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New House with steam system not behaving


Bought a house a couple of months ago, built in 1923, 2 floors full basement and about 1300 sq ft.  It has a single pipe steam system.  2 year old W-M SGO 3 oil boiler that has been converted to gas using a Carlin EZ Gas burner.

So far I have insulated all the pipes in the basement (looks like the pipes in the walls are insulated also based on what I can see), swapped out the single main vent with a Hoffman 75, and replaced all the radiator vents with various sizes Maid-o-Mist vents (using a combination of vent size selection based on size of radiator as well as distance from boiler).  I have also skimmed about 10 gallons of water out of it, though it appears there is still surging going on based on the water movement in the sight glass.

Anyway, I have fired the system up a couple of times to judge how it's working and I am seeing the following, for which I am seeking advice:

1) Surging in the sight glass... should I just keep skimming a bucket full every morning until the water is clear?  Each time I have skimmed the initial load of water is pretty black.  I don't see "oil" or film per se.  For example, I skimmed a bucket ful and let it sit overnight.  All of the black settled to the bottom as sediment and the water on top did not appear oily in any way.

2) The system takes a looong time to produce heat as compared to my last apartment with a similar system.  It probably takes about 15 minutes of firing before the header gets hot.  My other reference system would already have heating radiators by this time

3) This is one that makes me think something is wrong - the wet return piping is heating up at the same time as the riser and header.  It's almost like each end of the distribution loop is getting steam, though Im not sure how this would be possible, but it's pretty clear that the middle of the loop is heating up last while each end gets hot.  There is a hartford loop and equalizer FYI

4) I don't feel much or any air coming out of the hoffman, should I hear and be able to feel it like u can with the rad vents?  It's brand new and I was able to blow air through it before I installed it.

5) Never see evidence of pressure build up.  I just fired the system for about 40 minutes.  Burner never cut out and pressure guage never moved.  Granted it's a 30 PSI guage, though the pressurestat is set to cut in at .6lbs with about 1.3lbs differential.  Shoudl the system be able to generate 1.9lbs of pressure in 40 minutes - enough for the pressuretrol to break?

6) Radiators take a long time to get hot, and almost all of them only get about half full of steam.  The only rads that get fully hot are the little ones in the baths, all of the others stay half cold.  Again, compared to my reference system, it would have entirely hot rads in about 20 minutes.  Also, the rads are heating very unevenly.  e.g. the rad closest to the boiler and connected closest on the loop gets hot pretty fast, but the one farthest away on the second floor was just getting warm by the end of the 40 minute firing.  This slow to heat radiator currently has a #C vent on it thinking I just had a lot of air to vent out, but changing out the original #6 for the #C has made zero difference.

Suggestions welcome!  I have really enjoyed reading this forum and hope you guys can help me out



  • icesailoricesailor Member Posts: 7,265
    Slow Steamer:

    As usual, that doesn't seem to be quite what Weil-McLain had in mind when they put the suggested piping drawings in the installation manuals.

    "Don't need no stinkin' instructions to pipe this. I've been doing it like this all my life. I've never had a problem with a hot water boiler. It needs a circulator"
  • JeffBrownJeffBrown Member Posts: 67
    not sure I understand what you wrote

    is there something terribly wrong with the piping?  It looks pretty "standard" to me - main starts higher, ends lower;  there is a hartford loop and an equalizer.  I would say the way the riser sort of snakes up is a bit odd but generally it seems about right no?
  • JeffBrownJeffBrown Member Posts: 67
    compared pipe setup to installation manual

    the near boiler piping is pretty much exactly what W-M indicates in the manual.

    Condensate return connects in 2" below the 26 7/8" water line, more than 24" between water line and header, swing joints installed exactly the same as manual diagram, reducing elbow and smaller size pipe for equalizer.

    The only thing that doesn't jive is that my header slopes down slightly toward the equalizer, and the steam supply pipe from the header to the loop/main isn't a straight pipe, it's a little snaked up almost like a half spring...
  • Dave in QCADave in QCA Member Posts: 1,660
    Some more data is needed

    Before you spend a lot of time guessing, we need some additional information.

    1. What is the total EDR of your radiators.  If you don't have the information necessary to figure that out, I'll post a guide that will help.

    2.  What are the ratings on your boiler?

    3.  What is your present firing rate?  Make sure nothing else is burning gas and then clock your gas meter with your boiler firing.

