# Boiler corrosion



## Hessplumbing

I have a friend of mine that put in a boiler for a customer who is a sue happy jack a%$!!! The boiler was installed five years ago in may. It is an electric boiler with staple up onix tubbing on crawl space. The problem is the owner and some plumber from out of town come put in some baseboards hooked to the in floor heat because he said the house doesn't get hot enough. Well two years after the base boards were installed they rusted out and the expansion tank and boiler are showing signs as well. The other plumber said onix tubing is not Oxygen Barrier tubing and thats what caused it. Well i know thats not eh problem, the boiler has not been serviced since it was installed 5 yrs ago there for the is probably no glycol in system. The ph on the make up water is 7.7 the hardness is 29 which is very hard I think its the hardness of the water that has caused this problem but I'm not 100% sure thats why i need your input. The owner also said the insulation was installed wrong and there are no heat shields. I was told the don't put heat shields on onix just pex. He said the insulation is suppose to be tight against the floor joist touch the onix. I was taught by the good people at the zurn company that you want a heat chamber between the pipe and insulation. But maybe I'm wrong but any idea on corrosion would be great thanks guys. shawn


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## Redwood

Onix Tubing is PEX-AL-PEX so it does have the required oxygen barrier.
That's not the problem...

Could be leaks and constant water replenishment or water conditions...


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## ToUtahNow

Redwood said:


> Onix Tubing is PEX-AL-PEX so it does have the required oxygen barrier.
> That's not the problem...
> 
> Could be leaks and constant water replenishment or water conditions...


Except that it is a Cross-linked Durel EPDM (synthetic composite type material) as oppose to a PEX.

Ethylene-Propylene-Diene-Monomer

Mark


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## Redwood

ToUtahNow said:


> Except that it is a Cross-linked Durel EPDM (synthetic composite type material) as oppose to a PEX.
> 
> Ethylene-Propylene-Diene-Monomer
> 
> Mark


Ahhh yea my bad...
So would that be the cause of corrosion?
As it does have the required Oxygen barrier...


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## ToUtahNow

Redwood said:


> Ahhh yea my bad...
> So would that be the cause of corrosion?
> As it does have the required Oxygen barrier...


To be honest, I've read his post a couple of times and I'm not sure which issue he wants addressed. I doubt the Onix would have anything to do with corrosion at the expansion tank or the boiler. As for the installation, it should be tight against the floor with the installation directly below it. The problem is, if it was undersized to begin with, the rest doesn't matter.

Mark


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## Redwood

ToUtahNow said:


> The problem is, if it was undersized to begin with, the rest doesn't matter.
> 
> Mark


Yep... Who knows what is wrong with it?
A lot of details missing...
Sizing info, are the baseboards running at radiant temps, elements gone bad????

But it's not the tubing...


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## MarkToo

Redwood said:


> are the baseboards running at radiant temps



Good question. What do you want to bet that's a major factor?


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## rjbphd

Too many variables on this job.... didn't have a real hydronic heating company do the job... insulations are never suppose to be tight against the bottom of floor where heating tubing located.. must use transfer plates to prevent heat stripings.


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## Plumbworker

I've see where expansion tanks fail the system over pressurizes the relief valve dumps outside and the makeup is constantly filling the system with fresh oxygenated water..

By the way the watts onix tubing does has a oxygen barrier i believe its aluminum.. and yes the staple up should have a air space between the insulation...


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## Hessplumbing

They don't make heat shields for onix tubing from what i was told just heat shields for pex.


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## ctj

Over the past years ive been running into a lot of these systems where the water is really brown (rust). The boiler piping is being ate up expansion tanks are being ate out yearly the only thing they all have in common is the blak rubber tubing. Some have Onix some have what we call spa ghetti tubing its quarter inch tubing somecantfind the brand. Some is five years old to ten years. Cant find any direct relation except it the black tube (rubber). The say there is a oxygen barrier but you cant prove it by me. Right now im working on a spaghetti yube system it kept eating out the nipples to the boiler. Last year pulled out a leaky nipple and the in side of the boiler was basicly just flat rotten you could just scrape off the cast iron. This year one last leaky nipp. and in a month the boiler its self has a pin hole. Going to try salvage the infloor put in a knight boiler with a plate heat exchanger to islate it at least the boiler will survive. They are ok with redoing the infloor. Had another with a teledine laars endurance ten years plugged up one coil in the heat x cut it apart everything plugging it was magnetic put in new boiler installed fernox filter and some chemical keeping a close eye on it. Again black rubber i believe that is onix. Either system is fed by domestic when there is a problem(leak) you know theres no heat both about once a year. Any ideas in this similar problem.


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