Rust is clogging pipes, valves, pumps .

Discussion in 'Boiler Forum' started by Ablumny, Apr 21, 2012.

  1. Ablumny

    Ablumny New Member

    Messages:
    4
    Location:
    New irk, TX
    Hello

    Each year it seems I have to replace the pressure valve, circulator pump or black pipe near my boiler. Each time, the rust has plugged something up. This year, I call my service guy in to fix what I tought was a problem with the pressure valve. Turns out, everything from the boiler to the copper that heads it to the radiators had to be replaced. Every inlet and outlet for all the black pipe, t's, elbows, valves, tank and the circulator pump was clogged with rust. A couple of the black pipe ends were rotted completly. Lucky they didn't bust open. Service guy suggests a whole whole water filter to remove the minerals that may be causing this rust build up.

    This is a closed system I thought so I'm not sure how that'll help. But I can't explain how this rust builds up like this.

    Any advise is appreciated!
    Andrew
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,917
    Location:
    New England
    Rusting pipes aren't particularly impacted by minerals in the water. You have a leak in the system that is likely constantly adding fresh water. Fresh water brings new oxygen. New oxygen causes the iron to rust. If it was truly closed, any impurities in the water would get 'used up' and reach equilibrium with the rest of the system. No oxygen, no rusting. The pipes could last for decades if there are no leaks and no new oxygen getting into the flowing water inside the pipes. Now, water on the outside will always rust things, since the air contains more than enough to generate rust, but inside, it should be good.

    Fix the leaks, your problem should go away. the path to reaching equilibrium may take longer if your water's pH is low. If that's the case, a filter to neutralize it might help, but it wouldn't be to remove minerals, it would add some to neutralize things. There are some 'conditioners' designed for this that are probably more effective that could be added when you fill the system.
  3. Ablumny

    Ablumny New Member

    Messages:
    4
    Location:
    New irk, TX
    Thanks Jim. I felt I might get that reply. Half my lower level is on a slab. Although I initially didn't pay to much attention to it, while redoing the flooring over the slab, I noticed a couple of warm spots on the concrete. I now suspect the pipes are leaking in or under the concrete. A leak anywhere else would be obvious I suspect.

    If this is true, how in the world does the leak get isolated and fixed in the concrete slab!
  4. BadgerBoilerMN

    BadgerBoilerMN Master Hot Water Mpls,MN

    Messages:
    303
    Location:
    Minneapolis
    Whereas it is true that fresh water will create rust (where ferrous metals are used in a hydronic heating system) it is not necessarily the problem in every case. Fresh or makeup water should be added to a hydronic or radiant floor heating system seldom if ever. If components are failing a diagnosis and remedy should be ascertained before the work is performed.

    In the very early days of Modern Radiant Floor Heating - mid 80s for the most part. Polybutylene (Pb) was the tube of choice and served very well in that capacity. PB was made from a very stable and well suited product made - and still made - by Dupont. PB was the perfect radiant floor tube except for the fact that it lacked an oxygen barrier and therefore was not "idiot proof". When using PB we had to use non-ferrous pumps and other components or isolate the PB from ferrous components - usually employing a stainless steel heat exchanger.

    If your radiant floor tubing is grey in color, it may be the cause of your rust. Not all PEX has and oxygen barrier. So check the pipe for the DIN 4726.070 Oxygen Permeation rating on the tube.

    Naturally it is easy enough to fill the system, shut off all supply and check for leaks. Cleaning up the residue takes special cleaners available at most established hydronic/plumbing heating supplies. We have been using Fernox products for routine residential boiler maintenance for the past few years.

    Unfortunately there is no stop-leak for and brand or type of radiant floor tubing. Luckily, leaks are rare and nearly always self inflicted.
  5. Ablumny

    Ablumny New Member

    Messages:
    4
    Location:
    New irk, TX
    Appreciate the feedback. No radiant flooring here. What I do have is a copper in or under a concrete slab from one radiator to another and warm spots on the concrete. Since I don't see a leak anywhere else in the system and I have this on going rust problem I suspect the copper in the concrete.

    I'm going to turn off the fresh supply and see what the pressure guage does before I call in a pro.

    Thanks
    Andrew
  6. Smooky

    Smooky Member

    Messages:
    598
    Location:
    NC
  7. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,917
    Location:
    New England
    Autofill valves can mask a problem. Under ideal conditions, they never need to add water, so they're not needed. But, if there's a leak, it will keep adding fresh water to maintain the design pressure, adding oxygen, creating rust. From what you've said, sounds like you'll notice the pressure slowly drop once you close the shutoff to the autofill.

    Now, finding and fixing a leak in or under the slab, is problematic. Sometimes, it's easier to bypass it and run a new line through walls, or along the ceiling, or somewhere else (maybe along the ceiling in the attic).
  8. Ablumny

    Ablumny New Member

    Messages:
    4
    Location:
    New irk, TX
    I think you said it right! I couldn't leave the thing off for as long as I wanted but for the few hours I did, the pressure did not maintain. I can't feel the warm concrete thru the finished flooring, i did when the concrete was xposed and i only have one run of copper in/under the slab and no other leaks in the rest of the house, I'm going with a leak in that run. Plan is to bypass up the walls and across the attic.

    Thanks

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