Refrigerant Pressure Temperature Chart | HVAC Refrigeration

High Performance HVAC

20 years ago

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Refrigerant Pressure Temperature Chart | HVAC Refrigeration - This page offers a temperature-pressure relationship chart for use in working with HVAC Systems that use R-410A, R-22, and R-134A. Additional refrigeration information and resources are located below the chart. For more information and comprehensive articles on HVAC Refrigeration see our Refrigeration Category.

High Performance HVAC Refrigerant Pressure Temperature Chart

PT Chart for Common Refrigerants

Refrigerant Pressure Temperature Chart - PT Chart for R-410A, R-134A, and R-22

These are currently the three most widely used refrigerants on the market today for HVAC applications in residential and commercial use. R-22 refrigerant is the king and used widely in the residential and commercial markets followed by R-134A which is used in commercial applications for chillers and in wide use in car air conditioning systems. R-134A replaced R-12 for automobile air conditioning systems. R-410A is currently being phased in for residential use as the phase period for R-22 draws nearer.

The pressure of the refrigerant corresponds with the temperature. Using a PT chart or pressure temperature chart one can determine the pressure or the temperature of the refrigerant. To properly charge an HVAC air conditioning or heat pump system one needs to use the PT chart or pressure temperature chart, a set of manifold gauges, and a thermometer or solid-state temperature sensing device.

Every set of manifold gauges in use today have the pressure-temperature chart or PT chart on the dials of the gauges so an HVAC technician need not carry a pressure-temperature chart or PT chart with them. The gauges used for R-22 differ slightly from the gauges used for R-410A as the pressures and temperatures are different for each type of system.

Metering Devices - Subcooling and Superheat - Refrigerant Oil

Depending on the type of metering device the HVAC technician will use either the superheat method, the subcooling method, or use a chart provided by the manufacturer of the equipment to ensure that the charge in the system is correct. If the unit is not a split system but a package unit then a weigh-in of refrigerant based on the manufacturer’s data can be done without using charts or the superheat or subcooling methods. The HVAC technician may decide to use these methods to double-check the charge for the weigh-in to be sure the charge is correct.

It is also important to note that the oil for R-410A and the oil for R-22 are different oils and precautions taken so that the oils do not mix. This is a good reason why an HVAC technician needs to carry two different types of gauges, one for R410A and one for R-22. This prevents cross-contamination of oils from an R-410A system to an R-22 system. The oil for R-134A is also different than the other oils used for R-22 and R-410A and it is important not to mix oils from other systems or systems with different refrigerants and oils.