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glass gauge level too high?

We've lived in our NYC home with a one-pipe steam heat system for decades, with the same hard working boiler, with various issues over the years, much helped when I started reading Dan's books and following his guidance. This year I'm noticing that the water level in the gauge glass is well higher than in prior years. Usually it is about two thirds up the gauge; now it is all the way at or over the top, only visible briefly when I flush the blow-off valve which I do weekly. My service contractor tells me this is not a problem, and also not a sign of any problem, though "the boiler will have to work harder to make steam" and I "might want to lower the level." He tells me I can do this myself through the valve at the bottom of the boiler.

Before I do this I would like to double check. First, though I haven't fully started up the system yet this year, I'm noticing that the radiators are heating more unevenly than before, throughout the house, and making more noise--possibly related? or just the air vents? Second, I really don't want to have the boiler working any harder than it needs to, or spend any more money on gas to heat the water than I need to. So I'm tempted to go ahead and drain off some water, and see if this helps. On the other hand, I don't want to do anything I'll regret by trying to lower the water level through the drain (even though I've seen the plumber do this when making repairs to a corroded return pipe).


  • JStar
    JStar Member Posts: 2,752

    That's not normal!

    The water feed shut off valve may be leaking into the boiler. Do you have a tankless coil as well? You want to eliminate this problem as soon as possible. The water should be about half way up the sight glass.
  • BobC
    BobC Member Posts: 5,477
    The question is

    Where did the water come from? Does the boiler have an automatic water feeder? If so some water may be leaking by it.

    If you have a coil in the boiler for domestic hot water that could have a pinhole leak that is slowly adding water to the boiler.

    The water level should not be high, drain it down to the regular water level and watch it carefully to see if it starts to creep back up. Adding excess fresh water to steam boilers shortens their life, best to find out why and fix it.

    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
  • years_of_steam
    years_of_steam Member Posts: 26
    yes I have a hot water coil in the boiler

    And about 20 years ago or more, had to replace it.... at that time the signal was surging in the glass gauge... (if I remember right)...

    And I have an automatic feed. So I guess it could be either or both?

    Since you are both so quick to respond, I have another question. Over the last two or three years it seems I need a new thermocouple every year, sometimes more than once. They just burn out. I have a service contract so the service call is included, but I get charged a quite lot for the thermocouple. Any comment? Or is this outside the scope of questions for this wall?
  • nicholas bonham-carter
    nicholas bonham-carter Member Posts: 8,576
    edited October 2012
    neither more nor less

    go ahead and lower the level, and then let's try to find out where the extra water came from. drain down while the boiler is switched off, and put a clothes pin on the rod next to the site glass, marking the midpoint level you have drained it down to.

    check the water level every few days  [after the boiler has not run for an hour[. this will tell you if you have a leak in the system, or if water is leaking into the system from an auto-fill, or leaking hot water coil. make sure the valve to any water feeder is turned off during the test period, and test your lwco to make sure it works.

    one cause of excess water can be excess pressure forcing water out of the boiler into the returns, and activating the water-feeder, [if you are so unfortunate to have one!]. after you have run for a week, you will see whether the waterline is lower or higher. we will have more advice for you after those results,--nbc

    here is the thermocouple thread:

  • JStar
    JStar Member Posts: 2,752

    Thermocouples typically burn out prematurely due to pilot issues. The flame could be too strong, or cover too much of the thermocouple.
  • years_of_steam
    years_of_steam Member Posts: 26
    thanks for the input

    This is very helpful, I will go boldly forward as a fairly handy homeowner but definitely not a pro. I probably will not try to shut off the valve to the automatic feed just yet (unless you say I need to for sure) as the service fellow who was here started down that path and found it to be very tight (did I mention it's old?) and I don't want to break it. (I've done that before with my water lines.) But I will do it while the boiler is off and monitor closely what happens.

    And I will keep you posted. Very impressed to get such quick responses at this hour from folks who show up at work at the crack of dawn.

    PS is it OK to ask what the ballpark cost of a thermocouple is?
  • Rod
    Rod Posts: 2,067

    Ah.... One of the board rules is that we don't discuss pricing. You might try Pex Supply on the internet if you need an idea as to the approximate cost..

    - Rod
  • nicholas bonham-carter
    nicholas bonham-carter Member Posts: 8,576
    Freeing a stuck valve

    Most of the time a stuck valve can be loosened by unscrewing the packing nut of the valve. This is right under the handle, and is compressing some graphite string around the valve stem. Use an open end or crescent wrench and turn it enough to reduce the pressure on the stem. If all goes well, the handle will now move with hand force.

    The water-feeder really needs to be disconnected from the water supply, so you know whether more water comes into the boiler from another source, (hot water coil).

    Just in case, you can turn off the main water valve while you do this, at a time when hardware shops are open.--NBC
  • years_of_steam
    years_of_steam Member Posts: 26
    Thanks for your help

    Just to follow up, I did lower the water in the boiler, and since then it's been holding pretty steady.... it came up about a half inch over a week or two, and when I flush the blow-off valve weekly it can go up another inch or so for a little bit, but it is staying pretty steady within that range.

    I'm thinking I can just monitor it for a while?
  • Hap_Hazzard
    Hap_Hazzard Member Posts: 2,846

    You can probably find prices on Home Depot and/or Lowes and compare to Pex Supply or Amazon. The home stores may not have the best prices, but they have the advantage of being local and open all hours, because thermocouples generally don't give notice. Of course, you can always buy one ahead and leave it hanging on the wall in your boiler room.
    Just another DIYer | King of Prussia, PA
    1983(?) Peerless G-561-W-S | 3" drop header, CG400-1090, VXT-24
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