What's the last resort?

[jlacd]

I'm fitting a cistern just now, and I simply cannot get the ******* union to be watertight. Cisten bottom-fill is a plastic 1/2" male thread, and I'm screwing on a 90 deg. female 1/2" elbow. Plastic is definately not cross-threaded.

Do I just wind on more and more ptfe? How many turns is "too much"?

Or is there a well-known "last resort" eg - slather the thread in silicone sealant before screwing up the union? (or will I screw it up properly doing that )

Cheers

 

[gas4you]

You should be using a 1/2" fibre washer in connector to ball valve connection

 

[jlacd]

Oh, the little red thing that's all chewed up when I disconnect it? I've gone through a couple of them already.

 

[EliteHeat]

Oh, the little red thing that's all chewed up when I disconnect it? I've gone through a couple of them already.

Don't do it up so tight then

 

[jlacd]

It leaks if I don't.... so I need more tape?

 

[Paul Barker]

The fibre washers were designed for machined brass and copper unions. These modern molded plastic float valves are not machined to an adequate standard and not of adequate material for the old tecnique to work reliably.

The grey Hep20 tap connector has a cone shaped rubber interface that seals good, or use a flexi with a rubber seal in it.

The plastic may now be split necessitating a new float valve and starting again.

 

[jlacd]

Sorted.... found the brass elbow from <insert name of major online retailer here> had a thread all rough and burred. Tickled it up with a jeweller's file, and all's well. I guess it was rough enough to cut up the ptfe to the point of uselessness.

Magic - the pan works - I'm off for a dump.