3/4" <-> 22mm conversions

[Hugh]

Hi Folks,

I want to replace some unused and leaking joints on part of my gravity heating system (I&#39;ll be draining it first). I will probably also replace some of the gate valves when I am at it, as several of these are already faulty. I&#39;ve noticed that some of the compression fittings are marked

22mm, and others 3/4 inch. It&#39;s mostly copper pipes. I&#39;ve had problems mixing 22mm and 3/4" before, and wonder what is the correct way to handle this.

Can 3/4" olives be used with a 3/4" pipe in a 22mm fitting ?

Can a 22mm olive be used with a 22mm pipe in a 3/4" fitting ?

or do I need special conversion olives, which I have heard about but haven&#39;t seen for sale.

One last question - is there any problem with replacing gate valves with lever valves ?

Thanks

Hugh

[gilbert]

Get a 3/4 x 22mm coupling

down to adaptors - I prefer endfeed

Cheers Gilbert

[gilbert]

gilbert wrote: Oops! er, from the main page go pipe and fittings > capillary and scroll down Cheers Gilbert

[Hugh]

Thanks Gilbert. I was hoping to reuse some of the compression fittings. But looking at the price of the 3/4" x 22mm compression couplers on that site it would probably be cheaper to change all the pipes to 22mm.

[BigWallop]

These olives are designed for copper pipe, so I&#39;m not sure if they&#39;d be right for plastics. On copper they are perfectly fine. I use them a lot on the older building we keep maintained. The old 3/4&#39;&#39; copper pipes are starting to show some weakness after many, many years of service, but we don&#39;t always replace whole sections of it at a time, so we always keep a store of these olives at hand. We&#39;ve never had any problems so far.

[Hugh]

That&#39;s good to know - most of my pipes are copper anyway. I have also read that there is a difference between plastic and copper imperial pipes - where 3/4" copper pipes were measured by the internal diameter and 3/4" plastic by the outer diameter. It seems strange, but might explain the problem I had.

Thanks for your help.