We had a very tough issue to detect and solve. Sewage smell from air return vents and only at certain times and vents. The folks from Top Choice Plumbing came in and swiftly diagnosed the problem. They noticed that the previous plumbers had not capped a sewage air pipe. The problem was fixed and we are very happy. The biggest issue was diagnosing what and where the problem was from. They were very knowledgeable. I highly recommend them for any plumbing jobs.