Seat Nuts: They'll Save You Time and Money

One day, my bathtub's cold water valve handle started to leak. I tightened the handle, then did a visual check. It still leaked. I tightened it tighter, but before long, I somehow knew that this was not the problem. I bought a new valve at Home Depot, and even with the new valve, it kept leaking. I kept buying washers and nuts and magic spells, but it kept leaking, with no hints as to why. When I looked at the rubber washer on the valve, it was ripped up. So I bought a new washer -- again -- and closed the valve. It kept leaking. I took it apart again, and saw that the new rubber washer was ripped up -- again!

I concluded that the pipe in the wall had to be replaced because I suspected that the interior of that pipe was damaged, thus damaging the valve’s washer. This meant I had to tear open the wall from top to bottom, and buy a whole new pipe system, as they were all soldered together. I was discouraged, but I knew I had to do it.

I went to Home Depot convinced that I had to buy a 12-foot length of pipe with a T in it at the right spot, along with all related soldering supplies, a torch and what-not. I almost didn't ask the next question, but I thought, "Why not? There's a million-to-one chance that I didn't know something about this problem."

So I described the problem to a pro. Without batting an eyelash, he said, "You probably need a new seat.”

“A new what?”

He found me a "seat nut" not far from where he was standing, but told me I needed a seat wrench too (which was another few steps away), unless I wanted a plumber to do it. When I saw that the seat wrench was nine dollars, I couldn't imagine a plumber charging less than that, so I decided to buy it.

The nuts are round and threaded on the outside, and come with four-sided or six-sided holes in the center. One end of the seat wrench has three fixed sizes for square holes, and the other end comes with three hex sizes.

At home, when I pulled out the seat nut, I saw that it was definitely damaged, one edge with tears and slots in it. This was probably caused by the absence of a washer that had completely worn down, causing the valve’s cylinder to rub against the seat.

After you put pipe thread compound on the threads of the seat nut, it's a good idea to carve a small stick into the shape of a pointed knife and fit the seat nut onto it, to start the threading of it into its place. Gently turn the stick until you can see that it is going into the threads. This will prevent "cross-threading," which is the crooked placement of a nut, and which would permit another leak, and damaged threads.

I spent the few seconds required to put in the new seat nut, installed the valve, turned on the water, and was convinced anew that nobody had put a spell on my house. I reported to my wife that the job was done, and successfully so, and then said, “That’ll be 90 dollars, please, Ma’am.” She laughed. That’s our code talk for “We saved 90 dollars, today .”

Actually, when you think about it, we probably saved even more, considering I was ready to remodel the bathroom.

The following video shows how to replace a rubber washer in a valve. What they didn't show you is the seat nut inside the part still attached to the sink. The seat nut is what comes in contact with the rubber washer, and it's what puts the worn grooves in that washer.