Heavy deposits / dezincification in valve during new build

[Nate E]

I am in the process of a shower remodel. The rough in valves have been installed with the gray test caps (delta Multichoice) and the system pressurized for 2 months.

Today I removed the caps to install plugs after the wife complained about getting slugs of cold water in the other bathroom. We have what looks to be heavy deposits or a reaction occurring in the valve body.

I’m trying to understand what’s going on. We don’t have a water softener, but haven’t noticed major issues with minerals. The old valve of 25 years didn’t have any issues. Water was likely being pushed back and forth across the valves due to pressure differences in the hot and cold side. Still, this seems excessive and has me concerned about issues, after cleaning, once the cartridges are installed.

I’m tearing them out to soak in vinegar. Surely there’s deposits where I can’t get with a rag.

Any experience, thoughts, or advice are appreciated. Is there something that could prevent this happening? I expect a few more months before the shower is done.


Overview:

Valve #1:

Valve #2:

 

[Nate E]

Removed for cleaning since the deposits weren’t wiping out. Something is obviously not right.

 

[Sponsor]

 

[Jeff H Young]

Could be from air. How long was this sitting monthes, weeks close to a year? is the house all pex been repiped just for a bathroom

 

[Tuttles Revenge]

I would be getting the water tested to see what is reacting with the brass. The cold water slugs are from that valve allowing hot water to pass into the cold system since there is no cartridge or plug on one of the inlets. RP46079 is the part number for the plug.

 

[Nate E]

Could be from air. How long was this sitting monthes, weeks close to a year? is the house all pex been repiped just for a bathroom

Appx. 1.5 months sitting. Just the bathroom was piped with PEX. Thought about air, but everything was topped up. I drained water from the shower arms.

After soaking and wiping out the white stuff, the surface underneath is pink.

 

[Nate E]

I would be getting the water tested to see what is reacting with the brass. The cold water slugs are from that valve allowing hot water to pass into the cold system since there is no cartridge or plug on one of the inlets. RP46079 is the part number for the plug.

Good call on the plug. I was installing the plugs when I made the discovery.

If it’s the water, wouldn’t we expect to be seeing all kinds of issues? Surely there’s quite a bit of brass in the system and it’s been operating for 25 years.

Maybe flux from soldering the adapters 10 feet upstream where the copper terminates? Seems like a long shot, I mean these things are installed in thousands of homes using the same basic method. The adapters at the valve are threaded on with PTFE tape and dope. I’m careful about cleanliness, but didn’t do any flushing.

This has me scratching my head. This looks like dezincification based on my research (no experience).

 

[Jeff H Young]

the flux and heat puts out a corrosive smoke but I cant put a finger on it a small amount of water with air space I think might allow this condition, more like installed in hundreds of thousands of homes.
Ive never used the plugs rp 46079 only caps rp 46078 or the cartridge but good call to install one plug that way your valve is under constant pressure and you arent mixing hot and cold water

 

[Nate E]

the flux and heat puts out a corrosive smoke but I cant put a finger on it a small amount of water with air space I think might allow this condition, more like installed in hundreds of thousands of homes.
Ive never used the plugs rp 46079 only caps rp 46078 or the cartridge but good call to install one plug that way your valve is under constant pressure and you arent mixing hot and cold water

This is the best I can come up with too. Some acidic water from excess flux or some crap in the lines sloshing around with trapped air. I bought some litmus paper and will check PH of my supply. We are on city water which is generally pretty good.

Learned a bit about dezincification.


All I can think do at this point is a good flushing before reinstalling the valves.

 

[Jeff H Young]

I think you are safe a good idea on some flushing! once that stuff gets heat from torch its gotta be strong inside the pipe plus who knows how much flux he used not un common to see it thrown on sloppy .
I think you did over kill but totally understandable

 

[Nate E]

My plumber (me!) does probably use a little more flux than is necessary, maybe a bit of extra heat as well. He’s getting experienced quickly.

I called Delta. Their advice was to clean out with 50/50 vinegar and water, then flush. Seems like we’re on the same page.

Hope this helps other new folks. Make sure to flush the system asap.

 

[Tuttles Revenge]

Could be flux. I didn't think of that since I only saw PEX in the photos with threaded connections. I have never flushed out my solder connections much. But I hardly get any more flux on a joint than needed.

We bought a bunch of those rough in plugs but hardly ever use them because we started purchasing our rough in valves with service stops and just turn one side off for testing and until we set trim with the cartridge.

 

[Jeff H Young]

Right the plugs are un needed if it has stops . I noticed stops are way more common nowadays