Abstract: A passive stream regulating system applicable to air-flue gas or water-flue gas heat exchangers, preferably natural gas balanced flue or natural flue home heaters and home boilers, which allows to attain non-over oxygenated stoichiometric mixture conditions. The system is included by small diameter tubes or other geometric systems formed by small channels, to produce a strong laminarization of the aerodynamic flow established within the venting tube, which are located in sections of the conduit or passage of incoming cold air to the combustion chamber of the exchanger or in sections of the conduit or passage of hot flue gases released to the environment.