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steaming faster than condensate can return?

Just had a new weil-mclain EG-30 steam boiler installed. After the contractors skimmed it and had it steam for 15 min they left and called the job done until they come back in a month to check it and clean it some more.

Here is what I noticed. The next day after install I looked at the guage glass and it was completely filled with water. The boiler was cold at this point. This seemed odd so I flushed some water out to get it to the middle of the glass. I tested the boiler yesterday. Started with a cold boiler, water line at middle of gauge glass. Bumped up the thermostat to 75 to get the cycle started. Temp inside the house was 72. As the boiler started to steam the water level in the glass slowly started to drop. 15 min into the cycle it was only about 3/4 from the bottom of the gauge glass.

Does this seem to you guys like the system cannot return condensate fast enough to keep up with the steaming boiler? If so I am concerned that when the boiler starts cycling regularly during the cooler season the low water cutoff will kick in and trigger the auto feed which may overfill the boiler. I had in the contract that the boiler would be installed to manufacturer specs. In the manual it states that a reservoir may have to be piped to rectify this type of problem.

Any advise appreciated.


  • Jamie Hall
    Jamie Hall Member Posts: 20,527
    I can think of at least two

    possibilities right off the bat.  First, check your pressures.  It is possible that the pressure is high enough that the water is being backed out of the boiler into some of your returns (a dry return can hold a lot of water -- and it shouldn't have any!).  Pressure should be no more than 1.5 psi.

    The other possibility which comes to mind immediately is that one or more of the wet returns are nearly plugged with crud.  Did anyone flush them out when the new boiler was installed?

    And there may be more... but if you don't find the problem and fix it, you may well have problems with the boiler over-filling, as you mention.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Rod
    Rod Posts: 2,067
    Slow Condensate Return

    Hi- What make/model boiler did the EG30 replace?  Was your wet return piping replaced?

    - Rod
  • Bio
    Bio Member Posts: 278

    It could be also you need a lot more skimming to do, do you have a skimming port?
  • jonny23
    jonny23 Member Posts: 19

    replaced a 32yr old smith boiler that was oversized for the current radiation (multiple radiators removed over the years). all near boiler piping has been replaced. vertical systemreturn pipes at boiler have been replaced as well.
  • jonny23
    jonny23 Member Posts: 19
    this may be

    I noticed condensation in the gauge glass when I dropped the water level. I tried skimming a bit more yesterday myself because of this. The water was flowing out the tapping seemingly clear but slightly rust colored when the bucket was filled. A little oily but not much. I got the water extremely hot to the touch but not scalding. Do you think I should run the system a few more times to get more of the oils from the new piping back to the boiler and then skim some more?
  • Bio
    Bio Member Posts: 278
    edited September 2013
    More skimming

    Dont bring it to a boil, this will emulsify the water with the oils, start with a lot of cold skimimming than warm it up to about 180 F, flush everything out and start all over again, a good skim will take many hours and days
  • jonny23
    jonny23 Member Posts: 19

    sounds to me like it needs some more cleaning as a next step and then I will give it another test
  • Rod
    Rod Posts: 2,067

    Hi- You want to skim very s-l-o-w-l-y!  I had to skim my boiler 5 or 6 times over a period of several weeks as more and more crud and oil washed down out of the piping. (since then I learned to thoroughly clean the interior of new piping before installing it! :)

     Some people favor cold skimming and others doing it hot. I found the best procedure (at least for me) was to open the skim port up and add water till it is level with the skim port and then heat the water up to where it is hot but not making steam. Shut the burner off and turn on the make up water so that water is slowly trickling out of the skim port.  (with the burner running, convention currents are created in the boiler water and with burner off, the boiler water is "calmer" and I think you get a better skim this way)  After collecting  3 or 4 gallons of water, shut the skim port and adjust the water level to the design waterline in the sight glass. Be sure to then heat the boiler water to drive off dissolved oxygen in the "new" boiler water.  Watch the "bounce" in the water level when the boiler is normally operating. In a well skimmed boiler the "bounce" is minimal, if the "bounce" increases then you probably need to do another skim.

    Going back to a question Jamie asked, what is the maximum pressure your boiler reaches?  It should be 2 PSI or less. Higher pressure will back the water up beyond an acceptable level in the return piping

  • Charlie from wmass
    Charlie from wmass Member Posts: 4,244
    Do you have photos?

    Pictures help us find any glaring mistakes that can lead to this. Skimming is the first thing to try. How was the boiler sized? do you have the Radiator list with e.d.r. of each one?
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
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