connecting PEX to copper

[elmsoft]

I want to add radiators to an existing system and assume PEX barrier will be the best material for the new pipework. I wondered if I should connect to the copper using a standard compression fitting or just use a PEX straight pushfit connector.
What is normal practice? ( and why?- if anyone can be bothered )

Thanks

 

[Whitespirit66]

Yes, PEX barrier pipe is the correct type to use. As for connecting, you can use either compression or pushfit. Normal practice is probably pushfit, only because people using plastic pipe usually use pushfit connections for speed and convenience.

There is an argument for compression on plastic pipe. You're not at the mercy of grab rings and O rings. Have known occasions where pushfit connectors have suddenly let go, but not aware of compression doing the same.

Just remember to put the correct support inserts in the end of barrier pipe whether you're using pushfit or compression connectors.

 

[seco services]

If under floorboards etc i prefer compression rather than pushfit.

 

[Charnwood]

PEX or Polybutylene (PB) pipe. Polybutylene is a softer pipe and can be easier to use when it comes to handling/manouevring.

 

[elmsoft]

Thanks guys

Compression fitting always struck me as more convincing but wondered if that was just age prejudice against new fangled inventions.
Push fit seems too good to be true!

 

[Dan Robinson]

IF compression is so good, why isn't it allowed on gas under floorboards?

 

[sooey]

IF compression is so good, why isn't it allowed on gas under floorboards?

Neither is pushfit.

 

[Dan Robinson]

Pushfit isn't allowed on gas because of the o-rings and fire rating.


Why are compression fittings not allowed? .

 

[sooey]

They are if you can get at them with a spanner.

 

[Dan Robinson]

ooohhh -


You can't put them anywhere where you need tools to access them.

The reason.... they can leak.

So... by inference, compression fittings shouldn't be used under floors. Grab rings and o-rings are as, or more reliable than compression IMHO.

 

[sooey]

They are if you can get at them with a spanner.

Means..as long as accessible.

 

[sooey]

So... by inference, compression fittings shouldn't be used under floors. Grab rings and o-rings are as, or more reliable than compression IMHO.

That's a matter of opinion, I'd say push fit are more susceptible to strain than compression. You can have a misaligned plastic pipe putting an undue strain on an o ring which will cause it to fail. Use a compression fitting and it doesn't matter what angle the pipe shoots off at, it will hold it.

 

[Dan Robinson]

That's a matter of opinion, I'd say push fit are more susceptible to strain than compression. You can have a misaligned plastic pipe putting an undue strain on an o ring which will cause it to fail. Use a compression fitting and it doesn't matter what angle the pipe shoots off at, it will hold it.

We can argue this one in circles all night, but the fact remains that compression on gas isn't allowed where tools are needed to make access.... On water - I believe - its daft. Afterall... Look at all these MDPE fittings that are rated for burial - push fits .


*edit* Some manufacturers will say that "strain" can enable the grab ring to bite more into the PEX making the joint stronger - to a point of course. Olives can slip off. Have seen it happen.

 

[sooey]

We're always ripping out boxed in 50 and 60 year old compression fittings which haven't leaked (mostly) , so they've stood the test of time.
I've got nothing against push fit....I just don't trust the bstrds.

 

[Dan Robinson]

We're always ripping out boxed in 50 and 60 year old compression fittings which haven't leaked (mostly) , so they've stood the test of time.
I've got nothing against push fit....I just don't trust the bstrds.

And my Gran smoked 40 a day... didn't catch lung cancer though. .


I prefer copper and solder, but if it can't be seen, I don't have as problem with decent quality Pushfit. Tectite Classic is my favourite. Hard to come by though.