Got something in the water!

Tom_133 · May 26

I installed a Rinnai I-series boiler a few years ago, probably 6 or so. He has had a couple minor issues, like a few circs, and an internal pipe going bad in the boiler. He has been using his fuel company to get the work done. Recently he reached back out to me, and here are a couple pics of the circs internally. What the heck causes this? He may also have onyx tubing in the slab??

Alan (California Radiant) Forbes · May 26

That's from oxygen intrusion, either from the Onix tubing or somewhere else.

Onix has an aluminum oxygen barrier, but from what I've heard, oxygen still gets through.

mattmia2 · May 26

either oxygen ingress through tubing that isn't oxygen barrier or that has an oxygen barrier that has somehow failed or it is leaking somewhere and getting a lot of makeup water that brings oxygen with it.

hot_rod · May 26

rust! Caused by sir (oxygen) getting into the system

Is it an open system, combination dhw and heat?

Connected to a fill valve?

Jamie Hall · May 27

Well that's a right mess. As has been said, mostly oxygen corrosion. Which is all very fine, but i think you may have a horrible time getting it cleaned up, if you can do it all. Hate to say it, but it may be cheaper to replace it.

hot_rod · May 27

The earlier rubber pre Onix, Entran tubes could do that to a system in a years time! The higher the operating temperature the more O2 they suck.

Those sludge, rust deposits are probably everywhere in the system. There are some cleaers specifically for rust deposits, it may take a few treatments and power flushings.

mattmia2 · May 27

if it is the tubing you can either set it up as a system with no ferrous components, probably using a heat exchanger or you can add inhibitor to it and keep adding inhibitor. as the oxygen scavenger in the inhibitor is consumed you have to add more inhibitor s if you want to keep the system from consuming itself you need to periodically add more inhibitor.

make sure it isn't just leaking first.

Tom_133 · May 27

Thanks All,

I had that sneaking suspicion. A heat exchanger and a thorough cleaning and oxygen scavenger is my suggestion. We will see what they say!

EricForman · June 11

Wow, scary… I added a PEX-in-slab zone to my Viessmann Vitola BiFerral 27 years ago and haven't changed a circulator or looked inside a pipe ever since. Should I worry about oxygen getting into ~1999 vintage PEX?

Dave H_2 · June 11

Cleaners (chemical and mechanical), inhibitors, isolation (plate heat exchanger) and stainless components (circulators and expansion tank) is the direction I would go. Cast iron circs and and such can be on the boiler side of the heat exchanger.

Also check any of the tubing you could find for pliability, if rigid, be very careful and consideration of back-up heat may be needed.

Seen it many times over the years with tubing systems where someone saved a few cents per foot and used non-barrier tubing.

This could also be an indication of a major leak in the system without any visible leaks around, pressurize the system and turn off the prv.

@EricForman look at the pipe for some of the markings and look for a DIN number or the words oxygen barrier or at least the brand and type of pipe, there will be somewhere here that can help identify. I would assume that you are ok 27 years later!

hot_rod · June 11

A circulator in that condition is beyond any chemical cleaner. Probably any ferrous component in the system will look like that.

DCContrarian · June 11

This is why I'm an advocate of leaving the makeup water shut off. And taking the handle off of the valve and hiding it. Makeup water masks bigger problems.

Lance · June 12

It all starts with who designed, who modified, who built, who redesigned, who modified again and who applied changes to the system. Solution (s)? No doubt there are many. Would this be a band aid fix, or heart surgery, or start over solution? My two basic solutions to this problem and one is guaranteed, the other is my warranty expires 1 minute before I complete the repair. Money is always limited when problems and solutions seem to never end. We come up with many solutions, but who really has identified all the causes and issues first. Not all will be revealed until some changes are made. So my no warranty solution(s) is repair the obvious, due some testing, flush if needed, test again, takes its temperature, check its pulse, order some more tests and call me in the morning. My guaranteed solution is to tear out and start over. This sounds like a patient that needs long term care. Perhaps some financial assistance to keep up with the bills. Problems like this are why people sell their houses instead of fixing them.😕

kevineggerth · June 15

Im surprised no one mentioned the obvious from Dan's book Pumping Away. Could be improper piping thats drawing in the air when you see this much damage. Additionally there's likely cavitation and velocity problems.

mattmia2 · June 15

usually if that is happening it doesn't find its way back out and you end up with high pressure and a dribbling relief valve.

LMacNevin · June 16

Good quality PEX with an EVAL or EVOH oxygen barrier that meets DIN 4726 (German standard) should be oxygen tight for the life of the PEX, estimated at 50+ years in most situations.

Tom_133 · June 16

https://forum.heatinghelp.com/discussion/comment/1898546#Comment_1898546

Because he has some onyx tubing it's more than likely that. Also, I make mistakes here in there, but I have been "pumping away since 2003!" Yes, I installed the system, and yes, that should be on a bumper sticker!

Intplm. · June 16

It may also be the wrong circulator. The head should be brass or stainless steel.

Got something in the water!

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