• Welcome to PlumbersForums.net - The international free plumbing advice forum. Professional plumbers sharing advice with fellow plumbers and DIY alike. Register for free today! - Checkout the Plumbing Advice forum and then our Plumbing Videos area which still needs populating.

From the United States of America? - Checkout our specific plumbing forum for you:USA Plumbing Forum

Discuss COPPER & PLASTIC TOGETHER OK? in the Central Heating Forum area at PlumbersForums.net



Hi all,

Gutted out a 3 bed semi with a good condition Worcester Greenstar 28i Junior already installed.
Planning to have 12 rads installed in the house (3 of which will be towel rads), with all new piping to each. Based on previous experience in another property with 1 rad not working because of clogged up 10 mm pipes have specified main runs in 22mm copper and then 15mm copper to each rad.

A highly recommended heating engineer who I had round said that he would do the above but for the 3 large rads in the living room and extension he would come down the wall in 10mm plastic as save chasing and easier to dot and dab over.

1)Is there any issue with this copper 15mm down to plastic 10mm? The radiators in question are 2 large 600x1100 type 22’s in the lounge and a 1780x560 double flat panel in extension? I don’t want any issues in the future with poor heat output

Thanks in advance


Staff member
S. Mod
Gas Engineer
10mm copper not plastic is a min ideally 15mm to each rad


Just do the (small amount of) extra work and put 15mm copper in. If it’s thermalite blocks you can easily cut chases with little mess ( I used an old tenon saw, but you could almost do it with a butter knife).


I would stay away from 10mm plastic the ID of the insert causes a restriction, as said previously go all the way in 15mm copper


10mm plastic is barely equal to 8mm Copper internally.

Reply to COPPER & PLASTIC TOGETHER OK? in the Central Heating Forum area at PlumbersForums.net. Plumbing questions, answers, tips and tricks.

New Posts Threads Members

Most Viewed Threads