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Draining water from boiler almost black

Brian_68 Member Posts: 2
I have a 17 year old peerless boiler for baseboard heat. As I was bleeding one of the runs, the water exiting was almost black with lots of sediment. It was similar to the black that comes off a spent flapper valve in the toilet. The boiler will also release some water from the relief valve from time to time (I think I have an aggressive fill valve) and for the first time this year there is a lot of dirty stuff on the bottom of the pail. Any thoughts would be appreciated.


  • An agressivew fill valve....

    Sounds like a sticky predicment to me...

    If you have a leak in your system, you need to find it and fix it.

    If your fill valve is being aggressive, your relief valve should tell you when and where.

    The old timers call that black stuff "Boiler Gold". I call it that black stinky stuff that doesn't wash off.

    Might consider water treatment. But if you have a leak in your system, you need to fix that first, before your boiler tells you about it...

  • RonV
    RonV Member Posts: 16

    Your description of the black stuff sounds exactly like the stuff I had in my hydronic system pipes, near the boiler. The problem was that the expansion tank, mounted very near the boiler, which is the type with a rubber diaghram, had suffered a failure of that diaghram and some of the rotted rubber, in gooey and granular form had found its way into the circulating water in the pipes. The failure of the expansion tank also caused occasional operation of the pressure relief valve on the boiler since it was no longer regulating the pressure. Do you have an expansion tank?
  • Brian_68
    Brian_68 Member Posts: 2

    There is an expansion tank located above the boiler. It is air charged. I don't see a leak, save for the relief valve. Is there a way to check the tank? I hope this can go through the winter, Id hate to take the system down for long. I could attach a new one, how long would that take? Thanks for the imput.
  • Was there any

    rust colored water when you drained or purged the system ? That is the deifinitive sign of a prolonged leak .

    This sounds more like the normal stangnant primordial stew we see from decades old system water . Dark in color and smells like bad onions and stomach bile . How much sediment was flowing out with the water ?
  • Jeff Lawrence_25
    Jeff Lawrence_25 Member Posts: 746

    Maybe I didn't spell it right.

    That black water that came out of your boiler was near gold. It's been de-oxygenated completely, among other things.

    It's gross, disgusting stuff that stains anything and everything it touches. It's also completely deactivated and near perfect for your system.

    Understand, this is only my opinion. The real brains in this part of the industry know what it really is.
  • RonV
    RonV Member Posts: 16

    Brian, I'm not a pro, just another homeowner, so call in a plumber if you think something is faulty. Having said that, I'll tell you what I did. I checked whether or not the expansion tank had failed by briefly, very very briefly, pushing on the center pin of the air charging port on the end of the tank. This port is identical to the air filler on your car's tires. Just give it a very quick little tap, for less than a half second. In my case, it immediately spat out water, which of course shouldn't be there. With my tank, the rubber diaghram should completely isolate the water from the air and only if the diaghram has failed would I have water in the air part of the tank.
    Unfortunately, if it has failed, this would certainly cause your boiler's relief valve to occasionally leak water as it is doing its job properly, letting water out when the pressure gets too high. Is there a pressure meter on your boiler or on your pipes near the boiler? If so, the reading should be quite steady all the time, plus or minus a few pounds. If it goes up near 30lbs, this probably indicates this problem with the expansion tank (could be other things too, so we'll just call this one clue).

    I replaced my own, but there were some things to watch out for. For one thing, if there is no shutoff for the expansion tank, you have to isolate it somehow and drain down the system water to take pressure off the tank and so the water won't come roaring out of the pipe when you pull the tank off. The next thing to worry about is that you have to use proper wrench practice to insure you don't loosen anything besides the tank. You know, like back-wrenching at the connection. The next thing to think about, and one thing that caught me up, was that the tank full of water was f....g heavy! I just about lost my finger when it dropped on it, even though I had a good grip.

    Otherwise its all pretty straightforward and a pro can do this much faster than you can and not make mistakes like you will. They would know better whether that black stuff needs to be flushed out of the rest of the system or not too. So call a heating contractor. By the way, I paid about $70 for a new tank and it took me a total of about 3 hours to do, including first aid, plus a drive to the supplier for parts (twice).

    Minor extra note. After this my pressure relief valve continued to dribble a bit because there was dirt in it. I ended up replacing that too.
  • water in basement

    not a pro, or anything near one. Woke up this morning and basement had lots of water by our heater/AC system and boiler. The boiler pressure release valve was dry. So it had to be coming from the Heater/AC. There is a PVC tube running from the heater into a drainage system on the floor. Can you tell me if the heater is supposed to release water. Also, there was some sediment in the water and it was brownish, black.

    Any help will be greatly appreciated
  • PS_3
    PS_3 Member Posts: 28
    New Thread


    You might want to start a new thread with "Water in the Basement" as a title - your questions might be overlooked in this thread.
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