HVAC: EPA 608 Certification Study Guide Updated 2025 with complete solution

Recover - to remove any refrigerant in any condition from system and store in external container without necessarily testing or processing in any way What are the leak repair requirements for comfort cooling appliances and commercial appliances containing 50 pounds or more of refrigerant? - The leak rate exceeds 15% in comfort cooling appliances How does a centrifugal purge unit work? - A centrifugal purge unit takes its suction from the top of the condenser, removes the air from the system, and returns the refrigerant to the evaporator. Does refrigerant go out of the system in low pressure or does air and moisture go in? Why? - A low-pressure system operates in a vacuum (below atmospheric pressure) to enter the refrigeration system. ASHRAE Standard 15-1994 - Requires refrigerant sensor that will sound alarm and automatically start ventilation system in occupied equipment rooms where refrigerant from leak will concentrate At what point in the system should you charge a low pressure system and what should you start the charge with? - Charge through the evaporator charging valve as this is the lowest point on a low pressure system. First charge the system with vapor until the refrigeration saturation temperature reaches 36 degrees F or the vapor pressure reaches 16.9" Hg vacuum Bubble Point - Occurs when saturation temp in condenser changes refrigerant from vapor to liquid Compound Gauge - Typically blue and measures low pressure (psig) and vacuum (inHg). Compressor - Takes low pressure, low temp vapor and changes it to a high-temp, high-pressure, superheated vapor and delivers it to the condenserCondenser - Rejects heat from system and changes refrigerant from high-temp, high-pressure vapor into high-pressure, high-temp liquid Describe two ways to speed up recovery - Pack the recovery cylinder in ice and/or apply heat to the appliance. Recover as much as possible in the liquid phase. Dew Point - Occurs when saturation temp in evaporator causes refrigerant to change from liquid to vapor Evaporator - Absorbs heat into system from space to be cooled. Absorption of heat causes refrigerant to boil. Upon leaving, refrigerant changed to low pressure, low temperature vapor Find pressure for R-22 at 70 degree F. - 121.4 psi Find the pressure for R-12 at 80 degrees F. - 84.4 psi Foaming at start-up may be found in what component? What does this mean? - Refrigerant in the oil will cause oil foaming in the compressor at start-up High Pressure Gauge - Red and measures high side (discharge) pressure. 0 to 500 psi How can you check if a tank contains excess air or non-condensables? - Check pressure inside recovery tank after allowing temp of cylinder to stabilize to room temperature After removal of liquid, about how much vapor will remain in the system on a 350 ton R-11 chiller? - 100lbs How can you release trapped refrigerants in the oil? - Necessary to heat and tap compressor with mallet several times or use vacuum pump How can you speed up the vapor recovery process on Type III systems? - A heater on the recovery vessel side will help evacuate the vapor fasterHow many inches of mercury vacuum is required for HCFC-22 appliances containing more than 200lbs. of refrigerant using equipment after Nov. 15th, 1993. - 0 Inches Hg How must you recover refrigerant from a parallel system? Why? - Isolate a parallel compressor system in order to recover refrigerant. Failure to isolate a parallel compressor system will cause an open equalization that will prevent refrigerant recovery