Pressure reducing valve jammed?

[JohnD]

I have one of these

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It supplies cold (from mains) to the shower of my guest room.

Between guests there is no usage through the valve, and it tends to jam shut.

In the past I have screwed the pressure adjusting screw in and out, and it frees off. However now it stays jammed.

I suppose I will have to take it off and have a tinker, but has anyone dealt with this problem before and have any tips?

edited: it is a Caleffi.

 

[JohnD]

well I pulled it off.

I was not able to open the diaphragm chamber with hand tools, but I found that the adjusting plastic plug pushed against a meaty spring which I imagine is pushing on the diaphragm to counteract the water pressure. I screwed it all the way in (max pressure setting) and I heard the valve open with a bit of a pop (though it didn't close again when I slackened off to min pressure, so it might still be stuck).

On reassembly, the gauge shows 1bar with guest room taps open, and 3.5bar with them shut or nearly shut (I presume this is static pressure).

I have adjusted it so that gauge pressure is stable at 1bar (taps open) even if kitchen sink taps (upstream of the reducer) are opened. The static pressure (taps shut) drops from 3.5 to 3 bar if the kitchen taps are opened. Guest room tap flow and pressure "feels" and looks about the same between hot and cold taps now. The hot is fed from a tank about 10 metres above, so 1 bar is about right.