    First observations indicate two things.  The boiler you had at a previous house was probably oversized a bit.  This boiler is likely undersized, or the firing rate is set lower than the design of the boiler. 
    Dave in Quad Cities, America
    Weil-McLain 680 with Riello 2-stage burner, December 2012. Firing rate=375MBH Low, 690MBH Hi.
    System = Early Dunham 2-pipe Vacuo-Vapor (inlet and outlet both at bottom of radiators) Traps are Dunham #2 rebuilt w. Barnes-Jones Cage Units, Dunham-Bush 1E, Mepco 1E, and Armstrong TS-2. All valves haveTunstall orifices sized at 8 oz.
    Current connected load EDR= 1,259 sq ft, Original system EDR = 2,100 sq ft Vaporstat, 13 oz cutout, 4 oz cutin - Temp. control Tekmar 279.
  • Mark NMark N Member Posts: 1,035

    I'm just a homeowner like you . The water looks very dirty I would cold skim that boiler for hours. If that doesn't work you might need to clean the boiler using Weil-McLain instructions. How much radiation is connected to the boiler. Do you know if the gas burner is firing at the proper rate. If it is under fired it might take for ever to heat the system up and never build pressure. Clock the burner when its running to get an idea if your firing at the proper rater. Make sure no other gas appliances are running when doing this.
  • RodRod Posts: 2,067
    No Steam Pressure

    Hi Jeff-  Others have already suggested the most likely possibilites. I gather that since you bought the house just several months ago you have no idea how the system performed in the past ?

    It appears that you aren't making steam.  As other have mentioned the first thing to do would be to clock the burner. This will give us an idea of whether the burner is fired at an appropriate rate for the boiler.  We want to see if the clocked BTUs come close to what the input numbers are on the manufacturing data plate for that model.

    Here's a link that explains how to clock a burner:

           After doing that I would consider flushing the boiler by filling and emptying it several times.  On the final fill be sure to then heat the water up as this drives off any dissolved oxygen which can be very corrosive to your boiler. 

          I don't see anything really unusual in your piping other than I would change the pigtail orientation leading the gauge and pressuretrol. You want the pigtail and gauges/controls on the vertical so water will drain away from them. control and gauges, I would also move the gauge(s) and control higher so they are above  the skim port water level. (see attached picture with includes a low pressure gauge.

    - Rod
  • JeffBrownJeffBrown Member Posts: 67
    more data

    argh I wrote up a lengthy response and then lost it.

    Here's what I've determined

    206 sq ft of radiator or 49390btu/hr output (add 33% for pipes and you get 274 sq ft and 65688btu/hr

    Boiler is rated up to 114,000 btu output and 358 sq ft of steam.  This is a good start

    Burner is rated bewteen 50-250,000btu/hr output depending on the orifice installed.  I cannot verify the orifice but the tech that installed the burner wrote "orifice 7/32" on the service tag.  Carlin doesn't list such a size but it is in between two sizes they do have so it's somewhere between 75-100,000btu/hr.  This is also good!

    I clocked the gas meeter and determined that it took 71 sec to use 2 cu feet of gas.  This calculates to 101.4 cu feet in 1 hour.  multiply by 1020 and you get 103,436btu/hr.  This confirms the 7/32 orifice size unless I am screwing up the math!

    So unless I have this totally wrong, the boiler, burner, and radiator/piping sizes and capacities all seem to correct.  If anything, the output of the burner is actually oversized for the amount of radiation I have and the amount of steam I need, no?  The boiler has a tankless coil installed so perhaps you need to size things up in order to provide sufficient btu to generate you steam and hot water simultaneously?
  • JStarJStar Member Posts: 2,668

    It all looks like it's piped correctly, nice big Hoffman main vent. I would have somebody do a draft and combustion test to fine tune it for more efficient firing,
    - Joe Starosielec
    [email protected]
  • Steam test

    Can you open up the skimming leg, and fire the boiler while standing next to the circuit breaker for the boiler ready to cut the power when you see steam? Record the time it takes for steam to come out of the skimmer. Then close up the skimming leg, and remove the main vent, performing the same test.

    Position yourself far enough from the steam, so you are not burnt. If the steam to vent test is longer than the steam to skimming leg test, then either there is a sag in the main which makes it difficult for the air to get out, or the main vent needs cleaning/replacing/enlarging.--NBC
  • JeffBrownJeffBrown Member Posts: 67
    here's what I did try

    I fired the system up and felt the header and main for heat so I could sort of "follow" the steam as it travelled around the main to the return.  Once steam starts travelling into the main it takes about 2 minutes for the steam to get to the main vent at the end of the line.  This is with a single Hoffman 75, so I think I'll add another which should halve the time theoretically.
  • Doubling the main venting

    I think you can get a gorton#2 for the same price and will have more capacity, so choose that one. You may still have a sag in the line problem if that additional venting doesn't fix the problem.--NBC
  • Hap_HazzardHap_Hazzard Member Posts: 1,349

