Plastic pipes on sealed central heating system.

[duvet77]

I'm about to embark on my first plumbing project; replacing a radiator and associated pipe work to the lounge. I've read some of the previous posts and i'm pretty sure I know what I'm doing but would like a few things confirming:

Is plastic pipe acceptable on a sealed central heating system, as long as pipe is barrier pipe?

Is inhibitor ok to use in systems with plastics pipes?

Are all pushfit fittings and pipe compatible? i.e. don't have to be same brand pipe and fitting.

Can I use plastic pushfit isolation valves on my existing copper pipes to connect the new plastics pipes. The existing isolation valves are leaking so i want to change them.

I reckon the answer to all them is yes but I'd like someone more knowledgable than myself to confirm!

 

[HarrogateGas]

Yes indeed to all of them. However i'd be tempted to use the same brand fittings as the pipework. They do all fit and seal however the manufacturers will not say they can be used with another brand product so best do things by the book.

 

[duvet77]

Thanks.
Any advice on brands?
Wickes do Speedfit and Polyplumb, Screwfix do Speedfit and FloPlast.

 

[HarrogateGas]

Speedfit are ok but my fav is Hep20, for a DIYER the fittings and components are the most easy to use and IMO the neatest too.

 

[Whitespirit66]

Whatever you do, don't forget to buy some pipe inserts to go in the the ends of the plastic pipes, before they are inserted in to the fittings. They are small, but vital components that are occasionally overlooked by some DIYers.

Good luck.

 

[duvet77]

Thanks guys.
I won't forget the inserts!

 

[namsag]

Also read boiler manufacturers instructions as there is the odd one or two out there that says no plastic at all when on a sealed system

 

[ChrisR]

Go for it.
This never happens.

Almost

 

[duvet77]

what happened there then?

 

[BigBurner]

what happened there then?

The hotter it gets the less pressure it can take. If it get way too hot with excessive pressure and the pressure relief does not open when it should, that can happen. Also some pipe may get scored on the surface when fed through floors/walls, etc. This weakens the pipe and that can occur at quite low temperatures/pressures

 

[HarrogateGas]

what happened there then?

The hotter it gets the less pressure it can take. If it get way too hot with excessive pressure and the pressure relief does not open when it should, that can happen. Also some pipe may get scored on the surface when fed through floors/walls, etc. This weakens the pipe and that can occur at quite low temperatures/pressures

Also a nuclear bomb may go off in the loft and the plastic pipe will be sure to leak first..........

Ignore the scaremongers, it really is a brilliant product if used properly. Its opened up basic plumbing to even the novice of DIYers

 

[HarrogateGas]

Go for it.
This never happens.

Almost

Cant see the end of an insert there............cant really blame the pipe for poor workmanship!

 

[duvet77]

Also a nuclear bomb may go off in the loft and the plastic pipe will be sure to leak first..........

that did happen to me once but luckily the christmas decorations softened the blast.

 

[namsag]

Harrogate how would an insert stop a pipe splitting outwars as this one has done. If it was so safe and an excellent product why would some boiler manufacturers say do NOT fit on sealed system ,i have never seen any boiler manufacturer say do not use copper

 

[Corgigrouch]

Unfortunately from that picture, we cannot tell what has caused that pipe to burst like that.. It is designed to work within set parameters of temperature and pressure.. If the boiler overheat had been bypassed, PRV been tampered with or just not fitted, then this could happen. But is it really the fault of the pipe?..... Of course it may have been where it could have been exposed to the elements and frozen...

I like to think that plastic would melt if my house was on fire and put the fire out.. Lets see copper do that

It is funny that plastic components are used so widely in todays world in situations that would make people cringe if they thought about it, yet pass a bit of water down a quite substantial plastic pipe and it is a truly terrible thing. We heating guys are a very conservative bunch aren't we?