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Boiler Water Still Dirty

one thing i have done, which has moderated the dirty water problem : i placed one of those long strong magnetic strips [such as would hold up tools when mounted on a wall] along the wet return. i think that all the rust particles have been stuck there.
when you next drain any water out of the boiler, catch some in a saucepan. next put it into a glass bottle.tape a good magnet to the bottle under the waterline and shake it up. you will find a big clump stuck to the magnetic spot when it has settled! a gordon's gin bottle with straight sides is ideal for this experiment.--nbc


  • FJL
    FJL Member Posts: 354
    Dirty Boiler Water

    After my last flushing of the boiler about ten days ago, the water in the sight glass was dirty, but then settled. I had checked the water a couple of times since then and the sight glass water was clear. Just checked now, while the boiler is running, and the water is halfway up the sight glass, and all of it is dirty. That can't be common, can it? I guess when the boiler fires, it upsets sediment. I will flush again and see if it helps. What side effects occur if the water stays dirty or keeps getting dirty, even after I flush it? This boiler is only in its second heating season. This is a one pipe steam, gas fired, boiler.

  • I see a certain amount of rusty water every time I test my LWCO or draw off water from the bottom of the boiler . . . it runs rusty for a few seconds and then clears up. The sight glass shows a little rust afterward, but clears up quickly as things settle. I thought that was pretty normal. My boiler is seven years old. Maybe it was neglected for the first six years before we moved in.

    I'm interested in what the pros have to say.
  • Steve Garson_6
    Steve Garson_6 Member Posts: 35

    Perfectly normal. Steam pipes and radiators have some rust inside them since they are exposed to air. Every time the condensate comes back to the boiler, so does some rust.

    If the water has some faint rust but you can still see through the water, don't worry about it. If it's darker, a complete draining and refill of the boiler might be in order. But add water gradually so you don't crack the boiler. Then run the boiler to a full boil for a while to help get the oxygen out of the water. You shouldn't have to do this more than once every several years.
  • FJL
    FJL Member Posts: 354
    Not Faint Rust

    I don't think I'd call what I saw faint rust. Water was a little dirtier than that. Not see thru. Funny thing is, though, this is the first time I've seen it dirty, even when running, aside from when it has been flushed.
  • FJL
    FJL Member Posts: 354
    Water Clear When Boiler Off . . .

    I went down to the boiler about 30 minutes after the set back kicked in, so the boiler had been off for at least that long. The water in the sight glass was clear. I decided to flush it a bit, and some dirty water flushed out and also filled the sight glass. I didn't flush for very long, and the sight glass was dirty when I left.

    Is it normal for the boiler water to be dirty when it runs and settle when it turns off for a while? And should I wait a certain amount of time for the boiler to cool down after running to flush it or does it not really matter?
  • flushing

    when you say flushing the boiler, what exactly are you doing? here are the boiler buzz words, and their definition, as i understand them:

    skimming- the controlled release of oil and grease from the surface of the boiler waterline [through a specially installed port].the purpose is to make better boiling and dry steam.usually this must be done after first installation, or after any major reping work.

    flushing- the cold draining of all the water in the boiler and returns.subsequently the boiler is refilled.sometimes cleaners are added to assist in dislodging sediment at the bottom.

    blowing down-the opening of the boiler drain valve during steaming on a regular basis to blow out the sediment collecting in the bottom of the boiler.also the LWCO must be blown down to remove sediment which could interfere with the mechanism.as we know the sediment swirls around during boiling, so is this really effective?

    hope this clears up some boiler terminology.--nbc

  • SusanC
    SusanC Member Posts: 106
    Question re: blowing down boiler drain valve

    If, as you say, sediment swirls during boiling, why would one blow down boiler drain valve while steaming rather than after 1/2 hour or so when the sediment would have settled?
  • FJL
    FJL Member Posts: 354
    Flushing . . .

    Maybe the more accurate term is draining? I open the valve, on what I guess is the low water cut off, to release water until the water runs clear. The purpose of this, as I understand it, is to get rid of the dirty water and sediment at the bottom of the boiler so that the gunk is not swirling around in the water when the boiler makes steam. I assume that steam from clean water is better than steam from dirty water.
  • SusanC
    SusanC Member Posts: 106
    Question to nicholas bonham-carter

    My question concerns draining or blowing down from the bottom of the boiler - I have a set-up that lets me drain from there. (As an aside, incidentally, having learned from the previous boilers problems, I can also drain or flush from other strategic locations.)

    Anyway my question for NBC is:

    If, as you say, sediment swirls during boiling, why would one blow down boiler drain valve (at bottom of boiler) while steaming rather than after 1/2 hour or so when the sediment would have settled?

  • David Nadle
    David Nadle Member Posts: 624
    Mind if I take a whack at it?

    Blowing down under pressure would help move out some of the real heavy stuff on the bottom.
  • why indeed?

    why not do it both ways: a little blow-down while steaming; and then anoyher while the boiler is at rest.
    in the case of the mcdonell-miller 67 lwco, there is a float which must not become immobilised, and stuck with sediment. it's blown down more frequently, to avoid dry-firing.
    dan's book goes into some detail on this--nbc
  • SusanC
    SusanC Member Posts: 106
    Thanks and , incidentally, I know about LWC

    I appreciate the replies from both of you. I know why one blows down the LWC-O while steaming; that's why I specified drain at the bottom of the boiler. Current boiler has probe which gets serviced annually along with everything else. Previous boiler had LWC and I religiously (without going overboard) flushed that.

    As far as drain located at bottom of boiler, I'm not fond of opening drains on steaming boilers, which was the main reason I asked the question after seeing the NBC definitions and suggestions.
  • FJL
    FJL Member Posts: 354
    So I guess . . .

    I should make sure to drain the boiler regularly to get rid of as much gunk that is in the pipes and making its way into the boiler? Is there a set amount of time I should wait after it has turned off to start draining?
This discussion has been closed.