Ever wish you had one of those expensive temperature-controlled faucets in your shower my wife did. Since there is a lot of truth to the saying, "happy wife, happy life," I shelled out the money for one. It worked reasonably well, but was a constant source of problems over the years.
Naturally, I took it in the garage and took it apart.
There is one faucet to control the volume of hot water; one to control the volume of cold water and the middle one that actually controls the temperature mix. Each of the faucets has the usual o-rings and compression washers, with the middle mixer also having several extra parts to handle the temperature control. Oddly, the o-rings and compression washers never gave me trouble.
That middle section was a different story though. The piece at the bottom of the picture above:
Over time, it led to low volume and erratic operation because the calcium would sometimes flake off and increase the flow, or grow and decrease it. I got pretty good at adjusting it until it plugged up so much that I couldn't adjust it any further. The hot was maxed out and the cold was turned down so low that the shower didn't have enough volume.
The brains of the device is this piece in the middle:
I guess I could have soaked the pieces in vinegar for a couple of WEEKS because regardless of what you read on the web, it take a LOT of time to dissolve the calcium from a faucet. Then searched every hardware store for 20 miles to get the right size o-rings and compression washers to replace the ones in there because just putting it back together would guarantee a leak and more work.
I chose the path of the lazy homeowner and just bought a new Moen shower faucet that I could easily order parts for and not have to worry about European manufacturers' parts lists and supply chain bullshit; not even mentioning the expense of that pursuit.
Putting the new Moen in was quite the experience though. In case you haven't done that ... yet, you have to tear out the wall on the opposite side to get to the assembly. Then, working from both sides, you have to mount the faucet and re-plumb the water lines to fit it. Nothing ever matches anything else when you're changing manufacturers.
I cheated though. Way back when the house was built, the hot and cold lines were reversed by a mistake the plumber made. That was fixed with some inventive plumbing that didn't even come close to fitting the new faucet. Yes, I could have taken that apart and gathered a collection of fittings to do it over, but since they have really good hoses now for hooking up faucets, I just took the lazy homeowner's way out (again) and bought the hoses and fittings to do it in a way that any self-respecting plumber would panic over.
The cross-over in the middle through the 2x6 is to reverse the hot and cold due to the plumbing mistake that I mentioned. I plan on putting a metal shield over that so I don't make the mistake of putting a screw through the hoses in the future when I close the wall.
The new faucet worked fine and all is well with the world.
Net, if you are thinking about one of those fancy faucets, think a little longer. If you have well water or excessive calcium deposits on your toilets or sinks, it might be a bad idea. If you don't want to have to go through the hassle of a new faucet and a tight job installing pipes; maybe the one you already have is good enough. If you have one of the big names in plumbing in the US, you can get dress kits for it to change the look when SHE gets tired of it and wants to change the look.
That's a heck of a lot easier than what I went through. Think about it for a few years before actually doing it.