Plumbing - compression or push-fit?

[ctdctd]

I have a loo cistern which is weeping from the water inlet - either at the pipe / cistern joint or from the washer sealing the hole in the cistern.
Nipping the pipe up fixed it for a while (5 years!) but it's started again and nippy no worky.

Access is very poor so I'm thinking strip it all down to have a proper look.

It has an elderly compression flexi hose from copper pipe to the cistern which I would like to replace with one including an isolator valve.

The copper pipe tail is short and I don't think I can easily chop a length off to get a fresh bit of pipe to connect to.

So - what do you think would work most reliably - a new compression flexi or a push fit flexi directly in place of the old?

Please don't say neither - replacing the copper pipe tail will involve floorboards up and a blowtorch!

[Sheets Tabuer]

Plumbers mate?

also new washers.

[Scolmore]

Push fit uses o-rings, which like anything rubber will deteriorate over time (that said, I think JG Speedfit has a 50 year guarantee). A compression fitting crushes a metal olive in order to form a seal, so nothing to deteriorate. Of course, a braided flexi hose also uses rubber, so the type of connector seems somewhat moot to me.

Being able to solder end feed fittings is a useful skill indeed. I'd teach it in schools if I had any say in that sort of thing.

Edit to add, the plastic threads on the cistern inlet are your most likely cause of the problem. Be prepared to replace the fill valve. Bonus points if you can find one with a brass thread.

[ctdctd]

Sheets Tabuer said:

Plumbers mate?

also new washers.

Indeed - all this will be done when I strip it down.
However, I'd like to replace the flexi connector at the same time to add an isolator valve to make the job easier next time, hence the question.

[ctdctd]

Scolmore said:

Push fit uses o-rings, which like anything rubber will deteriorate over time (that said, I think JG Speedfit has a 50 year guarantee). A compression fitting crushes a metal olive in order to form a seal, so nothing to deteriorate. Of course, a braided flexi hose also uses rubber, so the type of connector seems somewhat moot to me.

Being able to solder end feed fittings is a useful skill indeed. I'd teach it in schools if I had any say in that sort of thing.

I have soldered end feed fittings in the past but, in this case, access is so poor that I'd rather not attempt it!

[Sheepshanks]

Push fit needs the pipe its pushing on to be in good nick.

If there's a compression fitting aready and you don't want to cut the pipe stub then you're a bit stuck - but presumably you're also going to have to reuse the existing olive so getting a reliable seal might be trickly. If this is what you're doing I'd lash Fernox LSX all over the olive and hope for the best.

[OutInTheShed]

If the copper tail is short, I would be thinking to use the existing compression nut and olive on a new compression flexi, or an isolator valve. then a new flexi.

unless access is good, cleaning up a used end of a pipe to take a pushfit seems like awkward and risking failure to me!

Bear in mind that isolator valves are on the list of 'things which leak a bit and annoy me sometimes'.

[Lotobear]

The easy first step would be to try PTFE tape on the joints, usually works IME.

[Simpo Two]

Sheepshanks said:

If there's a compression fitting aready and you don't want to cut the pipe stub then you're a bit stuck - but presumably you're also going to have to reuse the existing olive so getting a reliable seal might be trickly.

Old olives can be cut off using a junior hacksaw at an angle, or (modern answer) a Dremel. Then clean up the pipe and use a new olive. But as you say the pipe may be slightly compromised from its previous squeezing.

If the old stub is going to be reused there's always a slight risk IMHO, but you may as well try it before ripping the floor up

[Sheepshanks]

Simpo Two said:

Old olives can be cut off using a junior hacksaw at an angle, or (modern answer) a Dremel. Then clean up the pipe and use a new olive. But as you say the pipe may be slightly compromised from its previous squeezing.

Well, you could even use an olive puller! Whatever you do, if the end of the pipe has flared it'll be tricky to get a new olive on.

[Belle427]

I'd just use another quality compression flexi.
If it leaks at the old olive fernox is your friend as listed above, sometimes a few wraps of ptfe will also work.

[Magicmushroom666]

Wrap the ptfe around the olive though not the threads, they have no bearing on the seal.

[Aluminati]

Lotobear said:

The easy first step would be to try PTFE tape on the joints, usually works IME.

This.

[KTMsm]

I have never understood putting the isolation valve on the part that is most likely to need replacing

Separate iso valves make sense to me

[ctdctd]

By way of thread closure.

Following the replies on here, I rushed out and got a new compression fit flexi and a cistern filler valve with a brass inlet.
The leak then fixed itself for another year..........

However, started dripping a pint a day before Christmas which turned into a pint an hour over Christmas so back to the top of the to-do list it went!

With nothing to lose, I first tried removing the old flexi but left the olive in place. Cleaned it up, added four turns of PTFE tape and a bit of liquid PTFE sealant and hurrah!, it's all working as intended!

So thanks for suggesting olive reuse was possible and also that brass cistern inlet connectors are still a thing!