Plumbing headaches

The electrical work we did last summer was fun, but the plumbing was not. Electrical wiring is pretty simple, for the most part. If you can keep a mental model of the three conductors (hot, neutral, and ground) and make sure they’re always connected properly, you’ve got 90% of it. And there aren’t that many different types of wires and conduits, at least in our house.

But plumbing is a different beast.

There are two completely separate systems, supply and drain, and they use completely different piping and design rules. Then there are the different types of joints: PVC solvent, crimped (PEX), and threaded (there are more, but these are the three we used). Of these three, the PVC solvent and PEX joints were reliable and worked perfectly the first time in every case. The threaded joints were much worse: at least half of them leaked the first time and had to be redone. One of these threaded joints, in the cold water supply line to the bathtub, started leaking recently after six months of apparently good behavior. We had used the thin, white teflon tape on the joint, but even after retaping the joint it still leaked. The next thing we tried was joint compound, a sticky paste that has fixed this type of problem before. But not this time: it still leaked. Finally we resorted to some special, extra thick gray teflon tape designed for stainless steel pipes (the pipe in the leaky joint was stainless steel). This did the trick.

This special gray teflon tape is not available in typical hardware stores, to the best of my recollection. We got it at a wholesale plumbing supply house that normally deals with professionals in the trade. They gave us an account last summer when we told them we were plumbing an entire house. One of their advisors sold us the special tape for use on the pressure pump we bought from them, and it has fixed several leaky joints now.

This is an example of one of those things you learn about housebuilding that you can’t get from books, but only from a combination of luck plus trial and error.

The other plumbing headache we had was venting to the roof. Drain vents are required to let air into the drains so they will move freely, and to let sewer gases out. We didn’t want to punch lots of holes through the roof, so we used air admittance valves (AAVs) on all fixtures, which let air into the drains. But you still need to let sewer gases out, and for that you need at least one vent pipe that exits above the roof. So late last fall we put a hole through the roof above the upstairs sink and vented the sink through a pipe that terminated about a foot above the roof. It was immediately obvious that the vent was working, because the sewer gas (actually gas from the septic tank) coming out of the pipe was overpowering at first. It was so strong it could be smelled on the ground, nearly 20 feet below.

So the venting problem was now replaced by a smell problem. We ended up buying a device called an Odor Hog, which is essentially a charcoal filter that fits over the vent pipe. The smell can still be detected when you’re up on the ladder near the vent pipe, but not on the ground. Thank the internet for that solution; we’ve never seen it in stores.