PING TMHM: Bottom entry bog cistern inlet valve

[Tim Watts]

Got to help a relly out -

Couple of questions:

Current one is sealed in with some sort of gunk on the bottom entry hole. After I've scraped that off, what's a recommended sealant to use?

Fernox LS-X or something with a bit more "stick" like Geocell TheWorks (MS polymer I think, stickier than silicone) - or something else.

The other thing - do all bottom entry valves have the same threaded section length? The pipe runs straight in with a tap connector on the isolator valve so there is no "give" for slight differences.

Sorry to sound thick - only used side entry valves before.

I'm thinking of a

as I have one at home and love it. Brass threads and a good clean shutoff. Not sure yet if there's room, as the fill entry is on the same side a sthe flush handle so it's a bit crowded in there!

[Tim Watts]

Meant I have the side entry version of that...

[Tim+]

I've never used anything. The supplied washers have always worked for me.

Tim

[Jabba]

Tim Watts wrote

Bet the gunk is something that's been used instead of a proper washer in a past repair.

[DerbyBorn]

Clean surfaces, new sealing washers and don't overtighten should do the trick. I would only use a sealant if there was an obvious moulding flaw that would make me think the washers would not do the job.

[Tim Watts]

Thank you all!

Yep - I have only ever added a smear of LS-X to the bottom washer on the rather large flush-downpipe connector, because it's a large area and a weedy plastic nut.

I have never had cause to daub tons of the stuff on!

[Roger Mills]

As others have said, if you clean up the surfaces, the supplied rubber washers provides a sufficient seal without using any 'gunk' of any sort.

The threaded portions are *not* all made equal! I fitted one which was a bit longer than the one being replaced, and I had to shorten the supply pipe - a bit of a pain!

They're not all the same height, either - and the replacement needs to be the same height as the original. Some - such as the SF one which you cite - are adjustable for height. You need to adjust the height before fitting it to the cistern - it's virtually impossible afterwards.

[Tim Watts]

Gawd I was afraid of that... The supply pipe is about 5" exposed coming up through some tiled boxing in - and the pipe is painted. Modding that is a non starter...

Adjustable? Really... I had not looked that hard. My side inlet one is but that's not exactly hard because it does not have to seal.

Thanks for making me aware of that - going to look a bit harder...

Basically the existing valve is dripping. I could replace the rubbers and hope but it's a s**te valve anyway - takes forever to fill. And I said "I have a Fluidmaster, they're rather good..."

[Tim Watts]

Oh - I misunderstood... The threaded part is not adjustable (so needs to be identical in my case, re pipework mods impractical).

But the internal unit height is... OK - with you now.

[Tim Watts]

Or perhaps it is:

(Figure 5).

I shall have to get one and have a look - returnable easily if no good...

[Ian Jackson]

I've just had the misfortune to have had to replace a bottom-entry inlet valve, For various reasons, what should have been a one-hour job took all day.

Apart from eventually having to make life 'easier' by removing the whole cistern, one of other my trials and tribulations was getting the bottom of the valve assembly - and the bottom-exit overflow pipe (which I'd also had to detach in order to remove the cistern) - to seal, despite having removed all the old washers and gunk.

In desperation, I solved the problem by abandoning all the rubber washers, and used self-amalgamating tape wound around and around (well stretched) over the top 1/4" of the thread, and over the flange. This prevented the tape rubber from spreading outwards as the nut was tightened. Both valve and overflow then sealed first time.

[Roger Mills]

As you say, the threaded part is not adjustable - but I suppose that if it's too long, you might be able to put some extra washers inside the cistern to raise it up a bit. *Don't* cut any off the end - it's a special shape, and won't seal if you do!

As you surmise, what *is* adjustable on some (but not all) is the vertical length of the column inside the cistern. It's sort of telescopic, and you have to rotate one tube relative to the other in order to change the length. The one I fitted was quite stiff to turn, requiring one tube to be tightly gripped by one hand and the other tube by the other hand. I couldn't have done that once it was installed. It needs to be the right length so that the gubbins is above water level by at least a defined margin, but still fits under the lid.

They *all* have an adjustment for water level - with a screw to turn which changes the float height at the point of cut-off.

Hope that's clearer!

[The Medway Handyman]

I never use anything - unless there is an obvious bump in the ceramic around the hole - only come across that once.

If possible, cut back the pipe & use a flexible tap connector. Much easier to align & get a perfect seal.

[Tim Watts]

Thanks Dave,

Makes me wonder why it's full of gunk now!

That would be easier - sadly it is a non starter as there's so little exposed pipe.

I'll see if I can match the existing length.

Cheers,

Tim