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Thread: Corrosion inhibitor in closed loop radiant - no need for oxygen barrier pex?

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    DIY Junior Member pex4me's Avatar
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    Default Corrosion inhibitor in closed loop radiant - no need for oxygen barrier pex?

    Anyone ever heard about using a corrosion inhibitor in radiant installations that use non-oxygen barrier pex and cast iron components? A friend was advised to use Chemsearch 777 (http://www.chemsearch.com), which is advertised there as "Chemsearch® 777 provides corrosion protection in the piping of large closed loops. Prevents exchangers and zone valves from plugging due to corrosion. Reduces corrosion damage to water pump impellers and seals. Chemsearch® 777 is a non-chromate inhibitor, specially formulated for corrosion protection in copper, steel, and multi-metal systems, whether they are airtight or not. Also has a color indicator that becomes colorless if system pH gets too low and a borate buffer to maintain the pH of the recirculating water in the range of 8.5 - 10.5."

    If this could work, folks could save a lot of money by not using oxygen barrier pex. Thoughts?

  2. #2
    Journeyman & Gas Fitter Doherty Plumbing's Avatar
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    Quote Originally Posted by pex4me View Post
    Anyone ever heard about using a corrosion inhibitor in radiant installations that use non-oxygen barrier pex and cast iron components? A friend was advised to use Chemsearch 777 (http://www.chemsearch.com), which is advertised there as "Chemsearch® 777 provides corrosion protection in the piping of large closed loops. Prevents exchangers and zone valves from plugging due to corrosion. Reduces corrosion damage to water pump impellers and seals. Chemsearch® 777 is a non-chromate inhibitor, specially formulated for corrosion protection in copper, steel, and multi-metal systems, whether they are airtight or not. Also has a color indicator that becomes colorless if system pH gets too low and a borate buffer to maintain the pH of the recirculating water in the range of 8.5 - 10.5."

    If this could work, folks could save a lot of money by not using oxygen barrier pex. Thoughts?
    I am not sure what about that description makes you think you don't need oxygen barrier pex? That is for corrosion resistance.... not for oxygen blocking or however you want to think about it. The problem with steel piping systems in boilers systems is that no matter what you do you can NEVER get 100% of the air out of the system (even with air scoops) so you will always have some level of corrosion... but not with plastic piping.

    People might save $ in the short term but could THOUSANDS of dollars of damage in the long term.

    Why would you cheap on out parts you're going to bury in the walls/floors? Silly if you ask me.

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    For the few extra pennies Oxy barrier heat pex cost, why would anyone trust a chemical additive? Besides that the inhibitor does would not stop oxygen migration. I have changed a pipe of boilers that were ruined beyond repair because someone was either too cheap or stupid when the bought the pex.

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    Moderator & Master Plumber hj's Avatar
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    Default chemical

    In a closed system, the only air/oxygen introduced is what is in the water. That air is released when the water is heated, and the air eliminator removes it from the system. Therefore, the "inhibitor" only has to deal with a limited amount of "potential" corrosion if all the air is not removed. Without the oxygen barrier, the process could be continual so the material would have to be constantly replenished to maintain the protection. It would be a classic case of "penny wise and pound foolish".

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    DIY Junior Member pex4me's Avatar
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    Quote Originally Posted by Peter Griffin View Post
    For the few extra pennies Oxy barrier heat pex cost, why would anyone trust a chemical additive? Besides that the inhibitor does would not stop oxygen migration. I have changed a pipe of boilers that were ruined beyond repair because someone was either too cheap or stupid when the bought the pex.
    When my foundation slab was put in, I didn't know any better and so, am stuck with non-Oxygen barrier pex. The neighbor did the same thing, but he beat me to the actual hooking up of the slab, ergo the question.

    When I discovered (in horror), the mistake I made, I just vowed to use pumps with stainless steel or brass volute's and a brass or SS boiler.

    The fact that his professional dumped a gallon or so of this chemical and instructed him to go with cast iron pumps just blew me away, so I figured I'd ask here.

    Now I am in search of a SS or brass electric boiler. I've only picked out the pumps at this point - the Grundfos Alpha SS models.

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    Retired Defense Industry Engineer jadnashua's Avatar
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    I don't think a lot of oxygen will migrate through the pex in the slab, but it has to exit it somewhere to make it to and from the boiler...good luck.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

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