syphonic toilet overflow

[Allerdown]

I'm not sure how to correctly fit the black half-sphere washer that seats onto the first chamber in the pan. I can't work out whether in operation the washer slides up/down the pipe it fits over, or is intended to remain fixed.

Should I simply fit it at the extreme lower end of the pipe, and then lower the cistern slowly back onto the pan, relying on friction to not push it up so far up the stem that it no longer seals? Or is it intended to tolerate slight gaps underneath it, because the water pressure above it (and the vacuum below it if working properly) will re-seat it if necessary when it flushes?

I can't find any description of the recommended installation technique anywhere and am not sure whether the shaft of the pipe should be lubricated so the washer can slide. Please can someone (with a long memory) advise.

Thank you.

 

[Hugh Jaleak]

Are you referring to the small domed washer that slides along the thin tube sticking out the bottom of the aspirator? If so, this needs to be an airtight fit where it sits inside under the tail of the syphon, to ensure a seal around that tube which is going into the middle chamber of the pan.

The purpose of that tube is to create a vacuum in the middle chamber of the pan when the flush begins, if the seal isn't made then the pan wont work as designed, and will fill when flushed, rather than the water drop as it should.

Make sure the washer is fit for purpose and not perished. Position it on the end of the tube, and carefully lower the cistern assembly onto the pan, this washer should then be gently pushed up the tube to stop where required and form the required seal. I have never used lubricant, may cause premature failure of the washer, but wetting the tube and washer may assist with movement on installation.

 

[Allerdown]

Thank you, Hugh. Yes, that's exactly the washer I was thinking of, and you have confirmed what I thought was needed. Many thanks.