shower thermostatic cartridge filter/screen cleanout - Rohl

[onyaw]

We have a "Rohl Country Bath" thermostatic shower where I want to clean-out the screen on the hot side (low flow i think from crud that came through our system a while ago and the filter/screen wasn't fully cleaned).

The rough (A4913BO) looks like the photo below, except that ours is an older version where the service stops don't have handles on the end, they turn with a wrench and are marked with a "+" for orientation. I watched the plumber do this last time enough to know the correct position of the service stop, but not carefully enough to see how he turned the inner nut to get to the screen.

Will the turning the service stop sufficiently stop the water flow so that i can unscrew inner nut to get at the filter/screen, or do i need to shut down master valve? Also, once I turn the service stop, do I need to hold that in place with a wrench while i unscrew the inner nut?

Thanks much for any pro tips

 

[Geofd]

If that's an older valve if you can isolate the valve before the stops it might not be a bad idea, to replace the stops also that way everything is the same age and replaced at the same time

 

[breplum]

Is it like this? really need a pic to know what to do.
More than likely, you need to turn all water to the building off in order to service.
The integral stops are only to service the main cartridge.

 

[onyaw]

sorry no pic handy (don't have the trimplate off at the moment). It looks more like the picture i showed, except the service stops don't have a handle/stem sticking out, just place to grip and turn on the circumference (and a plus sign showing which way is open). but i think i will turn off the house water, to be safe. thx. again.