I don't have a picture but about ten years ago a tech found a 90+ furnace that a home owner had tied the flue into the plumbing drain surprisingly it worked just fine-that is until a trap in a sink that was not used very often dried up & let all the exhaust into the house it almost killed the guy's wife she was a widow I wonder if the guy killed himself doing that?hmmmmmmmm I didn't have the nerve or lack of compassion to ask if he died from co poisoning.