Polypipe fitting failed after 1.5/2years

[CAESAR32]

That had happened was 100percent screwed on right when left the job 2 years ago.

 

[CAESAR32]

The fitting is touching the joist could the heating and cooling over time or caused the fitting to unscrew?

 

[BlueLoo]

The fitting is touching the joist could the heating and cooling over time or caused the fitting to unscrew?

There is a copper insert.

Dunno if this is relevant here but micro strains between different materials in a pipe junction can cause havoc over time.
Plastic expands at a greater rate than copper.
If the plastic has expanded faster than the copper then the junction looses its tightness. In this configuration, perhaps it waa loose enough to undo over time as the fitting rails up and down the beam during cycling.

Maybe.

 

[HERTS P&D]

Not correctly inserted into fitting.

Or tight enough.

Andy

 

[CAESAR32]

So it could be the use of copper that was the issue. Have used copper before with poly with no problems.

 

[HERTS P&D]

Or it could of being the Plumber not doing his job correctly.

Andy

 

[CAESAR32]

Or it could of being the Plumber not doing his job correctly.

Andy

I.e not tightened the fitting?

 

[HERTS P&D]

Yep.

Andy

 

[Notch7]

Actually not! some years ago we had a 15mm grey poly elbow fail after around 3 months.
Open vented system elbow failed over night large amount of decoration damage to ground floor plus carpets.
When you looked at fitting in effect 3 of the grab ring teeth were missing.
All costs (including ours) paid by polpipes insurers.

it mustve been had cutting off those 3 teeth

 

[Notch7]

It wasn't tested to 18 bar I know poly say to do this I do on new builds but on domestic central heating install It hasnt been.

18bar is pretty high

 

[CAESAR32]

That's what poly specific on there technical instructions.

 

[CAESAR32]

There is a copper insert.

Dunno if this is relevant here but micro strains between different materials in a pipe junction can cause havoc over time.
Plastic expands at a greater rate than copper.
If the plastic has expanded faster than the copper then the junction looses its tightness. In this configuration, perhaps it waa loose enough to undo over time as the fitting rails up and down the beam during cycling.

Maybe.

If that was the case surely they should say not to use copper and poly together on a tee section. Was done to save fittings on the pipe leaving to the rad. It's 15mm copper bent straight up to the rad. Valve. As appose to 15mm poly, poly elbow and copper to rad valve.

 

[BlueLoo]

If that was the case surely they should say not to use copper and poly together on a tee section. Was done to save fittings on the pipe leaving to the rad. It's 15mm copper bent straight up to the rad. Valve. As appose to 15mm poly, poly elbow and copper to rad valve.

Never used any of this (not a pro plumber) so this is just observation.

One thing to note as well is the configuration and stiffness of the various branches. There is a lot going on at this juncture. The copper pipe is much stiffer than the poly and crucially, this stiffness appears to be in the worst branch as its resisting the movement and flexure of the poly.

Could well be a install issue but there is enough going on here to not do something like this again.

Copper on the branch. Ok. But on one half of the header? Hmm.

 

[SandyLyon]

18bar is pretty high

The “original” Hep2o is the same, both a low pressure test and a further test up to 18 bar.

This is because both Polyplumb and the “original” Hep2o fittings are “O” ring first, this basically means that when the pipe is inserted into the fitting it passes through the “O” ring first then the grab ring second.
If the pipe isn’t inserted fully it could pass through the “O” ring, sealing at low pressure without biting on the grab ring and could possibly “blowout” at a higher pressure, hence the 18 bar test.

The “Grab Ring” first fittings, Hep2o, Polymax etc, generally only require a pressure test of 1.5 times the maximum working pressure.