plumbers... leaky flush pipe

[Davi]

Got a bit of a problem with the ensuite toilet. The hidden cistern is mounted (through necessity) quite low, only problem is that the bend in the flush pipe is only just finished by the time the seal and compression fitting go on to the bottom of the cistern. I thought I'd get away with it, but no, it's just determined not to seal. Tried a couple of flush tubes but same issue, I think it's just too close to the bend and so the tube isn't perfectly round at the point the seal needs to be made.

Ideas for creating a good solid seal? I thought I'd just knock one up out of two lengths of pipe and a gentle 90 deg solvent weld, but of course, the flush pipe is a few mm larger diameter than a 32mm solvent weld...

I've tried silicon as an emergency "till I come up with something better" seal and that failed LOL

[Ricky_M]

Try using a 32mm male/female elbow with a straight coupling on the male end of the elbow, should give some extra width.

[Ferg]

I'd get a nice chunky tapered rubber seal from a compression waste fitting (32mm) and then once you've found EXACTLY where it needs to sit bind over the top of the rubber seal with a LOT of PTFE tape. So much that the nut will only just clear it. You may find the thread jumps, so get a nut with plenty of thread on it.

[Deva Link]

A good smearing of Fernox LS-X. Let it set for an hour or so before it gets water on it. Buy it in Screwfix - half the price it is at B&Q.

[Ferg]

Deva Link said:

A good smearing of Fernox LS-X. Let it set for an hour or so before it gets water on it. Buy it in Screwfix - half the price it is at B&Q.

The problem with LS-X in this instance is it's silicone content tends to allow the threads to jump on the nut. Not helped by the flexibility of the syphon/flushvalve tail.

[Deva Link]

Ferg said:

Deva Link said:

A good smearing of Fernox LS-X. Let it set for an hour or so before it gets water on it. Buy it in Screwfix - half the price it is at B&Q.

The problem with LS-X in this instance is it's silicone content tends to allow the threads to jump on the nut. Not helped by the flexibility of the syphon/flushvalve tail.

I guess it should be possible to restrict it to the necessary mating surfaces - the inside of the compression ring and the top outside edge of it. Did our cloakroom recently and the compression ring looked very feeble but it sealed fine with LS-X.

[Davi]

cheers guys, didn't think of a nice chunky rubber seal, try that with the PTFE first, if still fails I'll try a bit of everything LOL. The rubber seal that came with was kind of puny looking at best, indeed I thought it may give me a problem when originally fitted.

Oh BTW Ricky - great minds... I tried that, unfortunately just too big then!