Corrosion problem in central heating system with standard plastic piping?

[Dr Doolittle]

air will penetrate cells, with water it won’t

what is water made from? Hydrogen and oxygen. Can you see how silly your argument just became?

 

[ShaunCorbs]

what is water made from? Hydrogen and oxygen. Can you see how silly your argument just became?

it’s true so not silly its why they installed the plastic barrier layer as they found it out and why when you find a non barrier heating system installed its slugged up and normally needs a repipe

Standard Plastic Pipe non barrier allows a very small amount of oxygen (not air) to enter the system

Also this is why mlcp is 100% air and water tight non permeable due to the alu layer

 

[Dr Doolittle]

it’s true so not silly its why they installed the plastic barrier layer as they found it out and why when you find a non barrier heating system installed its slugged up and normally needs a repipe

Standard Plastic Pipe non barrier allows a very small amount of oxygen (not air) to enter the system

Also this is why mlcp is 100% air and water tight non permeable due to the alu layer

I can't comment further as I think that you actually believe this so its no longer a joke

 

[ShaunCorbs]

I can't comment further as I think that you actually believe this so its no longer a joke

explain your theory then

 

[Dr Doolittle]

explain your theory then

I don't have any theories about how oxygen atoms pass specifically through plastic heating pipe but nitrogen/hydrogen etc don't.

 

[Ben-gee]

Unlikely to be many oxygen atoms about as it exists as molecules, not atoms.

 

[John.g]

It must gain access one way or the other otherwise plastic pipe makers would hardly spend lots of money developing a barrier type.
As I've said previously though I'm a bit surprised that system pressure don't rise with this and why systems require top up after venting air, assuming no system losses.

 

[Dr Doolittle]

Unlikely to be many oxygen atoms about as it exists as molecules, not atoms.

LOL

 

[Dr Doolittle]

It must gain access one way or the other otherwise plastic pipe makers would hardly spend lots of money developing a barrier type.
As I've said previously though I'm a bit surprised that system pressure don't rise with this and why systems require top up after venting air, assuming no system losses.

how about I suggest that the air is already in the pipe rather than being sucked in.

 

[EvilDrPorkChop]

It must gain access one way or the other otherwise plastic pipe makers would hardly spend lots of money developing a barrier type.
As I've said previously though I'm a bit surprised that system pressure don't rise with this and why systems require top up after venting air, assuming no system losses.

What I usually find is that the system doesn't loose pressure, more than it gains Air instead. I don't know the ins and outs but it must be reacting with something in the Air gained with the water in the system to replace the water with Air instead?

For instance the Radiators fill up with air, but the pressure will maintain at 1.5bar if there's no automatic air vent. If there is then the pressure drops, as the air is let out and you need to refill the system.

There's an estate that I work on where the cheaper houses were OV and the more expensive ones got Sealed systems with Unvented cylinders. The developer 20 years ago used Speedfit fittings with Non Barrier Polypipe pipe. It's the Sealed systems that i've had issues with, not the OV ones so far. Many have had the original OV systems taken out and had Combis in so it'll be interesting to see what happens long term.

It's a problem i've really only myself come across in the last couple of years, and the sweet spot seems to be systems that are between 15 & 20 years old.