10mm plastic pipe for boiler

[mo7]

Why is it every plumber you speak to gives you a different view of what the best way of doing something is?

First there was the argument about copper v plastic. Now its 15mm or 10mm plastic.

So I had a guy in today to quote on a new boiler. He was really good and suggested I go for 10mm pipe which means the pipes can be totally hidden behind plasterboard (dot and dab space).

As it happens I am not sure if I am going for plasterboard or hardwall yet. I prefer hardwall in theory.

He says the 10mm system (with a manifold) and plasterboard is the way new houses are built nowadays and its fine. Whilst that may be true - is it the best way? I know that new build hosues don't always have the best rep!

I suspect with the way he has suggested I will get a very smart finish - as opposed to using 15mm and having pipework boxed in.

Quick research suggests that 10mm may not be ideal for large radiators and if it gets clogged up then it could be serious as the internal diameter is only 6mm so less room to play with.

My radiator runs won't be that long. The longest ones will be around 7 or 8 metres I guess.

I may just specify 15mm pipe (in plastic) and live with it.

I am fairly content to have plastic over copper.

Anyone have a strong view on this?

 

[kris]

Always been a 22mm and 15mm man and have always looked at the folks who use microbore as the workers that like an easy life lol

 

[Gray0689]

Most plumbers will always prefer copper we are creatures of habit mostly and aesthetics copper always will look better

But plastic is fine where it is not on show and of course it can be better as it can be run from point A to B without joints
If I use plastic it's really only from manifolds to rads or manifolds to domestic water points

If your plumber is going to use manifolds then better to use proper manifolds and control your heating at maximum efficiency and put of actuators and stats in all rooms control everything
New houses on mainland I have heard its a lot of 10 mm personally I'd go for 15mm not that I'm saying 10mm won't work

 

[EPH]

I've never had to rip out and re pipe anything done in 15mm.

Microbore is only put in for price and speed, not longevity and effectiveness. Have a think which you would prefer

 

[Meady]

I work on a lot of new builds and they can dot and dab over 15mm pipework easy, so I would go for 15mm all day long.

 

[Best]

7 or 8 metres is a massive distance for 10mm pipe & if that is distance from manifold to radiator, then you need to remember it is double that because it has to return.
15mm onto larger pipes or manifolds is all I prefer

 

[mo7]

Yes 15mm sounds better.

I think you are right about it being quick and cheaper - although I thin kthe word you might be looking for is 'efficient' - but that does not always mean the best - or decent standard.

Hvaing said that, I don't think this guy would have recommended it if he didn't have confidence in it.
What benefit does the manifold give? Is that something that 10mm needs or would it benefit every CH system?

 

[oz-plumber]

I stand to be corrected, bit I have always thought that manifolds and 10mm piping to radiators are DIY systems.

Never done one - nor have I ever entertained the thought.
Seen plenty of installations with plenty of problems though.

They do and can work, but there are restrictions to how much heat can bu supplied through a 6mm internal bore pipe.

 

[gbheatingtech]

Basically, if the guy you had in knows what hes about then he would realise that some boilers over a certian kw output to heating require 28mm primary flow and return pipe work.

Personnaly for me id be staying well away from any small bore pipe work, especially plastic. Once it gets clogged with debris or sludge then your going to have to re pipe that rad which would mean your nice walls will be getting ripped out.

All down stairs rads will probably be 'drops' and will require flushing 3 or 4 times to get TDS readings correct. IMO its better to drop down in the corner of a room once, then go under floor and pipe to all rads downstairs, so you only have one drop and flushing the system becomes a bit easier on the installer.

 

[bewsh]

10/8mm pipe is more efficient and cheaper to install, and more efficient to heat as less water content. But, 15mm copper would be my preference! Plastic fittings have a 25 year guarantee on the fittings but do you really want to rip the plaster off the walls in 25 years to replace a leaking joint?

 

[mooey]

Basically, if the guy you had in knows what hes about then he would realise that some boilers over a certian kw output to heating require 28mm primary flow and return pipe work.

Personnaly for me id be staying well away from any small bore pipe work, especially plastic. Once it gets clogged with debris or sludge then your going to have to re pipe that rad which would mean your nice walls will be getting ripped out.

All down stairs rads will probably be 'drops' and will require flushing 3 or 4 times to get TDS readings correct. IMO its better to drop down in the corner of a room once, then go under floor and pipe to all rads downstairs, so you only have one drop and flushing the system becomes a bit easier on the installer.

Not sure what boilers you ve been fitting but every domestic boiler I ve ever fitted from greenstars 42cdi to vallient ecotec alpha boilers nevr come across 28mil primarys.maybe back the day

 

[Gray0689]

You don't do any oil boilers then
And combi boilers don't count as it's the size for hot water demand before heating

 

[Rybo_1]

Do it right first time! Have you thought of maybe chasing in to the wall to conceal 15mm pipework. Although like said before, I have seen 15mm pipework dot and dabbed over

 

[stevetheplumber]

Nothing wrong with 10mm it works, its neat and its cheaper to install. Micro bore got a bad name in the 60s and 70s but materials and working practices have moved on system are or should be running inhibitor at all times and there's usually no open vents to draw in oxygen and dirt

 

[Ray Stafford]

Nothing wrong with 10mm properly installed, and with the right design.

The reason it has a bad name is because its often used as a "builders bodge" with poor installation, and no thought given to the design.

On the other side of the coin, 10mm will be less forgiving of poor maintenance - if the system is not kept clean, the build up of sludge will be felt faster on a 10mm system than on 15/22mm.

 

[Chalked]

Non barrier 10mm hep2o gave 10mm a bad name. The dreaded flakes:32:

Sized up correctly with short runs, it should work well. After all, you wouldn't wire up a lamp in cooker cable? .
still prefer the look of 15mm though.

Love one of the earlier comments, that you can't get 15mm behind plasterboard! Does nothing get chased in anymore? What's that ticking noise behind the plasterboard ? That will be the surface clipped poly tight between the board and block then!:smartass:

 

[Reg Man]

Its all about design. You can only push so much energy down a pipe. the smaller the less. Properly designed system will see you OK. Hence most go for 15mm to each radiator, although 10mm might work sufficiently, depending on distance and demand.

 

[tamz]

15mm saves thinking. Most can't pipe size or even read a pump graph so it will work:wink:

 

[basildog]

Nothing wrong with 10mm it works, its neat and its cheaper to install. Micro bore got a bad name in the 60s and 70s but materials and working practices have moved on system are or should be running inhibitor at all times and there's usually no open vents to draw in oxygen and dirt

Along with all the 15mm buried in the floor screed that still haunts us to this day you mean ?

 

[mo7]

If you fully chase plastic pipe into hardwall will it cause it to crack?

If you use plasterboard should the pipe still be aprtially chased in rather than touching the plasterboard?

 

[AWheating]

10mm is fine for small to med sized rads( like on new build) with a run less than 5m from manifold/ larger pipework.

its all down to buget in the end, your the customer and if you want a certain thing and want to pay for it then thats what you should fit.

 

[cdodds2004]

15mm and 22mm for the win for sure! I use 10mm in places and don't mind plstic aslong as no joints buried etc.

BUT in my own house i fitted full system in 15/22