Fosta Pex Sludge

oilguy

Wondering if anyone has seen sludge that has built up on the inside walls of Fosta Pex? We were adding additional baseboard to a relatively new system, and could not get any flow through the loop. After cutting out the Pex we found it to be almost completely plugged . This was the case on two lengths of Pex, but not in the copper runs. The Pex also changed color to a yellowish color and seemed to bubble on the outer layer. It almost looked like it was overheated. Just curious as I never expected to see a build up on the Pex. Thanks in advance.

wcs5050

Yes I heard about this in a radiant system. I guess the solver was able to force through with air then run some kind of cleanser to get the sludge off of the pipe wall.

GW

I had this happen 5 or 6 years ago, brownish flakey matter was stopping flow. Vega rep never heard of it. I still have some of the brownish matter in an old Duncan Donuts cup

oilguy

Gary did you use a cleaner to get rid of it or replace the pipe. This house has 2 more zones with limited access. Not really sure what to try that won't eat at the Pex

4Johnpipe

Im pretty sure Eric Aune used Fernox with air...several applications due to the complete stoppage

GW

The situation went south. The homeowners were nice about it, but when the Mrs. dropped the "it's your dime" phrase on me, I stuck my heels in the ground. I told the builder, who was still involved with the project, that I needed to know what caused the sludge before I did anymore work (I already had 10 hours or so spent, no billing was created). I never heard a peep about it again. The builder apparently got someone else to fix it. I was moving on from my relations with builders anyway

The system was all new, a new G115 Buderus, new air handlers, some existing Bb.

Maybe someday I'll know what happened.

hot_rod

The only way to know is have the sludge analyzed. It could be from the original fill water with all the residue inside the piping components.

I don't know any means for the tube to "grow" sludge?

Commonly it is caused by large amounts of make up water being added.

If any of the sludge sticks to a magnet it is magnetite and formed by O2 getting into the system and corroding any ferrous components.

Air vents sucking air in the system possibly?

GW

My situation, highly unlikely it was excessive make up water.

I should try the magnet to my coffee cup findings. And maybe burn a flake too to smell its
general odor. If anyone knows a chemist (free diagnosis, you know, your son or daughter ) I'll mail you a portion of my secret stash.

GW

a Bump of all Bumps----any other Fosta pex issues out there? We just did a job with Fosta running to the attic--had a rough time purging the lines. I ate some more labor.

jpulls11

I spent 4 hours at a friends house purging 1/2” fosta runs. Previous owner converted from electric to hydronic. They must have went with 1/2 to save money. Either way, a lot of air and chemicals got the loops to finally heat. Added a dirt magnet to continue with the chemicals.

GW

thats a bummer. Someone out there must have an official answer as to why the fosta is failing, and it seems random

hot_rod

if the sludge is from the tube deteriorating then you would see thinning and cracking of the tube

I think having the sludge analyzed would indicate if it is metal, minerals, or plastic particles

There was a batch of plastic water heater dip tubes that would break down into particles and plug faucets, etc, so anything is possible

Contact Lance at the Plastic Pipe Institute. He worked at Rehau previously so he knows pex well. Maybe they do testing or could send you to a lab?

GW

thanks, not a huge matter- knowing the answer won't help at this point. My 1st encounter with bad fostapex was 18 years ago, I think we are on case #5. We got the heat going but it was rough.

hot_rod

GW said:

thanks, not a huge matter- knowing the answer won't help at this point. My 1st encounter with bad fostapex was 18 years ago, I think we are on case #5. We got the heat going but it was rough.

Were the other systems slugged also ? 

kcopp

I have only had 1 case of mudding up. It was in a 24" section that I remotely hooked up an expansion tank. There was a 90 that had a bunch of junk in it. The issue was that the line was blocked and the relief valve was reliving onto the floor.
I cut open the pipe and viola... This was a 10 yr old system.
Most of the failures I have seen are sections of pipe that delaminate.
Some in cases they were bent beyond the proper radius.

GW

Bob yes it's been a while since our last encounter but yes we simply purge out little chunks---and every time we are in a hurry, I have yet to put a magnet on the giblets yet I presume it's non-metallic. This job: I wasn't on this one and my guys left some 'evidence" sitting in a small cup at the job.