Is there an easy way to tell what shower cartridge you need by just looking at the end that sticks out the wall?
Shower Valve/Cartridge Identification
Help Identifying this Shower Faucet Cartridge - Home Improvement Stack Exchange
Riobel shower valve cartridge identification
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Maybe I am just talking out my ass but why must they make it so difficult to identify by making you to turn off the main water and removing the part to find the number or taking it to Home Depot to match when they can just simply put a model number on the stem end for anyone to see??? It would be so much easier to order the part or at least check inventory status for the closest supply store before having to remove the whole cartridge.
I'm confused, you have two cartridges in your hand and all the cartridges are in place in the shower valve. Is it a different shower?
If there are no markings anywhere on the valves or handles, You've got two choices: go to your home store and look on the plumbing racks for an identical cartridge (bring the old one with) or go to a plumbing supply store and they should be able to match it. Those guys usually know their stuff. It will be hard to find one online without actually being able to line it up with the old one. Good luck and stay safe out there.
Di Vapor Victoria Plum series
https://www.divapor.com/spares/showers/diverter-cartridge/100mm-two-way-diverter-cartridge-for-victoria-plum-shower-valves.php
Anyone know how to identify the right replacement cartridge for a Riobel shower valve? I don't have the model of the valve. All I have is this install guide that the previous owners of this home left behind.
I had a plumber here for a separate problem, and asked him to look at this shower because the hot water has always had a lot less pressure than the cold. He suggested replacing the cartridge as a first step, but he doesn't work with Riobel usually so he couldnt offer advice on finding the right one since we don't know the valve model.