Hi Folks,

I want to replace some unused and leaking joints on part of my gravity 
heating system (I'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've noticed that some of the compression fittings are marked 
22mm, and others 3/4 inch. It's mostly copper pipes. I'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't seen for sale.

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

Thanks

Hugh

Hugh wrote:

> Hi Folks,
>
> I want to replace some unused and leaking joints on part of my gravity
> heating system (I'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've noticed that some of the compression
> fittings are marked 22mm, and others 3/4 inch. It's mostly copper
> pipes. I've had problems mixing 22mm and 3/4" before, and wonder what
> is the correct way to handle this.

Get a  3/4 x 22mm coupling
http://www.bes.ltd.uk/nav_graf/frames_cat.htm
scroll down to adaptors - I prefer endfeed

Cheers
Gilbert


>
> 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't seen for sale.
>
> One last question - is there any problem with replacing gate valves
> with lever valves ?
>
> Thanks
>
> Hugh 

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

gilbert wrote:

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


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.

"Hugh"  wrote in message
news:KMxye.4592$bh1.1449@newsfe1-gui.ntli.net...

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

You can buy 3/4'' olives that fit inside 22 mm fittings.  Like these:
http://www.fmshop.co.uk/product.php?cid=86&pid=178&pn=3+4"+Olive+Brass+Compression+Fittings&SKEY=77fc51096cc68652f9c823c4496efb25

They work out cheaper than replacing the whole fitting.  Bent & Queer (B&Q)
have them on their shelf I think.

Thanks BogWallop,

If this is a standard 3/4" olive (it seems to be), I tried one of these 
when replacing bath taps a few weeks ago. I was connecting an existing 
3/4" PEX pipe to a new 22mm bath tap flexible connection. I had assumed 
that the PEX pipe was 22mm when ordering the fittings. The 22mm olive 
supplied with the new fitting was much too big, so I took a 3/4" olive 
from a spare 3/4" fitting I had. It was a better fit, but there was 
still a bit of a leak. Wrapping some PTFE around the olive seemed to fix 
it, but it still worries me a little, given that it is now hidden 
beneath the bath. Hence the questions about what should and shouldn't work.

Cheers

Hugh


BigWallop wrote:

> "Hugh"  wrote in message
> news:KMxye.4592$bh1.1449@newsfe1-gui.ntli.net...
> 
>>gilbert wrote:
>>
>>>gilbert wrote:
>>>Oops!
>>>er, from the main page go
>>>pipe and fittings > capillary
>>>and scroll down
>>>Cheers
>>>Gilbert
>>>
>>>
>>
>>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.
>>
> 
> You can buy 3/4'' olives that fit inside 22 mm fittings.  Like these:
> http://www.fmshop.co.uk/product.php?cid=86&pid=178&pn=3+4"+Olive+Brass+Compression+Fittings&SKEY=77fc51096cc68652f9c823c4496efb25
> 
> They work out cheaper than replacing the whole fitting.  Bent & Queer (B&Q)
> have them on their shelf I think.
> 
> 

"Hugh"  wrote in message
news:MK9ze.944$EG.855@newsfe5-gui.ntli.net...

> Thanks BogWallop,
>
> If this is a standard 3/4" olive (it seems to be), I tried one of these
> when replacing bath taps a few weeks ago. I was connecting an existing
> 3/4" PEX pipe to a new 22mm bath tap flexible connection. I had assumed
> that the PEX pipe was 22mm when ordering the fittings. The 22mm olive
> supplied with the new fitting was much too big, so I took a 3/4" olive
> from a spare 3/4" fitting I had. It was a better fit, but there was
> still a bit of a leak. Wrapping some PTFE around the olive seemed to fix
> it, but it still worries me a little, given that it is now hidden
> beneath the bath. Hence the questions about what should and shouldn't
work.
>
> Cheers
>
> Hugh
>

These olives are designed for copper pipe, so I'm not sure if they'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'' copper pipes are
starting to show some weakness after many, many years of service, but we
don't always replace whole sections of it at a time, so we always keep a
store of these olives at hand.  We've never had any problems so far.

BigWallop wrote:


> These olives are designed for copper pipe, so I'm not sure if they'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'' copper pipes are
> starting to show some weakness after many, many years of service, but we
> don't always replace whole sections of it at a time, so we always keep a
> store of these olives at hand.  We've never had any problems so far.
> 
> 


That'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.