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water level issue

JM_2 Member Posts: 108
Is it possible for an undersized boiler to run long enough that it triggers the auto fill feature, resulting in an overfull condition when the boiler cools down.

I have a friend who recently removed all the asbestos insulation from the basement pipes. ( I think the new radiant load presented by the un- insulated pipes has the net effect of making a barely right sized boiler, now undersized ) the recent cold snap here in new England found him with an awful banging in the basement.  when he went down he found the sight glass full of water, after removing what he says is about 10 gals of water the banging stopped.

Is the removed insulation in concert with the auto fill the likely culprit?

Thank you.


  • the importance of insulation

    it's not just a pretty face-the insulation-it's a necessity. it is best to use,one inch  fiberglass pipe insulation, sized for the diameter, however, fiberglass batts wrapped around the pipes will get you through the winter. do it soon before the water-hammer shakes up the pipes too much!

    one more cause of temporary low waterline is high pressure forcing water to back up in the returns, triggering the "over-fill"

    in addition turn off that auto-fill, so you can see whether you have a leak in the pipes somewhere.

    get a copy of "the lost art of steam heating" at the shop above, and learn about some other things not to do.--nbc
  • Jamie Hall
    Jamie Hall Member Posts: 22,912

    good grief.  The insulation is essential.  Remember, the dead men didn't go in much for frills.  My guess is that the removed insulation is probably the number one cause of your problems -- although as NBC says, you should check the pressure as well.  I doubt very much that the autofill was anything more than an accessory after the fact; after the lack of insulation caused most of the steam to condense in the mains, where it doesn't belong, and bang around like the hammers, the autofill just did it's job of protecting the boiler.  Then when the boiler shut off, it just natrually was overfilled.

    You are quite right too, in that what was previously a right-sized boiler is now between 30 and 50 percent undersized.

    Insulation is not expensive.  Lack of it is.  I respectfully suggest that you get some, if possible this week, and get it on there -- pronto.

    From what I read on the weather, you have about a week and a half grace...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • jpf321
    jpf321 Member Posts: 1,568
    edited December 2009
    insulation or bigger pipes..

    i came across this article one day recently .. and I think this best illustrates the need for cozy pipes .. (assuming he speaks the truth)

       "If the steam pipes are uninsulated, they are too small. The original installing

    company had to decide whether to insulate the pipes, or increase the

    size by TWO pipe sizes. They NEVER chose to increase the pipe size. It

    will be easier for you to reinsulate your existing piping than it would

    be to increase all of the mains two pipe sizes." -- Noel Murdough

    There is also this reference from one of the actual Dead Men, William Monroe, in his 1902 book Steam Heating and Ventilation:

    "Pipe coverings. All the piping connections should, as far as.

    possible, be covered with some kind of non-conducting pipe covering,

    of which there are innumerable varieties made. In some

    cases risers and other pipes are left uncovered so as to utilize the heating

    effect, but the disadvantage of this is that heat is given

    out from such pipes whether it is wanted or not, and it is much

    better practice to cover the risers and depend on the radiators,

    for heating. One of the greatest sources of fuel waste is found

    in uncovered mains in basements of buildings where heat is nothing

    but an inconvenience, and in order to dispel it in moderate

    weather windows are opened, which greatly increase the wasteful

    condensation. A good pipe covering will save from 65 to 80 per

    cent, of the heat which would ordinarily be wasted from the pipes.

    Coverings of which 85 per cent, is carbonate of magnesia, certain

    molded forms of pure asbestos fiber, and molded forms of mineral

    wool are the best kinds of protection for steam pipes to reduce

    condensation. Some coverings which show very good results when

    new, deteriorate rapidly, due to the charring effect of the pipes and

    to disintegration."
    1-pipe Homeowner - Queens, NYC

    NEW: SlantFin Intrepid TR-30 + Tankless + Riello 40-F5 @ 0.85gph | OLD: Fitzgibbons 402 boiler + Beckett "SR" Oil Gun @ 1.75gph

    installed: 0-20oz/si gauge | vaporstat | hour-meter | gortons on all rads | 1pc G#2 + 1pc G#1 on each of 2 mains

    Connected EDR load: 371 sf venting load: 2.95cfm vent capacity: 4.62cfm
    my NEW system pics | my OLD system pics
  • JM_2
    JM_2 Member Posts: 108
    pressure is normal

    pressure troll is normal. 1/2 cut in diff. 1. The system has some unusual near boiler piping, Bull T heade, no real equalizer, a newish domestic HW tank fed from condensate but returned up high about at the water line not down low.

    The main thing is it ran quiet until he removed the insulation 
  • "hiding" condensate

    after you have insulated the pipes ,[apparently the straw which broke the camel's back!],  investigate the following.

    if there is a horizontal pipe close to waterline level, that can hide a lot of condensate, as the pressure pushes up the water into the returns. any wet returns should always drop to the floor for any horizontal runs.

    until you have a good low-pressure gauge, you will never be sure as to what your pressure is! water rises 1 3/4 inches for every ounce of pressure, so if you are at 3 psi your water could have been temporarily shoved up into the returns, and is trying to fill the horizontal. the result-the auto-fill thinks the boiler is low on water and adds more; however in between cycles, the water all comes back, flooding the boiler. turn off the auto-fill, and see if all the water comes back.--nbc
  • Jamie Hall
    Jamie Hall Member Posts: 22,912
    You've answered your own question...

    "It ran quiet until he removed the insulation".  There you are... it doesn't really matter what you are working on; if it ran OK before you did something, and not so well afterwards, undo what you did for starters.

    Get insulation back on, and then worry about some of the other oddities.  And note one of my other old saws: "if it ain't broke, don't fix it".

    Incidentally, jpf321's quote will repay listening to.  I happen to have met Noel, and believe me he is one of the very best brains in this business.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • JM_2
    JM_2 Member Posts: 108
    there is one thing I left out

    The homeowner had finished room built in the basement. In order to do this they had a plumbing Co move some of the steam pipes. I also notice some brown stuff floating on the water in the site glass. and when I drained off some water I can see a sheen on top. I think The boiler needs a good cold skimming as well as the insulation put back.
  • Jamie Hall
    Jamie Hall Member Posts: 22,912

    I hope the plumbing company moved the pipes laterally only, and not up or down...

    Sounds like you do need to skim that boiler, too.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
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