Gas Flue through return duct Home › Forums › Public Forums › Gas & Gasfitting › Gas Flue through return duct This topic has 3 replies, 4 voices, and was last updated 22 years, 11 months ago by Harold Kestenholz. Viewing 3 reply threads Author Posts 9 Jan 2002 at 8:42 pm #278182 andrew williams Is the installation of a gas hot water heater’s PVC exhaust flue through a cold return duct allowed/dangerous?ThanksMarcel 9 Jan 2002 at 9:04 pm #297956 Robert Stephen MortonParticipant marcelg. PVC exhaust flue? A/C Duct? Turn the HWS off & call a Licensed Gasfitter. 10 Jan 2002 at 1:05 am #297957 SylvanLMPParticipant This has to be the most dangerous posted Question I have ever read any place. All I can say is thank God these folks do not live near me as I hate seeing body bags in front of a home. 10 Jan 2002 at 9:08 pm #297958 Harold KestenholzParticipant Also, running combustion vents through ducts is not allowed by code. Author Posts Viewing 3 reply threads You must be logged in to reply to this topic. Log In Username: Password: Keep me signed in Log In