A heat exchanger (3; 5) comprises a gas flow path extending from a gas inlet side (4) to an opposing gas outlet side (6) of the heat exchanger, and at least one heat exchange coil (8; 8a, 8b) extending through the gas flow path and being configured for allowing heat exchange between a fluid flowing through the heat exchange coil (8; 8a, 8b) and a gas flowing through the gas flow path. The at least one heat exchange coil (8; 8a, 8b) comprises a refrigerant inlet portion (10) having an inlet terminal (12), an refrigerant outlet portion (14) having an outlet terminal (16), and a heat exchange portion (18) connected between the refrigerant inlet portion (10) and the refrigerant outlet portion (14) allowing fluid to flow from the refrigerant inlet portion (10) through the heat exchange portion (18) into the refrigerant outlet portion (14). The refrigerant inlet portion (10), the refrigerant outlet portion (14) and the heat exchange portion (18) are arranged within the gas flow path so that gas entering at the gas inlet side (4) first passes the refrigerant outlet portion (14), then the refrigerant inlet portion (10) and finally the heat exchange portion (18) before leaving the gas flow path at the gas outlet side (6). The refrigerant inlet portion (10) is provided by a single inlet tube section (9), the heat exchange portion (18) is provided by at least two heat exchange tube sections (20, 22) and the refrigerant outlet portion (14) is provided by at least two outlet tube sections (24, 26) connected in parallel, wherein the volume (R) ratio between the volume (Vin) of the refrigerant inlet portion (10) and the sum of the volume (Vex) of the heat exchange portion (18) and volume (Vout) of the refrigerant outlet portion (14) is between 1:3 and 1:7, in particular between 1:4 and 1:6.