New radiator and end pipes. Copper 10mm to plastic 10/15mm

[gambo]

I'm replacing a few radiators and some of them will be in a different size, so I may need to change the pipes as well. At the moment the pipes are 10mm copper. Given it's not a straight line to TRV I'm thinking about using JG PB pipe.

There are couple things that worry me:

- the plastic pipe has a rating of around 3 bars for >90 degrees. I know it's still more than what the system is used but it's not way more (comparing to copper).

- the plastic pipe has inner diameter same as copper but the outer is slightly bigger due to multilayers. Will it cause any issues when connecting to TRV?

- TRVs are 15mm, copper 10mm so I need to use a reducer. Does it make a difference if i connect 15mm plastic to 10mm copper for the last 20-50cm rather than reducing at the trv point?

- the plastic pipe requires insert at the joining point so the 10mm pipe is reduced to 6-8mm? Does this cause any issues?

 

The other thing is that I'm willing to do it to avoid draining the system and soldering. So, ideally i would use compression fitting to connect plastic with copper and then straight to trv. But if I'm using the compression fitting then could I not just use copper on both ends with compression fitting instead of plastic?

 

Edited February 11, 2023 by gambo

[gambo]

Seems like I can't make further edits. I've watched YT and found pipelife easy-lay pipes which have quite good rating (7bars for 80degree).

[Nickfromwales]

47 minutes ago, gambo said:

So, ideally i would use compression fitting to connect plastic with copper and then straight to trv. But if I'm using the compression fitting then could I not just use copper on both ends with compression fitting instead of plastic?

Do not use compression on the 10mm ( or any other size ) pushfit pipe, please! Use pushfit ( Hep2o ) with copper and you'll be 100 times better off.

 

If you use 15mm radiator valves you can get 15x10mm pushfit connectors :-

 

https://www.monsterplumb.co.uk/pushfit-chrome-elbow-10mm-15mm-stem-radiator-valve-pipe-heating?gclid=CjwKCAiAlp2fBhBPEiwA2Q10DzsSfFBBScywMdc98a47iV3CqwoxWnFENIEt_ZvaBI69IiKogpAeHBoCn7YQAvD_BwE

 

Would these help?

[Nickfromwales]

You can also get 10mm radiator valves. I assume you know this?

[Nickfromwales]

Also, you can buy a 10mm copper pipe bender, and this will allow you to do away with the bends. It's an absolute doddle to use too, you'll pick it up in no time at all.

https://www.eurocarparts.com/p/amtech-3in1-pipe-bender-553991790?gclid=CjwKCAiAlp2fBhBPEiwA2Q10D9i5um8j5E9TqrmcWgIarsbkqiM9B_qHmywt3TTJkgn2Jj8a9FAR0xoCxHkQAvD_BwE

 

Just practice on a couple of bits, and ask questions here for tips on using it.

[gambo]

Why is compression fitting such a bad thing? the same principle is used at the connection with TRV

[HughF]

On 11/02/2023 at 23:33, gambo said:

Why is compression fitting such a bad thing? the same principle is used at the connection with TRV

I’ve never had an issue with compression onto plastic, using the correct inserts. I’ve also never had an issue with compression onto mlcp using euro ones.

 

Nick has had lots of issues with them coming undone or blowing off, hence his recommendation to not use this method.

 

YMMV….