    I use a digital meat thermometer to sense the temperature in steam pipes. You can stick the probe under the insulation, and you can set the alarm if you just want to know when the steam reaches a certain point in the piping. Some guys like to use those infrared remote thermometers instead. Both techniques are better than putting your hand on the pipe.
    1983(?) Peerless G-561-W-S
    3" drop header, CG400-1090, VXT-24
  • JeffBrownJeffBrown Member Posts: 67
    funny you should mention that

    because I have one of those laser thermometer guns that I bought when working on the central AC reason I couldn't also use it to get the temp of the pipes!  Thanks, I was getting sick of burned fingers :)
  • JeffBrownJeffBrown Member Posts: 67
    funny you should mention that

    because I have one of those laser thermometer guns that I bought when working on the central AC reason I couldn't also use it to get the temp of the pipes!  Thanks, I was getting sick of burned fingers :)
  • kcoppkcopp Member Posts: 2,744
    edited September 2012
    You should not...

    add the 1.33 pick up factor to the EDR...  that is figured in already.... this especially since you are insulated well. You said you clocked the meter and get 103k? Looks to me as if the boiler is over sized... and maybe over fired. Skimming need more work too. Is the equalizer 1 1/2" or 1 1/4".. 1.5" is  the standard.
  • JeffBrownJeffBrown Member Posts: 67
    pipe size

    i think the equalizer is actually 2".  Not sure I have the pipe size thing quite down yet...but the circumfrence of the equalizer pipe is 7.5" which I believe ends up as a 2.38 diameter, or a 2" NPS?
  • JStarJStar Member Posts: 2,668
    edited September 2012

    I'm still leaning towards a possible high draft condition. In the one picture, it looks like the draft control damper is slammed right up against the return pipe. Not much room for movement or service.

    If the damper is closed, the draft will higher in the boiler. Maybe too high. When the draft is too high, it will draw more heat out of the boiler and out to the chimney. That could explain the unusually long run times.

    Shoot your laser thermometer on the vent connections before and after the draft control. See what the temperatures are with the damper open and closed.
    - Joe Starosielec
    [email protected]
  • JeffBrownJeffBrown Member Posts: 67
    is this normal?

    I'm doing more skimming today....Attached is a pic of what is coming out of the skim port when I remove the plug and it drains about 8 oz of liquid.  I assume this water is getting into my skim port pipes via the motion of the boiling water flinging itself into the skim port.  It's not oily and greasy, but as you can see the water is black and has "chunks" in it.  These black chunks are like flakes of something and they disintegrate when I rub them between 2 fingers.  These chunks also exist in the return piping because I found some inside the pipe where the main vent is installed (as in I stuck my finger in the nipple hole just to see what was up)

    Is this just corrosion?  Is this usual?  I have also noticed that the water in the sight glass is completely clear unless the system is running and the water becomes brown.
  • JeffBrownJeffBrown Member Posts: 67
    it's not as bad as it looks

    the return is close by but it's servicable.  Here's some pics.  The weight is all the way to the out setting, which I assume makes the damper heavier and causes it to stay closed unless there is a signifncant draft inside the vent?
  • JStarJStar Member Posts: 2,668
    edited September 2012

    Picture was misleading.

    There should be markings 2,4.6,8. Those are draft settings. If it's maxed out at 8, that may be too high. You can adjust it down to 4, but it'll be impossible to tell the real draft numbers and affect on the system without doing a combustion test.


    I see that it is set at about the 2 marking, so that "shouldn't" need to be adjusted.
    - Joe Starosielec
    [email protected]
  • JeffBrownJeffBrown Member Posts: 67
    I'll leave that to the pros

    I'll leave that to the pros!
  • kcoppkcopp Member Posts: 2,744
    Wrong damper....

    on gas that should be a double acting type w/ a thermal cut out/ spill switch... the one on there for oil.
  • kcoppkcopp Member Posts: 2,744
    how much are you draining?

    I actually like to just have one straight pipe out of the boiler to a 5 gallon bucket.... Then open the fill valve just enough to trickle it for a few hours.... yes hours. It was prob never done. Put some of that in a saucepan and boil it.... if it foams there is oil in it.
  • JeffBrownJeffBrown Member Posts: 67
    even with my setup?

    my setup is an oil boiler converted to has using a carlin ez gas would this setup use an oil damper or gas damper
  • kcoppkcopp Member Posts: 2,744
    double acting ...

    needed to be switched at conversion....
  • JStarJStar Member Posts: 2,668

    It does need to be a double swing damper for safer operation, but the boiler should still run the same.

