Anti syphon valve thingy

[Jay Bee]

Hello all, my heads when flushed has a small discharge to the outside which means my antisyphon valve is not working and probably needs a clean. Does the part in the photo , unscrew/pull off or is it all just one piece? And if it does come off and it’s stuck what’s the best way to tackle? Answers much appreciated.

 

[nigel1]

Looks like your valve is missing bits

 

[VicS]

Hello all, my heads when flushed has a small discharge to the outside which means my antisyphon valve is not working and probably needs a clean. Does the part in the photo , unscrew/pull off or is it all just one piece? And if it does come off and it’s stuck what’s the best way to tackle? Answers much appreciated.

I dont recognise the make but some certainly unscrew.

Inside you will probably find a small replaceable "duck bill" valve

 

[stu9000]

Mine, which looks similar (without the hose attachment) had a nipple cover that screwed closed.

 

[Ian_Edwards]

If liquid is coming out of the overflow, then the duck bill (or reed valve) has failed in the open position.
If you can get the overflows pipe off and access the valve, and you are lucky, you'll be able to clean the valve , which is made out of soft rubber like material, in hot soapy water, and reassemble it. Or just replace the whole assembly, they are not expensive.
I also wonder where the pressure to force liquid out of the overflow is coming from. I'd be checking the seacock and the sanitary pipe down stream of the anti syphon valve for a blockage. There should be minimal pressure in the sanitary pipe, just enough to lift the waste over the loop. Once over the high point gravity should take the waist down to the water level.
Is it possible that the heads have been pumped with the sea cock closed?

 

[bluerm166]

Related to this topic - whatever the manufacture ,why would you make this fitting as an arc shape - rather than a full half circle so that the hoses come off in the vertical ? Perhaps it makes manufacturing easier ?