10mm or 15mm speed fit pipe for Kitchen Radiator

[Dougie212]

Hi there

So im fitting a radiator in our kitchen.... the coldest room in our house and has never had one fitted until now. The boiler is above the wall the radiator is going and currently the ceiling is down, so I have clear sight and access to the two 22mm pipes for the central heating. Everything I have done in the house so far, I've used 15mm copper and recently been introduced to plastic and find it much easier and quicker to work with, so I was intending on running plastic pipe to the new radiator, but I have had a couple of questions put into my head that I could do with clarifying please :

1) From the 22mm pipe work should I really be using 15mm pipe to come down to the radiator? this was my intention until someone told me that 10mm would be sufficient and would be easier to manoeuvre when exiting the wall and running along to the radiator valves. I intend to fit a 600x600 single panel radiator....

2) My pipework will run down the wall then turn left towards the radiator. Im thinking that the pipes would be better coming out of the wall downward facing so as to bend off left and right to the valves. Again, someones told me "nah.... you'll be right... just bring the pipework across the wall and use angles"... (the plasterboards off in the area at the min too so everything is easy to run). So basically.... am i right in my though of coming down the wall, turning left then turning down the wall again down the centre of the radiator to pop out of the plasterboard (when fitted) to turn off to the valves.

Thanks as always in advance!!

Dougie

 

[Madrab]

Yes, 10mm will feed a rad of that size no bother, especially if it's off the main 22mm flow and return.

If you are doing drops you may want to think about a drain on that rad supply too.

Most if not all professional trades run everything in relatively straight lines. I'd avoid angles where ever possible

 

[Dougie212]

brilliant.. thanks Madrab.
I'll try and get a picture of the wall I'm fitting it to which will hopefully explain why I think I need to turn... although... will 10mm just turn..?? I'll get a pic...

 

[Dougie212]

I'll never be Bill Gates, but Ive taken a pic and put some lines on and things to show the positioning.. The only thing I seem to be encountering is 10mm plastic pipe doesn't seem so readily available in 2/3 mtr lengths, just long coils which is excessive for my needs.

 

[dilalio]

I take it that your boiler is a combi?

 

[aptsys]

Just do it in 15mm copper. It's a simple run and you won't need to worry about the plastic fittings leaking in 10 years time from being so close to the boiler.

 

[Dougie212]

It is a combi boiler dilalio, yes.

Aptsys, is it the pressure from being so close to the boiler that will cause the joints to leak??

 

[durhamplumber]

It is a combi boiler dilalio, yes.

Aptsys, is it the pressure from being so close to the boiler that will cause the joints to leak??

The pressure is the same throughout a sealed system..A plastic joint is no more liable to leak being near the boiler.(They should not be used within a metre of boiler)

 

[John D v2.0]

It is a combi boiler dilalio, yes.

Aptsys, is it the pressure from being so close to the boiler that will cause the joints to leak??

With plastic make sure you get barrier pipe rather than non barrier for heating.
Plastic is more likely to fail catastrophically whereas copper would be more likely to simply leak.
10mm pipe isn't much different price than 15mm in plastic but it's much easier to run and would be enough.
The pressure would be highest by a small amount just after the pump but plastic pipe is rated to 3 bar plus anyway. Just don't use any fittings that say hot+cold water only.
The biggest benefit to plastic is it's about as hard as doing Lego, and you can just lift the rads off the wall to paint or drain the radiator even with the pipes hidden.
The disadvantage is you wouldn't want to have it on show anywhere!

 

[Dougie212]

Thanks John..! I was hoping to use 10mm but I only need just over 7 metres of it and typically I can’t find it in anything shorter than 25m coils, unlike the 15mm which I can get in 2 & 3m lengths.

 

[Madrab]

Now I've seen the length of the run, it would be just as easy doing it in 15mm as it would 10mm,it's not as 'flexi' as the 10mm may be but just as easy IMO

 

[Dougie212]

Cool.. and... I’ve got a bit of 15 from the last project left so it’ll come in handy..

 

[Dougie212]

Just out of interest.... would having a double panel 600x600 affect any of the pipe sizings ive mentioned??

 

[John D v2.0]

Just out of interest.... would having a double panel 600x600 affect any of the pipe sizings ive mentioned??

No for 7m total length even with a 11c temperature drop it would be ok. You do have to watch both water velocity and head loss though but you can calculate to be sure. I did a 12m total length no problem on a similar rad although I'm designing for a 20c drop in my system.
I forgot the limits off hand but i could get 1.8kw

 

[aptsys]

The pressure is the same throughout a sealed system..A plastic joint is no more liable to leak being near the boiler.(They should not be used within a metre of boiler)

I read it as the boiler is just above on the same wall.