Are these screw heads damaged?

[KFried]

Hi there,

The pics show the two screws that regulate the cold/hot flow to my shower thermovalve(paraffin). They appear stuck and I don't want to force'em with a flathead.
One is close to the max 'out' position, the other one close to the max 'in' postion. But not sure how much more give there is on either.
I am getting hotter than usual mix and trying to help the valve, before I look/find for a replacement cartridge(unlikely, 15+ old model)

Are the heads damaged? Or is there a special key? Would lubricant work to loosen? At the extreme: can I unscrew the whole screw assembly by working on the nut?

TIA

 

[KFried]

Educated meself more by googling and found out these are the valve stops and now I have a better idea what's inside and will try to remove and service them.
But anyways, any advice on the matter still appreciated.

Godspeed to you all.

 

[pasadena_commut]

In response to the title question, those do indeed appear to be damaged brass screw heads. As opposed to some odd special slot which has a matching key.

Rather than "service" them, you might be better off finding replacements, even though it might be difficult. If that was a common valve Danco or the like may make a replacement even if the original manufacturer no longer does. The American Standard three handle set in our tub was installed in the late 1950's and they were very commonly used, so aftermarket stems are still available.

If you cannot find manufacturer's info remove the stem with the center mostly out and take it to a plumbing supply house to look up a match. They might not have one in stock, but if it exists, you can order one. Or look here:

https://www.kissler.com/shop/stem-cartridges
https://www.leakyfaucetguide.com/stem-cartridge-finder/

Is the valve body sturdy looking and well fastened to framing members? Can't tell from the picture. Important not to damage something by twisting the valve body with the stem, as the stem might be stuck and require a fair amount of oomph to turn. It doesn't look like it is locked in with calcium deposits though, so more likely to come out easily.

 

[Ferdinand]

Educated meself more by googling and found out these are the valve stops and now I have a better idea what's inside and will try to remove and service them.
But anyways, any advice on the matter still appreciated.

They are stop valves, allowing you to shut off either/both the hot/cold water supply lines to this faucet. Those are really handy so you can work on the valve core without needing to shut off water to the entire house.

I had a bit of an adventure with mine back in Jan 2018, my first post on this forum.
https://www.plumbingforums.com/threads/multiple-shower-issues.12477/

One bit of caution though. If they've never been touched, like mine, they worked great to shut off the water when screwed in all the way tight. But only the first time! When I unscrewed mine to open the flow again, one of the stop valves now leaked!

Mine each had a rubber O-ring seal, allowing the stop valve to turn inside its brass mount. But one of those O-rings now leaked.

2nd problem. I turned them all the way back in to shut the water off again until I could source a replacement. But now one of them would no longer fully close off the water. So I ended up after all needing to turn off the water to the entire house. Sheesh.

The ancient plastic "foot" that seals off the water had crumbled. Moral of the story, have replacement parts handy before messing with this stuff.

Mine were a different style than yours. This is what mine looked like:

 

[KFried]

Thanks for the replies: I realize now the stops might be kaputt, so I won't proceed unless I have replacements ready(doubtful).
The valve itself is a VADO, UK-made, apparently. I'm in Toronto, btw. I'm at the third cartridge(in 17 years) and the current one might be on life-support, but not 100% sure.
I'm looking up a new valve+trim, thinking Moen or Grohe, so far. My setup is handheld+rain shower with a diverter. I wish I knew better and bought something more common way back.

Thanks again.