InthispapertheΔ-Ytransformationofalinearelectriccircuitisintroducedtosimplifythecomputationofnetradiantheatexchangeonasurfaceofanenclosurewiththreesurfaces.Theillustrationofthetransformationisgivenbysolvingsixproblemstakenfromthetextbooks.Somediscussionconcerningthepossibilityofextendingthetransformationmethodtoenclosureswithmorethanthreesurfaces,andtheconditionforapplyingthenetworkmethodarealsopresented.