Additional vent requirements Goodman GM9C / GC9C 2 Stage ECM Furnace Install/Spec/Service Goodman GM9S96 / GC9S96 Single Stage ECM Furnace Install/Spec/Service Goodman GMEC96/GCEC96 2 Stage ECM Furnace Install/Service/Spec Goodman GMES96/GCES96 Single Stage ECM Furnace Goodman GMVC96 / GCVC96 Var. Speed 2 Stage Furnace W/Comfort Bridge Install/Spec/Service Goodman GMVM97 / GCVM97 Mod Furnace W/Comfort Bridge Install/Specs/Service Goodman GR9S96 Furnace Single Stage R32 Furnace Install/Spec Goodman GRVM97 Modulating R32 Furnace Installation Goodman GSX13/GSX14 Specs/Accessories/ Install Manual