Hydronic System Corrosion

Randy McKinney

Can anyone tell me why a system would continually corrode and destroy zone valves, exp tanks, ball & check valves etc. There is no non-barrier Pex tubing, all piping is copper on a baseboard application. The PH of the water used to fill the system is 7 and treatment is added annually during service to maintain the PH. The fill water does go through a conditioning system which corrects the PH from 5.5. There are no leaks in the system which we tested by closing the fill valve and watching the pressure for weeks. There is no antifreeze involved. There are Apollo 3-way purge/ball valves on the system and the caps on the hose threads completely corroded off, and of course the system water isn't even making contact with those caps after the system is purged. This led us to believe the corrosion was coming from external sources but there are no chemicals in the basement, a dehumidifier runs to maintain a reasonable RH, and we can't see any other cause for the problem. I'm open for suggestions!!

Dan Peel

Voo Doo ?

What you are seeing could be electrolysis. Check for stray voltage in your piping, static electricity or heating system being used as a ground station for telephone or electrical. Sounds as if you know what's in your water and the corrosion is extraneous. Look outside the box. Enjoy.....Dan

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hr

How does it present

A corossion that attacks copper iron, and steel is pretty serious.

Mainly the copper and brass zone valves, etc. How does it attack and destroy these? Pitting? Green color? attacking the rubber components of ZV's?

What about iron, little closed cell blisters? Or red rust deposits? Is it softening the cast iron? Black water? Smelly?

I have had some iron bacteria in systems, weird stuff. Ph tests ok but the bacteria eats away at steel and iron quickly. I could scrape away at the pump volutes like shaving ice! Didn't seem to attack copper, however.

It had a terrible sewer type smell, which is the odor the bacteria gives off as it digest iron. Bacteria farts, so to speak Regular hydronic chemicals won't touch it.

A good lab with hydronic or fire sprinkler testing experience should be able to figure that out. Maybe a corrosives engineer. Let us know what you come up with.

hot rod

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John Abbott

Dan is right......

I belive it is electrolosis. have an electrician bond your piping system to the ground at your electic service panel.That should eliminate the problem.

John

Unknown

That's not so wierd.

I've seen what you are talking about and I've been witness to stray voltage causing this type of external corrosion. We use to call it "green desease" in Colorado and it can be measured with a mili-voltmeter. The telephone company installation crews in Boulder would not bond their system to earth ground. They didn't know any better. Miles of copper tubing in downtown were replaced because of this.

Now if there was chlorine present, that's another story. You say there is not . So, It's got to be stray voltage. But, you knew that allready.

hr?,,, "bacteria farts",,, LOL

AIM user name: Radiantfloors

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Randy McKinney

Thanks!

We're going to try grounding the system as was suggested. It seems to be the most likely culprit. Thanks for the great input to our problem!

Larry Weingarten

resource

Hello: You might try going to "nace.org" (National Association of Corrosion Engineers)and looking under "academic links". It could be a way to find a good local corrosion engineer.