The present invention relates to a 3-d channel gas heat exchanger. The 3-D channel gas heat exchanger includes a plurality of heat exchange plates configured to have heating surface units for exchanging heat formed on one sides of the heat exchange plates and a plurality of passages and that are formed in between the plurality of heat exchange plates and wherein the plurality of passages comprise, first passages configured to convey a first fluid having a first temperature through the first passages, second passages configured to convey a second fluid through the second passages for transferring heat to the first fluid having the first temperature and third passages configured to prevent freezing in the second passages by transferring heat to at least some of the second passages when a temperature (T) of the second fluid is below a predetermined temperature value (Tref).