nitrogen can be used to clear out moisture or other contaminants, making it ideal for preparation before repairs.

Controlled hot water is typically not used for pressurization purposes; instead, it may be used for heating or de-icing applications but would not provide the necessary pressure needed for a system check. R-409A, being a refrigerant, is not suitable for pressurization and can complicate the repair process while adding safety and environmental concerns. Compressed air, while pressurizing, often contains moisture and oil contaminants that can harm the system, making it an unsuitable choice for pressurizing a sensitive refrigeration system.

Overall, nitrogen stands out as the best choice for this procedure due to its properties and the