Burst plastic piping.

[ShaunCorbs]

Ok, thanks.

Any ideas where my problem lies?

no sorry my best answer is to send a section that burst to the manufacture

 

[Ric2013]

Hmm. There are various PRVs on your system. I'm not familiar enough with this type of system to work out which one serves the section of pipe that is failing. At 60°C, 9 Bar is the limit, 7 Bar at 80°C, and I note one of those PRVs doesn't kick in until 9 Bar. And I'm suspecting one or more of those PRVs may not be working 100% correctly. Anyone think there is any mileage in this train of thought?

 

[zzzjim]

The flexi on the expansion vessel , made me think of a boiler prone to blockage in flexis ... Not good on unvented !

Was the split facing the same way as last one -below ?
(seam fault /or scratched during instal ..! )

 

[Best]

I have seen that happening to plastic pipes on flow from oil boilers where the oil boiler was overheating.
Yours is happening always on flow pipe, which points to overheat.
The barrier pipe has 2 walls and breaks down (basically melts) when overheated, goes paper thin and splits.
I don't know if it is possible a gas boiler could also overheat, but I guess it could.
Is the heat in the pipes from the gas boiler extremely hot?
The red expansion vessel (EV) is for your heating system and should be connected where it cannot be isolated from gas boiler. The vessel needs serviced each year to check it has correct air charge, but the PRV on it is supposed to keep heating system limit to 3 bar max should the EV fail. If it was a over pressure problem that would mean both the PRV and the red vessel are faulty. Personally I would also have a PRV off pipework close to boiler as good practice.
Even if your PRV and red vessel were non functioning, it normally wouldn't cause your heating system to run with extreme pressure, but I would check the filling loop isn't passing mains water through into system and raising it to very high pressure.
The hot water unvented unit and its valves are irrelevant if it is definitely a heating system flow pipe bursting, as they are to do with mains hot water - the red vessel with its PRV, filling loop and gauge are the heating parts to have checked.

 

[king of pipes]

I would employ the services of a G3 engineer and replace all the saftey valves and both expansion vessels on the system it is looking a little tired and could do with some tlc, the expansion vessel on the cylinder needs supporting better than it is when they fail they weigh quite alot, i have had over heating on the hotwater side of these cyliders the thermostat pocket is quite large which the stat bulb slides into which allows the water temp to creep higher than it possibly should it needs to be measured and checked , set your boiler stat to 650c no higher and check this also . cheers kop

 

[Bogart]

I had an experience of a Hep2O bursting in my place due to the boiler overheating. As the temperature rises the pressure it can stand drastically reduces. At above 80 odd degrees C the pressure it can withstand is less than 3 bar hence the pipe bursts before the prv operates.

 

[Ric2013]

3 bar at 80°C? Not according to the data I've looked at! Does Hep come in various types?

 

[king of pipes]

Heres what i have found

 

[Bogart]

Definitely looks like they have improved things since my burst, which was over 15 years ago.

 

[Dkdc71]

Looking at your photos if you have repaired the pipework you have no water in the system your 3 bar safety valve should be on flow from boiler as one of the posters has said it looks like overheating so it looks like steam you ate creating and bursting the pipework at the same point constantly what temp is your boiler at ?