How do I know if my green Central Boiler 1" Pex tubing has an oxygen barrier?

[mpoyneer]

I just replaced my Central Boiler Classic outdoor wood boiler with an Econoburn 150. The old boiler was an open system, and the new boiler is closed and pressurized. I know I need to keep oxygen out of the system, but I re-used my old (circa 2004) underground supply and return lines that came with my Central Boiler as I didn't want to dig up my yard and spend more money than necessary. How do I know if this green pex tubing has an oxygen barrier?

 

[in hot water]

can you see any standards printed on the tube? Look for a DIN 4726. Does it have a shiny surface, that is typically the EVOH barrier that is applied for O2 protection.

Dull surfaces are usually non barrier tube unless the barrier is built into the tube wall like a pex al pex tube.

I'm guessing if it was supplied with an open system it is non barrier.

Isolate it with a HX or use a chemical solution with O2 scavangers. But chemical romances can get complicated and expensive.

hr

 

[mpoyneer]

I called Central Boiler and they said that all of their green pex tubing has an oxygen barrier...but I don't believe anything from them, so I still need to find markings on the pipe. I know, I know: "if you don't believe them, why did you ask them?"

 

[in hot water]

You might find a manufacturers mark or name on the tube and work from that end. Rifeng was one off shore company that supplied a lot of the OWF brands.

hr

 

[mpoyneer]

The tubing shows the following markings:
Central Pex 1" (CTS) Potable Tubing SDR-9 NSF 8137 5 ASTM F876/F877 F1807/F2098 80PSI @ 200 Degrees F 100PSI @ 180 Degrees F LM 40799 Cat# 2342

The "Potable" part makes me nervous - most potable pex doesn't have an oxygen barrier, correct?

 

[Jesse-M]

Probably going to catch some h** for this statement but...I think O2 protection is a bit overrated......IMO

 

[in hot water]

Without knowing the source it would be hard to tell. I don't see the DIN number listed? Perhaps the most knowledgeable person regarding this is Mr. Pex, go to www.mrpex.com and maybe drop him a line. Perhaps he has a method to test to test the tube.

Here is a link to one of his articles for years ago. www.mr.com/pdf/Diffusion.pdf


There is no question that non barrier pex will cause systems components to fail prematurely. We saw this first hand back in the 1980 when PB polybutylene and other non barrier rubber products were used. On high temperature systems the results were often seen within the first year. Most often the expansion tanks would pinhole being a thin walled steel product.

Pumps would corrode so badly that impellers would jam, usually the second failure. Then threaded connections would corrode away around the thread, at the thinnest part of the wall dimension. Often times expansion tank nipples would corrode right out of the thin steel tanks and the tanks would fall to the floor. Even cast iron and steel boilers would fail after some time.

I've seen threaded nipples snap off at the cast iron boiler connections.

The byproducts of all the corrosion was a thick red sludge that would gum up valves and eventually plug the tube. The small diameter radiant tubes would plug to the point that they could not be flushed out. We tried pressure washers at 150 psi and more to flush plugged tubes in some cases. Almost as if someone put concrete in the tubes Many of those early radiant inslab systems had to be abandoned and baseboard or forced air systems retrofitted.

So the question was not IF components would fail from non barrier tube use, but when. The water temperature is a big factor. The high operating temperature baseboard systems, for example would fail rather quickly, lower temperature could go a few years before leaks developed.

Those radiant manufacturers in denial tried to head off the inevitable with corrosion inhibitor products. These did have some sucess but were expensive, possibly toxic and required frequent "boosts" depending on temperatures again.

I'm not sure the cost difference between barrier and non barrier would balance the failure potential. Perhaps if you are installing thousands of feet of tube? But even then isolating the non barrier tube with a plate HX and non ferrous pumps, etc would prove to be a better solution.

hr

 

[heaterman]

We just installed a CB for a guy using their green outdoor tube. (maybe called LogStor?) There was nothing on it indicating that it was barrier tube. From outward appearances it does not look like it has a barrier and I treated it as such by isolating everything inside the building with a plate HX.

 

[bigburner]

I have worked with that chit before also, it don't look like any other Pex that I have ever seen. Like a frozen garden hose

 

[heaterman]

Probably going to catch some h** for this statement but...I think O2 protection is a bit overrated......IMO

The dollar amount of all the system components we have replaced, such as boilers, circulators, pipe, valves of various types, etc., due to non sealed systems is in the low six figure range. It is not a myth.

 

[juddspaintballs]

I have OB and non-OB PEX sitting in my basement. The non-OB PEX was for some plumbing for my upstairs bathroom and the OB PEX was for my OWB that I'm almost done installing. The non-OB PEX is dull and the OB PEX is shiny on the surface. Both are red in color.

 

[heaterman]

I have worked with that chit before also, it don't look like any other Pex that I have ever seen. Like a frozen garden hose

Yah! My boys see that stuff on a job and they say "time to wrestle with the anaconda". It is gnarly junk t work with. About average insulating value though. Much better than the "Timesaver" stuff with the foil foam wrap.

 

[barnartist]

I have 2 short section of questionable pipe myself. How does one know when a flat plate HX is ok or holding up? This would be the first place I would suspect trouble.

 

[Fred61]

So the question was not IF components would fail from non barrier tube use, but when. The water temperature is a big factor. The high operating temperature baseboard systems, for example would fail rather quickly, lower temperature could go a few years before leaks developed.

Those radiant manufacturers in denial tried to head off the inevitable with corrosion inhibitor products. These did have some sucess but were expensive, possibly toxic and required frequent "boosts" depending on temperatures again.
hr

There may be exceptions to this but I've always thought that the hard and fast rule was that any chemical reaction is accelerated by heat and oxidation is one of those reactions. Electrolysis is another reaction that's working against us.

 

[heaterman]

The tubing shows the following markings:
Central Pex 1" (CTS) Potable Tubing SDR-9 NSF 8137 5 ASTM F876/F877 F1807/F2098 80PSI @ 200 Degrees F 100PSI @ 180 Degrees F LM 40799 Cat# 2342

The "Potable" part makes me nervous - most potable pex doesn't have an oxygen barrier, correct?

You are correct to be nervous. I have not seen barrier pex labeled "potable except for Viega's PAP product.

I did some checking with the local CB dealer, who had to call the factory to find out, and he was told it is non barrier tube.

 

[heaterman]

I have 2 short section of questionable pipe myself. How does one know when a flat plate HX is ok or holding up? This would be the first place I would suspect trouble.

The plate HX will "hold up" OK but what it may or rather will do eventually is plug up. Once it plugs it's done. They make a nice rustproof boat anchor at that point because if you can't get any "solvents" to flow through the thing, you can't clean them out.

Set up your piping at each of the corners on the non barrier side like this. From the HX you want a union, then a tee with a boiler drain, then a ball valve. Piped like that it's no big deal to hook up a pump and hoses to circulate some type of caustic cleaner through the thing to flush it out a 2 or 3 times a year. Bear in mind that the buildup occurs even when the system is "off".
We've found that some of the heavier duty product for cleaning boilers will work well and for those of you who are in dairy farm country, the dairy supply stores have acids available that are made for cleaning stainless of all types as well as heat exchangers specifically. "Sizzle" is a brand name available at most plumbing/heating supply stores. Don't waste you money on CLR or something like you would find at a Big Box store. Wear rubber gloves, apron or rain suit and goggles when you use it because it can "boil" to a rather nasty degree.