Oxygen Barrier Pipe

Rod Kotiga

Oh ya. Change that too. Good point. We use the potable ones anyway.

Rod

Arthur

Oxygen Barrier.

Can anyone point in the right direction over oxygen barrier requirements, Another tradesman claims he uses ordinary plastic pipe in the underfloor piping and to advoid oxygen infillation he 'pressurises the pipe.
I always understood the water pressure was imaterial as the oxygen gets in regardless of water pressure.
Can anyone point me to some definitive studies on this.

Glenn Sossin_2

Oxygen Barrier

Oxygen is a gas that can pass through the wall of the pex. I believe it relates to a concept called partial pressures. The concentration of a gas will try to equalize on both sides of a barrier - in this case the pex.

As the oxygen in the boiler fill water starts to latch on to iron and create rust, the concentration of free oxygen in the boiler water starts to decrease. Now there is more free oxygen on the outside of the pex than on the inside.

The oxygen tries to equalize itself and passes through the pex wall, into the boiler water so the concentration of molecules is the same on both sides. Again, in the boiler water, the free oxygen molecules latch on to iron - creating rust, and the concentration of molecules on the inside of the pex drops .... and again, free oxygen in the air, passes through the pex wall in an attempt to equalize concentrations on both sides.

This process theoretically will continue as long as there is a different concentration of oxygen molecules on either side of the pex wall. This concept is very familiar to any certified scuba diver as the concentrations of molecules in a gas change under pressure.

Pressurizing the water in the pipe won't change or reduce the oxygen concentrations. In fact, it would theoretically increase the temperature of the water, slightly increasing the speed of chemical reactions like rust.

Even buried under concrete this process continues over time. Concrete is porous so the gasses pass through. The aluminum pex is immune from this because the oxygen can't pass through the aluminum sheathing.

Your plumber friend is dead wrong. Have him look inside an iron circulator in one his systems after a couple of years (see photo attached. Using no barrier pex only accelerates this process. Think of it as wet talcum powder that starts to cake up. It can form a very fine silt which can harden and prevent check valves from seating properly and other product failures.

I think I've got this right. Hope this explained it clearly.

My $.02
Glenn

bill_97

Are there any

chemicals or additives that can be used on a boiler that has non oxy barrier pex connected to it ?

We were on a water heater replacement a few weeks back and the boiler had 1/2 inch non barrier tubing going to an upstairs baseboard zone . I told the homeowner about the problem and said there's no cheap fix , but as a longshot I'd ask about chemicals .

BTW , I was in Lowes the other day and saw they stock pex now . I asked the plumbing aisle guy if they had oxygen barrier tubing for closed loop systems . He looked at me like I was an idiot . So I can see this being a pretty big problem down the road .

Rod Kotiga

I only use pex with an 02 barrier. But if your in a situation where the pipes are installed and there is no inexpensive way to change them out then there's no reason to panic. First get rid of your fresh cold water make up line and install a glycol feed tank ( axiom pro pal 2 ) and fill the 6 gallon tank with 60% water 40% Rhomar inhibited glycol. Also purge your system with the same mix. We've come across the corrosion of pumps and other steel or cast iron parts alot and have found that a good mix with a glycol that has corrosion inhibitors in it and that is checked annually for ph will solve the problems. Also the cast iron pumps look like new inside years later. You can get anal if you want and mix with distilled water too.

Rod

Drew_2

Propylene Glycol

Rod, Why would you want to put propylene glycol in a system that isn't in need of freeze protection?

Rod Kotiga

Corrosion inhibiters. And because that's what we found works.

Rod

Glenn E Sossin_2

Change to Bronze Pumps

To increase the functioning time of your system, you could use bronze pumps instead of iron pumps - affected less by oxygen in the water. You could also change from iron flow checks to zone valves or Bronze checks. Lastly, you could use a plate exchanger with a bronze circulator to isolate the pex loops side from the rest of your heating system.

Of course all of this could be somewhat costly so I'd look at these costs and the amount of time you plan to stay in your home.

Good luck

My $.02
Glenn

Arthur

Oxygen Barrier

This is not actually my problem just that another tradesman tells me he using ordinary plumbing pipe with no barrier and I've alway used barrier, Funny enough the pipe he uses is more expensive than the pipe I use, I was wanting scientific answers as to why use barrier.

badgerboilerMN

Rhomar and others make oxygen inhibitors without the detrimental qualities of glycol. Add it an test it.

John Ruhnke

O2 barrier......

Narroc,

Glen just gave you the answer in his post above. The other tradesman is not educated in the principles of radiant heating. This is very common knowledge amoung radiant contractors. It is one of the first things you learn. The other tradesman needs to learn some more before he can do his first radiant job. Warn your client about him.

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badgerboilerMN

If you are going to spend that kind of money, don't forget to replace the expansion tank - usually the first component to fail) with a potable water expansion tank and lower the tank pressure to boiler system pressure.