T1, T2 and T3 are climatic conditions in which ur chiller/AC and/or heat pump are to be used. Basically the temperature ranges are as below;
T1: moderate climate, ac/chiller: 18–43 deg C, heat pumps: -7 to 43 deg C.
T2: cold climate, ac/chiller: 10–35 deg C, heat pumps: -7 to 35 deg C
T3: hot climate, ac/chiller: 21–52 deg C, heat pumps: -7 to 51 deg C