INTERMITTENT SEWER SMELLS
A recent customer complained of sewer odor in her upstairs master bathroom each morning after everyone had showered. Upon arrival, I asked: "Precisely where is the odor strongest in the morning?" She led me to a specific part of the bathroom; alongside a commode and bidet combination. We could not detect or smell anything unusual. The bathroom appeared to have been recently remodeled. We capped off all roof vents except the one serving the shower in question. My helper was set up and ready on the roof. My job was in the bathroom scouting for evidence of escaping smoke. As soon as the smoke entered the pipes, I saw a heavy stream of white smoke being pushed out from the center of the bidet's bowl. It reminded me of the genie coming out of Aladdin's magic lamp. There it was, either the trap had failed or there was no trap under the floor for this fixture. We removed the bidet and discovered that a trap was never installed. The plumbing was roughed-in for a bidet with an integral trap. The bidet that was ultimately installed at the finish stage did not have the needed trap.
When a slug of wastewater tumbles down a drain it displaces sewer gases. The displaced gas rolls back over the top of the flowing water; traveling back towards the water's source. The gas will exit the system at the first opportunity, taking the path of least resistance. The water seal in a fixture trap is what holds those gases within the drain and vent system forcing the moving gases to travel up to the roof vents. Our bidet was acting as a vent because there was no trap protection and those sewer gases were allowed to escape to the indoor of the structure. When someone took a shower, the waste gases would start their journey towards the roof vent, but found an easier escape route along the way—through the bidet's untrapped drain. Not only did we create revenues with our test; we also sold the repair.
Test time: 1 hour, 2 technicians. Materials: one smoke bomb. Equipment: blower used to push the smoke. Testing charge: $450. Additional work sold: $400.
Another interesting project was a record recording studio. Sound studios are filled with electronics, computers and soundboards. The walls were soundproofed with special materials then carpeted over. There were electrical chords everywhere. Nothing could be moved and the walls could not be opened unless absolutely necessary. I climbed a stepladder and removed a ceiling panel to take a look topside—a nest of wires and ductwork. This customer too, had called numerous plumbing companies about a severe sewer odor in the studio.
I proposed a smoke test for $450. They agreed, it was the best offer they had. We turned off all HVAC systems so that smoke would not be inadvertently circulated throughout the building, possibly nullifying the test. The building was evacuated and we began. The attic space above the ceiling panels quickly filled with smoke. A roof vent for an adjacent bathroom had been cut inside the attic space and never redirected to outside air. The bathroom was venting indoors just above the suspended ceiling. That pipe could not be seen during our initial look topside. It was buried behind ducts and wires. In less than ten minutes we had the answer.
Test time: 1 hour, 2 technicians. Materials: one smoke bomb. Equipment: blower used to push the smoke. Testing charge: $450. Additional work sold: $300.
