S Your new gas furnace may have been installed in one of two. ways, as a direct-vent (2-pipe-Fig. 2) application or as a. non-direct vent (1-pipe-Fig. 3) application. S In a direct-vent (2-pipe) application,your furnace uses air. from outside the home for combustion and ventsflue gas to the. outdoors.
For the biological concept, see Anti-predator adaptation. A defence mechanism is an unconscious psychological mechanism that reduces anxiety arising from unacceptable or potentially harmful stimuli. Sigmund Freud was one of the first proponents of this construct.
Notes. â 1  Paulhus, D.L., Fridhandler B., & Hayes S. (1997). â 2  Cramer, P. (1991). â 3  Special issue on Defence mechanisms. â 4  Kernberg, O. (1967). â 5  Vaillant, G. E. (1977). â 6  Plutchik, R., Kellerman, H., & Conte, H. R. (1979). â 7  American Psychiatric Association. â 8  Northoff G, Bermpohl F, Schoeneich F, Boeker H.(2007).