Redoing CH pipes in plastic

[avrkris]

Dear Experts,

I just bought a house. First night in and it was freezing. Turns up that the "modern CH system" (according to previous owner) consists of up to date combi boiler and a chain ! (yes) of radiators connected with 15mm copper pipe. Most rads are connected in series - output of one goes as supply of next and so on ... by the time the water gets to the last bedroom it's just warm.

I can't really afford a big plumbing job at this stage and with a little kid at home I need to get things going myself - DIY all the way.

I did a bit of soldering in my previous house but not really confident to redo the whole installation, plus I really can't spend more than a weekend doing it hence the idea of using plastic pipes. I've read horror stories about pushfit joints going wrong under the floor so here is my question:

Is it realistic/possible to do a single plastic pipe run from the heater into the floorboards, make a bend (90 deg), continue under the floor, get around the airing cupboard area, make another 90 deg turn to get out of the floor and into the manifold. This way I would avoid any joins under the floor. I would do this for all 4 radiators on first floor (about plastic 15mm pipes going to airing cupboard). I've read that the plastic pipe can be bent, but is it practical to do it the way I'm planning?

Any suggestions/ideas welcome.

Thanks
Kris

 

[Axel]

Jesus H Christ! You don't want a single pipe system. You need flow and return pipes to from the boiler T ing off at each rad. The initial artery from the boiler needs to be in 22mm. Plastic is fine if you are any good at stuff but shouldn't be done as a rush job - that's when they fail!

 

[Morris40]

As Axel said, also you can't bend plastic 90 degrees it will collapse

 

[StuC]

As Axel said, also you can't bend plastic 90 degrees it will collapse

Erm, you can if the radius is big enough ... else they'd never get the coils in the bags would they?

 

[1john]

You can get a former to hold the pipe in a swept 90 degree if thats your bag but tbh there are millions upon millions of perfectly functioning pastic fittings everywhere. Buy good quality fittings (do hep still make the grey/gold/blue ones?) and ALWAYS use inserts. I am not a fan of plastic tails coming up from the floor to the rad, I would rather copper as I feel it can take a bit of a sharp knock, I bet a carpet fitter or two has sliced through some plastic pipe in the past.

 

[Morris40]

yeah fair enough i was thinking of a tight 90 bend, if your going to use platic use the Buteline system compression fittings, much better than crappy push fit, and ignore any comments that say push fit is good as i'm sure there will be some to follow my comments

 

[avrkris]

Well,

I wasn't expecting so many answers, it was my first post on the forum. Anyway thanks everyone for suggestions.

Looks like indeed I really need to run a proper supply/return with 22mm branching to 15mm ... Question still stays, would it be ok to do the 15mm runs in single run of plastic pipe, and as some of you suggested its possible.

As per 1john comment it might not look too good to see plastic coming out of floorboards hence I'm warming to the idea of using some kind of connection in the floor. So pushfit or compression fittings? Thinking JG from screfix, are they any good ?

Thanks
Kris

 

[Axel]

I prefer grey PolyPlumb to John Guest - the fact that JG is de-mountable makes me more wary for underfloor use!

Grey polyplumb can be opened up but harder to re-use.

 

[danhiltonplumbingservices]

i would just hep just cause the pipe is move bendy i used speedfit for years but since working with another gas fitter i have started to use hep .

 

[Stevietee]

Watch out using plastic pipe if there is evidence of mice in the house i.e chewed up lagging etc. tails up at least should be copper to protect against hoovers etc. ,hope this helped.

 

[Axel]

I reckon a piece of Polyplumb is far more tolerant of being bashed by a hoover than a piece of copper.

 

[screech]

If using plastic pipe remember to clip it properly. Almost every leak through a ceiling I've seen in the last 2-3 years has been plastic pipe split (and they split big!) through being bent, leaking when fittings are strained due to a bend or fittings coming off. I prefer copper all the way but if you want to use plastic use inserts and clip at regular intervals

 

[5544]

i still like to use copper. might be worth pricing up getting someone in to do a copper fit, compared to using plastic fittings and pipework. I know copper prices are now daft but there might still be movement to pay for labour?