From inside (document excerpt):
25HPA6 Performancet Series 2 Stage Heat Pump with Puronr Refrigerant 2 to 5 Nominal Tons Installation Instruction NOTE: Read the entire instruction manual before starting the installation. SAFETY CONSIDERATIONS Improper installation, adjustment, alteration, service, maintenance, or use can cause explosion, fire, electrical shock, or other conditions which may cause death, personal injury, or property damage.
Consult a qualified installer, service agency, or your distributor or branch for information or assistance. The qualified installer or agency must use factory-authorized kits or accessories when modifying this product. Refer to the individual instructions packaged with the kits or accessories when installing. Follow all safety codes. Wear safety glasses, protective clothing, and work gloves. Use quenching cloth for brazing operations. Have fire extinguisher available. Read these instructions thoroughly and follow all warnings or cautions included in literature and attached to the unit. Consult local building codes and current editions of the National Electrical Code ( NEC ) NFPA 70. In Canada, refer to current editions of the Canadian electrical code CSA 22.1. Recognize safety information. This is the safety-alert symbol !!. When you see this symbol on the unit and in instructions or manuals, be alert to the potential for personal injury. Understand these signal words; DANGER, WARNING, and CAUTION. These words are used with the safety-alert symbol. DANGER identifies the most serious hazards which will result in severe personal injury or death. WARNING signifies hazards which could result in personal injury or death. CAUTION is used to identify unsafe practices which may result in minor personal injury or product and property damage. NOTE is used to highlight suggestions which will result in enhanced installation, reliability, or operation. Indoor Thermostat Control Options Model Infinity Control Yes Standard 2 stage Thermostat Yes 25HPA6 ! WARNING ELECTRICAL SHOCK HAZARD Failure to follow this warning could result in personal injury or death. Before installing, modifying, or servicing system, main electrical disconnect switch must be in the OFF position and install a lockout tag. There may be more than 1 disconnect switch. Lock out and tag switch with a suitable warning label. ! WARNING UNIT OPERATION AND SAFETY HAZARD Failure to follow this warning could result in personal injury or equipment damage. PuronR refrigerant systems operate at higher pressures than standard R- systems. Do not use R- service equipment -22 -22 or components on PuronR refrigerant equipment. INSTALLATION RECOMMENDATIONS NOTE: In some cases noise in the living area has been traced to gas pulsations from improper installation of equipment.