Which pipe is the best

[f49h]

Hi Guys and Gals.
I am going to upgrade my central heating system to a combi boiler.
I hav 8mm pipe to the radiator. I want a complete pipe re run.
Would 8mm be OK or will I have to go bigger.
Any views on plastic??
If I fit 15 mm pipe is compression fittings ok or solder.
Money the deciding factor.
Cheers

 

[Prof.plumb]

Obviously when running any pipe from the boiler you must for the first meter run them in copper. I usually run 22mm flow and returns across the landing and tee off to rads in 15mm. Never go under 15mm it causes no end of problems. If money is a problem don't use plastic. It is expensive and i believe un reliable (especially under 2 bar pressure that combis run at) plastic fittings rely upon an o ring seal and expand and contract daily and eventually that o ring has to perish which will cause leaks. I believe in ten years time we will all be going in and ripping plastic out. Copper has stood the test of time it is brilliant. Use soldered fittings where possible they are neat, cheap and reliable.

 

[weareleeds]

Ditto & make sure that when you have finished syste piping do a cold flush then add a cleanser switch boiler on to get all rads hot flush that out get system hot again flush that out then fill system & add inhibitor (especially if using modern flux)

 

[f49h]

Thanks guys,
I've decided to run the pipework myself.
Can you get a 15mm manifold to run the pipework to the radiators or is it advisable to run the 22m inlet and return rail so i can T off for each radiator.
Also what is better compression or solder joints.
Cheers

 

[Softus]

If money is a problem don't use plastic. It is expensive and i believe un reliable

Is the guess that it appears to be, or do you have evidence that plastic is "unreliable"?

Do you know the relative wear rates of plastic and copper tubing? Will copper corrode before plastic wears out? And what is the effect of contraction and expansion on soldered joints?

I believe in ten years time we will all be going in and ripping plastic out.

Why would we do that, when plastic is guaranteed for 50 years?

Copper has stood the test of time it is brilliant.

Has it? Is it? Have you ever gone into a house and replaced a corroded section of copper tube, and found that when you cut into it the walls are so thin that the tube folds? How often does the same thing happen with plastic?

In underfloor heating, do you know whether plastic is used, or copper?

Use soldered fittings where possible they are neat, cheap and reliable.

Would you solder under a floor, risking a naked flame near combustible materials?

Do you actually have any scientific basis for the things you claim to be fact?

 

[chrishutt]

Never go under 15mm it causes no end of problems.

Millions of radiators are fed by microbore tubes of 8mm and 10mm and work perfectly satisfactorily. I've been installing microbore for 25 years and have never had a problem. Only the incompetent need fear microbore.