Cistern connection to mains.

[Wyliecoyote]

Hello

Experience: DIY plumbing.

i have installed a couple of cisterns and used 15mm compression to the plastic cistern connection, never had a leak. The ends of the pipes appears to be 'chamfered' if that's the correct term, for an olive, not flat like a tap connection, hence the logic.

Recently looked at a couple of leaking cistern connections and these had a tap connector (pro installed) so looks like I've been doing it incorrectly, however both these leaks are at the tap connector,.

I am at the second one now, the first I put a new fibre washer in, but that took some wrangling to get sat correctly due to the 15mm feed being out of line, and not straight (from new!)

So I do it wrong, and no leaks (in many years...) is this a thing, that they just do leak occasionally and I must use tap connectors?

fyi both houses built around the same time, 12 years ago.

thank you in advance for your help.

Nick

 

[joni os]

Fibre washers and plastic threads are a bad mix. I prefer to use plastic push fit with O ring seal , or better get cistern inlet with brass thread.

 

[JCSPLUMBING]

Tap connectors are the correct and only way btw and fibre washers are fine. Done loads of them. If your worried you could smear some v2 jet lube on the washer. Most likely they're cross threaded

 

[Unregistered]

Ok great, at least I know that's thats the correct way. Thanks.

 

[Best]

To be honest, I would say any ball valve or 1/2" tap that comes with a tail that has a tapered end designed for an olive, should only have that method of connection. If you had used a tap connector with a flat washer (of any type), it would be at risk of leaking sooner or later. The sharp end of the tail isn't designed for a flat washer. A flatter faced end of some fill valves & taps is different.

 

[JCSPLUMBING]

I've never seen a fill valve on a cistern to be connected via a nut and olive on the plastic thread

 

[Best]

I've never seen a fill valve on a cistern to be connected via a nut and olive on the plastic thread

Yes, you would have to first tighten the nut & olive onto a brass fitting, but it would be fine if you did. Same as some electric shower connection bends, like on Redring plastic bends.
I previously used a female straight or bend, with ptfe taped jointed to plastic ballvalve tails. But if a flat face on plastic or brass tail I use tap fitting with the 'rubber' flat washer.
Ballvalves on cold water tanks, if tapered tail end, I always use nut & olive connection as it is by far the best.

 

[JCSPLUMBING]

Thanks best. I've used them on float valves in lofts and electric showers. Never even thought about on a cistern to wc

 

[Best]

A lot of them fill valves are not really made for a copper pipe though. I notice many brass ball valves (cheap type) are now coming with their brass tails with a flat end.

 

[JCSPLUMBING]

True. I would definitely be worried about stripping the threads on them tightening olives onto them. Especially brass olives

 

[Staffy85]

iv installed small over sink water heaters which had plastic tails with compression fittings, horrid little things, tap connectors imo would of been a better idea especially wrapped with ptfe tape {wouldnt need to worry about the chamfered edge as it would seal both sides }, dont need to go over board with tightening to get a water tight seal,

 

[WHPES]

Only brass shanks with chamfers are designed to be able to take olives (such as brass float valves for water storage cisterns, and some 1/2" taps).

When you buy a Speedfit tap connector, you get a chamfered washer as an alternative in the packet with the fitting. This is for putting on chamfered shanks.

 

[Best]

If you were ever putting a pipe with olive into a plastic tail, first compress the olive onto the pipe with a brass fitting, making sure the olive is no further on the pipe than the tail depth.
Then wrap some ptfe tape over the olive and nip it up gently and not too tight to the fitting. You only need it to hit hard as the olive is already compressed.
Redring showers tended to have a plastic bend with a brass nut and copper olive and you had to do the above with them. Never any bother if you did it right