hello:

So I had a plumber replace an old (1930s) american standard hot shower single handle cartridge and seat because it was slowly leaking at the handle and head and also banging when turned on and off.

We got a high quality, heavy brass american standard replacement and installed it, complete with new packing nut, stem, seat. It worked fine from the start, the only immediate issue was it would not allow water to flow out when installed so the plumber tightened up the packing nut then it worked fine, although the handle was noticeably harder to turn on and off than the other 3, and it needed to be turned quite a bit further before water comes out. The tap when turned on low would also pivot back slightly, as if under strong internal pressure, and try to turn itself off when partially opened.

Now, the water hammer has returned, but not as loud as with the original cartridge, only in that specific tap but there are no leaks anywhere. The noise occurs when you turn the tap on slowly just as the water begin to flow and also when you turn it off. None of the other taps make such a noise. I left the water off for 30 min then just turned the tap on and off 3 times in a row, no noise but the 4th, 5th and 6th time, the banging returned when turning off and on if that helps..

Im really confused what happened because if the replacement part was faulty I thought it would bang right away.

Is it possible he turned the packing nut too tightly and if so is the unit unsalvageable? I brought the old part to the plumbing store and they matched it up with this new part so I assume the part is correct and it was brand new, I saw it personally. I tried bleeding all the taps in the house but the problem is still there.

Please help, happy holidays and thank you.



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The packing nut is there to prevent water leaking from around the shaft and to keep some rotational tension on the shaft. It should have no correlation to compression washer/seat issues. To me it sounds like there's a problem with the compression washer or it's retaining screw. Has the cartridge been removed and inspected? Were the new seats identical to the old ones?

Luckily I bought 2 just in case one failed which is shown in the pics. I have not removed the one the plumber installed because I plan on calling him back to assess. The seats look pretty much identical. I mean there may be a 1mm difference on the stem length and its has an extra thread but they look pretty close and the receipt said it the new part was also american standard. Attached are the pictures. Thank you Steve



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I had the same thing happen at a friend's house. I replaced the A/S stems with OEM parts and after a couple months, the hot stem would create a loud vibration, when opened a slight amount. I replaced the washer and this worked for about 6 months and then started happening again. My friend had me change the faucet to a 2 handle ceramic seal style and a separate anti-scald valve.

Than you Steve: My only concern is if this banging will cause a leak in the supply lines or cartidge behind the tile wall. Do you think it could. Attached is the picture of my pipe cutouts behind the wall. The top right pipe is the hot shower handle in question.

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not to worry. those pipes will no be harmed

I did a bit more research and it appears my stem is the american standard re-nu, 5.5 inch stem? It appears I was sold an non OEM part, and I know the original part may be discontinued. Also, there are 2 twisted circles on the original stem but 3 on the replacement. i remember the store clerk guy saying the hot and cold are the same part, is that correct? Does anybody know of a different brand non OEM that would work without banging. I think these are manufactured incorrectly, as washer, seat were brand new and retaining screw was clamped down.

Many thanks

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