Confused over compression and push fit.

[Nugget75]

Hi guys,
I’m getting a load of conflicting answers on whether to use push fit (Speedfit) or compression.

I have 2 plastic hot and cold pipes in situ and just want to extend them to a mixer tap.

I was just going to use push fit have some have suggested (with inserts) but I now have people saying, no don’t. Use compression, it’s better.

Which one is actually better please?

Thanks.

 

[Mottie]

Either would do.

 

[Dereekoo]

Since they are used equally throughout the industry its all down to preference, personally I prefer the physical mechanics of compression joints and have never used pushfit except for a temp stop end but then I am not doing it for money so speed is not important. At the end of the day each to their own.

 

[Mottie]

Make sure you use inserts with compression fittings.

 

[Lower]

Make sure you use inserts with compression fittings.

Edit: Didn't notice that the OP was talking about plastic pipes and not copper so ignore my comment.

Personally, i'd rather rely on an olive rather than a rubber o ring as a long term seal.

 

[Nugget75]

Obviously I’m no plumber but surely you’d use both?
The olive for the seal and insert to stiffen the pipe?

 

[Mottie]

Don't you mean with push fit?

Personally, i'd rather rely on an olive rather than a rubber o ring as a long term seal.

No. Definitely use metal inserts with compression joint otherwise you’d just crush the plastic pipe.

 

[Lower]

No. Definitely use metal inserts with compression joint otherwise you’d just crush the plastic pipe.

Sorry, it hadn't sunk in that the OP was talking about plastic pipes.

 

[Madrab]

Definitely use metal inserts with compression joint

Not all inserts are metal (HEP/PP), and not all metal inserts fit all plastic pipe.

As long as there is an insert - plastic or steel - when using a compression fitting on plastic then that'll be fine, as a DIY job using copper olives will also make the job easier. Doesn't need to be too tight, hand tight then a quick nip up.

Which one is actually better please?

Both have their uses and are just as acceptable as each other IMO, it's really down to personal preference.

 

[Ivor Windybottom]

If the plastic's already there and has to be connected to then IMO pushfit is less risky. Use decent lockable fittings, e.g. Speedfit, together with an insert, their double-sealing inserts are even better.

Use specifically made shears to cut the pipe back to a clean new edge, don't use a hacksaw. Ensure the pipe surface is clean and smooth, don't sandpaper or wire wool it.

The EPDM synthetic rubber used in pushfit O-rings is pretty much everlasting. Old natural rubber, e.g. car tyres, does degrade and turn crumbly. Modern synthetic rubber is a different thing altogether. This is why modern car window seals and surrounds do not harden and crack like they used to in the past.

Compression fittings were designed for copper. They squeeze the pipe very hard, enough for the olive to bite into the copper. They'll probably work on plastic, but the insert is going to have to take a lot more force than it was ever designed for.