In-floor manifold corrosion question (not tractor related)

[MinnesotaEric]

As some of you know I'm a real estate broker in North Central Minnesota. A house that I'm representing the buyer has more corrosion on the in-floor heating manifold than I've ever seen and I'm concerned. Check it out.

The photo on the left shows one run down into the in-floor heating, but once the pipe insulation was removed, the entire manifold was crusted up just as much as what we can see in the lefthand photo. The photo on the right is immediately above the manifold and ties into the manifold and it appears the corrosion is traveling to the unions from the manifold.

Question: Am I looking at electrolysis from a lack of a proper grounding? Dissimilar metals at work?

The system was installed in 2006. In 2018 the boiler was updated to a nice, big Weil McLain.

My concern is if there are any junctions in the cement floor, then could they be crusting up as much, or is the manifold the sacrificial anode for reasons yet to be explained? I'd love to hear everyone's' thoughts and experiences. We have a shortage of tradesmen up here and for this reason, I'm asking the collective brain-trust about the reason for the corrosion on the forum and if I should get the seller to get the manifold replaced? Thanks!

 

[fried1765]

As some of you know I'm a real estate broker in North Central Minnesota. A house that I'm representing the buyer has more corrosion on the in-floor heating manifold than I've ever seen and I'm concerned. Check it out.

The photo on the left shows one run down into the in-floor heating, but once the pipe insulation was removed, the entire manifold was crusted up just as much as what we can see in the lefthand photo. The photo on the right is immediately above the manifold and ties into the manifold and it appears the corrosion is traveling to the unions from the manifold.

Question: Am I looking at electrolysis from a lack of a proper grounding? Dissimilar metals at work?

The system was installed in 2006. In 2018 the boiler was updated to a nice, big Weil McLain.

My concern is if there are any junctions in the cement floor, then could they be crusting up as much, or is the manifold the sacrificial anode for reasons yet to be explained? I'd love to hear everyone's' thoughts and experiences. We have a shortage of tradesmen up here and for this reason, I'm asking the collective brain-trust about the reason for the corrosion on the forum and if I should get the seller to get the manifold replaced? Thanks!

You (or someone else) can clean that up.
Use a steel brush or stainless steel brush, with OSPHO (Phosphoric acid, at your hardware store).
Try to catch the drippings, so they don't etch the concrete floor.
Several applications (in succession), and the copper will look like new.
When thoroughly clean, rub on a light coating of something like PB Blaster (WD-40 is too thin).

This condition is frequently found in hot water heating systems.
I have connections in my hot water heating system that would look very similar to your pictures, if I did not clean them every several years.
Can be caused by a number of factors, including type of flux paste used when built, as well as PH of the hot water.
Assuming the system is anti freeze protected, it might also be a good idea to replace that, as it should contain fresh corrosion inhibitors.

I believe it is correct to assume that there is no copper pipe in/under the floor?
A 2006 installation should have only PVC type pipe used in/under the floor.

 

[dstig1]

Looks to me like those are old leaks that have crusted over.

 

[ruffdog]

As the buyer, I would be VERY concerned.

Corrosion in hydronic system

 

[jaxs]

If I was representing seller and that notation (10.4.2) in bold is from an inspection report,I would advise seller to do as they ask which is exactly what Fried suggested. It hasn't failed so it doesn't require replacement. As for what it look's like in and beneath cement floor,there "SHOULDN'T" be junctions but we know what is and what is supposed to be can be different. It's a shame about shortage of tradesmen because I think a good one might find something(service,load center,appliance ect) has imperfect earth ground and is experiencing an issue that bleed's through those lines in search of earth. If you decide to pursue that possability and can't find a competent electrician,ask the utility company if they will check out their system and possibly reccomend someone to check home. At minimunm,I'd be certain there's a properly driven rod.

 

[rademamj1]

Yes Eric, you are correct, it is an electrical related problem. If metals with different electrical potentials come in contact with water from a dripping pipe, no matter how slow the drip, a weak battery structure is actualy formed and electrons are exchanged between the dissimilar metals, causing corrosion. This occurs depending on the natural electrical conductivity potential of the metals, and the metal with the lower conductivity starts to corrode, just like on the outside of a leaking 12V auto battery.

The obvious solution is to make both pipes the same metals, or more simply switch one pipe on the plumbing connection to PCV pipe....which is a non-conductor. Any plumber can repair this in about one hours work.
What you don't want to do is just clean it all off, because the corrosion will all just come back again.

 

[fried1765]

Yes Eric, you are correct, it is an electrical related problem. If metals with different electrical potentials come in contact with water from a dripping pipe, no matter how slow the drip, a weak battery structure is actualy formed and electrons are exchanged between the dissimilar metals, causing corrosion. This occurs depending on the natural electrical conductivity potential of the metals, and the metal with the lower conductivity starts to corrode, just like on the outside of a leaking 12V auto battery.

The obvious solution is to make both pipes the same metals, or more simply switch one pipe on the plumbing connection to PCV pipe....which is a non-conductor. Any plumber can repair this in about one hours work.
What you don't want to do is just clean it all off, because the corrosion will all just come back again.

And......the corrosion will then not continue to occur, where the new fitting is installed to go from copper to PVC?

 

[MinnesotaEric]

As the buyer, I would be VERY concerned.

Corrosion in hydronic system

Edit: my link diies work either but it goes to the guy asking about "The expansion tank just fell off its nipple."

Roughdog, is this the discussion you linked to? your link wanted a login. Corrosion in hydronic system

Also, this is an in-floor PEX system. At this time it appears that only the manifold/plenum is crusting up. Each PEX run SHOULD (in God's grace we pray and hope) go into the floor and pop back out the floor as one single run without splicing. I cannot know if there is splicing or not, but my Errors and omission insurance doesn't want to experience a $120,000 repair bill because I failed due diligence to investigate and "own" or "understand" what is happening.

 

[MinnesotaEric]

Yes Eric, you are correct, it is an electrical related problem. If metals with different electrical potentials come in contact with water from a dripping pipe, no matter how slow the drip, a weak battery structure is actualy formed and electrons are exchanged between the dissimilar metals, causing corrosion. This occurs depending on the natural electrical conductivity potential of the metals, and the metal with the lower conductivity starts to corrode, just like on the outside of a leaking 12V auto battery.

The obvious solution is to make both pipes the same metals, or more simply switch one pipe on the plumbing connection to PCV pipe....which is a non-conductor. Any plumber can repair this in about one hours work.
What you don't want to do is just clean it all off, because the corrosion will all just come back again.

Nobody uses PVC for in-floor heating plenums in my area. Those manifold plenums are always brass-bronze. This is a brass plenum that is crusted up with stainless rings clamping onto the PEX. Meanwhile, Roughdog is trying to link to something that has me concerned that I cannot see. Meanwhile what you're saying is more-or-less inline with what Fred (and now a local guy who taught boiler-making for thirty years when he saw the photos) is that the outside is coated with flux and that it should be cleaned off and oiled down with something like Fluid-Film or PB Blaster.

 

[rademamj1]

Eric, no login required. I got to read the link without any difficulty. And it is directly applicable to your issue.