R290 propane refrigerant

R290 propane refrigerant is refrigerant-grade propane used as the sealed-circuit working fluid in some heat pumps. Product documents may use the R290 code when they describe refrigerant type, charge, low GWP (global warming potential), safety clearances, flammability precautions or service requirements. It is not the heating water in the system, not a general F-gas (fluorinated greenhouse gas) label, not proof that a heat pump is efficient, safe, compliant or suitable for a property and not something a householder should handle or vent.