Fitting a 15mmTRV to an 8mm microbore pipe

[stl]

Hi,

I am replacing a radiator valve with a 15mm TRV one. The only prpblem is that the pipework is 8mm microbore. I have bought a single piece 15mm to 8mm reducer which fits inside the 15mm compression fitting on the TRV nicely and forms a flush fitting where the pipe would enter. The only thing I am not sure on is do I need anything to stop this leaking. There is no room for a 15mm olive, but do i need to use any PTFE or jointing compound instead - i can't really see how it would be leak free otherwise...

Thanks

 

[oilman]

Is there an 8mm olive?

I'd use a jointing compound to avoid a return visit.

 

[mikej2005]

I fitted a load of Drayton TRV4s to 10mm microbore on my system.

The TRV4s are all 15mm, so the 10mm and 8mm versions come with a suitable compression olive for connecting to copper microbore, like the one at the bottom of this photo :

www.godfreys-online.co.uk/imageview.php?image=mistral_twin.jpg

They're designed to be used instead of a conventional olive and when you tighten the nut at the base of the TRV, the compression olive tightens around the pipe - you then get a 'crack' (where it 'gives' a little) and you then tighten it up an exact amount, according to the instructions.

Not sure if the fitting you have is the same, but these are designed to seal around the (copper) microbore pipe without anything additional needed. It's been 8 months and I've not had one leak yet.

 

[experience]

why not use a 8-10mm TRV instead?

 

[stl]

Mike -

Thanks - the fittings at the bottom of the picture is what I have. I assume I need an 8mm (?) brass olive then and put this over the 8mm microbore and then push it all up inside the 15mm fitting.

Anyone seen any 8mm olives for sale anywhere or am i missing something obvious?

I might have been better using a two part internal reducer (with olive) that B&Q stock! - but here me thinking it would be better and cheaper to go to the Plumb Centre!

 

[AlF2008]

Might be more than you need:

http://www.screwfix.com/prods/11240/Plumbing/Compression-Fittings/Olive-Compression-Fitting-8mm

 

[mikej2005]

Might be more than you need:

http://www.screwfix.com/prods/11240...ittings/Olive-Compression-Fitting-8mm[/QUOTE]

That's just a standard 8mm olive - he'll only be able to use that in an 8mm TRV.

 

[mikej2005]

Mike -

Thanks - the fittings at the bottom of the picture is what I have. I assume I need an 8mm (?) brass olive then and put this over the 8mm microbore and then push it all up inside the 15mm fitting.

Anyone seen any 8mm olives for sale anywhere or am i missing something obvious?

As far as I remember, the compression fitting I described is designed to be used instead of a standard olive so no, you shouldn't need a standard olive as well.

I can only comment on the fittings that I had with the TRV4 though - full instructions were included in the pack, by the way.

If you're not sure or confident you'll get the tight seal you're after, then I'd advise swapping the 15mm TRV you have with an 8mm TRV - these are available.

 

[stl]

Thanks - the fitting I have is the same as the brass one at the bottom of the photo, so I assume I don't need a separete olive then and I just insert this into the 15mm compression and tighten the nut! - I think I got confused because the brass fitting was big and it didn;t look like it would compress much to make a good seal!

 

[mikej2005]

If you've got no instructions, then just take care and don't tighten anything fully until you're happy everything looks OK.

The TRV nut goes over the pipe, followed by the special compression olive fitting, which should sit on the top. Push the whole lot up inside the TRV and tighten the nut. It's probably quite important to tighten the nut correctly. Too much and you risk crushing the pipe - too little and you risk it leaking (the latter being much easier to correct, of course !)

 

[stl]

Thanks - most helpful!

 

[MANDATE]

B & Q do have 8mm olives, I don't know if they are brass or copper.
I prefer copper, softer than brass!
You could also try Focus Do It All.

 

[petit_pablo]

Make sure when you tighten up to these adapter olives that you hear the audible click. (It does sound a little like you have snapped something!)

BG use these olive adapters as they dont want to spend out on different sizes of rad valve

 

[nickso]

Make sure when you tighten up to these adapter olives that you hear the audible click. (It does sound a little like you have snapped something!)

BG use these olive adapters as they dont want to spend out on different sizes of rad valve

and they work, but if you want to use something more reliable use the two piece versions.