FIELD: ventilation systems. SUBSTANCE: heat exchanger includes tube section for circulation of liquid and finned members secured to outer surfaces of tube sections for increase of heat exchange surface. Finned members are divided into at least two zones 5 and 6 for more effective heat exchange. Tube sections 8 and 9 may be connected with collector pipe lines 16 and with distributing pipe lines 18; thus, after passage of liquid through one zone of fins 5 it is mixed in at least one collector pipe line 16 before delivery of it to distributing pipe line 18 of next zone 6 or in distributing pipe lines of subsequent zones, thus providing for effective temperature control of medium to be heated or cooled. EFFECT: enhanced efficiency. 10 cl, 7 dwg
