Connecting to some 7/8" pipe

[HiZ]

what is the best way to connect to a old 7/8" pipe so I can run a new 15mm copper to the bath/sink (combi fitted soon)?

I guess i need a 22->15mm reducer but does a 22mm compression or copper push on fitting mate with 3/4" OK.

Is 7/8" just the same as the newer 22mm and will it fit ok?

EDIT: Stated 3/4" but i measured again and i mean 7/8"!

 

[ChrisR]

Push fit - there is a 3/4 to 22 adapter in some makes
Compression - use the 3/4" olive
Solder - use 3/4 to 22 adapters, solder ring or endfeed.

 

[HiZ]

I mean 7/8" doh....

 

[JohnD]

Is this an old copper pipe? If you measure its internal diameter you will probably find three-quarters of an inch, then its old three-quarters which marries (using a different olive) to modern 22mm.

Modern pipe is measured by external diameter.

old half-inch i.d. copper matches 15mm o.d. copper using the same olive.

If it is iron pipe it will be more difficult.

 

[chrishutt]

¾" copper pipe has an OD of 21.5mm. This is close to 7/8" (actually 27/32"), so presumably what you have.

 

[HiZ]

Do plumbers merchants stock 3/4" olives or are they like rocking horse sh*t?

 

[Agile]

Most better merchants have a blister pack of about three or four 3/4" olives at a price of about £2.

They usually will form a seal in a 22 mm fitting but that is one of the few cases where I would agree that a few turns of PTFE tape over the olive will be a good idea.

Tony

 

[bster]

Agile wrote

one of the few cases where I would agree that a few turns of PTFE tape over the olive will be a good idea.

I've been told to ptfe every olive or boss white it (depending on wheather it is potable or not).

are you saying that its not a good idea to PTFE olives in your opinion?

 

[croydoncorgi]

From the IBP-Conex website:

The Conex compression joint makes a metal x metal seal which normally
eliminates the need for jointing compounds and sealants. On larger
sizes, particularly 54mm, it may be necessary to use an additional
WRAS approved sealant. Jointing instructions, when using sealant, are
available from our Technical Department.'

Since presumably the manufacturer knows how to use its own product, why do we (continually!) need to second guess and improve on their advice?

see http://www.ibpgroup.com/english/conexjointing.htm

What's the PTFE tape supposed to achieve? (If you respond,make a better answer than 'stopping the thing leaking'!) IMHO, it can't add any value at all. Liquid sealants are a different issue - refer again to IBP advice regarding 54mm and larger sizes.

 

[Nige F]

Do plumbers merchants stock 3/4" olives or are they like rocking horse sh*t?

They look like a rocking horse` anus

 

[Softus]

What's the PTFE tape supposed to achieve?

It actually acts as a malleable seal that counteracts any imperfections in the metal sealing faces. Applied correctly, there's no harm in using it.

The always/never PTFE argument is very similar to the copper/plastic argument - generally, on the one side, there are people who believe that one material or method is the best for all circumstances, and, on the other side, people who are prepared to think on the job and choose the material and fittings that offer the best compromise of speed, reliability, cost and looks.