    You can try to prop the damper open a little and see how that affects the operation. Checking the flue temperature can lead you in the right direction.
    - Joe Starosielec
    [email protected]
  • JeffBrownJeffBrown Member Posts: 67
    how ive been doing it

    ive been skimming about 10 gallons at a time and have done this oh 5-6 times, so about 50 gallons so far.

    To clarify my previous statement, due to the way the installer installed the skim piping, water builds up against the plug at the end of the pipe - you will see what I mean if u look at the pics above.  When I remove the plug to skim, about 8oz of black water and gunks comes out, and then I turn on the water feed to a medium trickle and fill/empty a 5 gallon bucket a couple of times.

    When I'm done I hook up a hose to one of the drains and drain the boiler till the water level is back to the correct level (per the mark behind the sight glass)
  • kcoppkcopp Member Posts: 2,744
    sounds to....

    me that you could use a hands on consult... where are you located?
  • Hap_HazzardHap_Hazzard Member Posts: 1,349
    Actually it's 2.375

    But it's hard to measure circumference accurately. :-)
    1983(?) Peerless G-561-W-S
    3" drop header, CG400-1090, VXT-24
  • Paul48Paul48 Member Posts: 4,228

    like oil in the sight glass,it appears to be seperated? Need a steam pro to weigh in on looping a main back to the boiler and putting a main vent right over the boiler, like that one. Steamhead?
  • JeffBrownJeffBrown Member Posts: 67
    Somerville, MA (just north of Boston)

    Somerville, MA (just north of Boston)
  • kcoppkcopp Member Posts: 2,744
    I'm i NH...

    about an hour north of you... less traffic. Did you look in  find a contractor at the top?
  • JeffBrownJeffBrown Member Posts: 67
    Yes I did

    made a few calls, waiting for callbacks from 3 contractors to discuss
  • David NadleDavid Nadle Member Posts: 624
    Improving your skim setup.

    I think a lot of homeowners on the wall would be envious of your skim setup. That black gunk accumulating looks like the same stuff that would come out a drain for the first few quarts, i.e. normal.

    I think you could improve things a little by removing the vertical nipple and plugging the bottom of the elbow instead, then tilting the skim pipe ever so slightly upward so it naturally drains back to the boiler. This will eliminate the shot of sludge every time you open the plug. You can screw the nipple (or even better, a flexible hose that reaches down to the bucket) temporarily whenever you skim.

    Try to open the feed as little as possible from the start. Don't open it wide until it spills out then turn it down. It should take hours to fill a 5 gallon bucket if you're doing it right. Repeat until the sight glass looks good. The good news is you have to do this even if it later turns out to be a burner issue.

    It's common for 30 psi gauges to not register anything, and if your radiators are still filling then their vents are open and you should be operating nowhere near 2 psi. If you want to validate your pressure you can build a manometer out of flexible tubing and a hose barb for about $10. I think if you serach the Wall for manometer you'll find some info.
  • JeffBrownJeffBrown Member Posts: 67
    thanks for the suggestion

    though your response makes me wonder why is it so important to do the skimming so slowly?  Thinking of the boiler as a glass of water that we are feeding additional water into from the bottom, the water on top is always going to spill over the top first, taking the oil/gunk with it.  How is it significantly different on a boiler?  I don't open the feeder valve all the way...maybe a quarter open, takes maybe 8 minutes to fill 5 gallons....

    I bought a 0-5psi gauge so I will plumb that in there so see if we are getting any pressure. 
  • David NadleDavid Nadle Member Posts: 624
    Take it slow

    The idea behind skimming slowly from a cold boiler is you don't want to disturb the surface of the water and you don't want oil clinging to the sides of the boiler instead of sitting on the surface.

    Ideally, the trickle would be so slow that a pure layer of oil and no water would spill from the skimmer until all the oil was gone, instead of a lot of water spilling out and carrying a little oil with it.
  • JeffBrownJeffBrown Member Posts: 67
    More Data After some changes

    OK, so I now have 2 hoffman 75's at the end of my main, and Maid o Mist #4s on ALL radiators.  Main is about 25' long and the pipe starts at 2.5 and reduces to 2 about 1/3 of the way around.  Here's what happens:

    Burner ignites - 0 min

    Steam enters main - 7 min

    Main is completely filled w steam - 10:40 min

    Radiators really start generating a lot of heat - 30 min

    I must admit, changing all the rads to #4 really seems to have evened things out and I'm sure the additional 75 is helping with that as well.

    My 2 rads farthest from the boiler continue to underperform compared to the rest, however.  These rads are on the second floor, share a single steam pipe, and are also connected to the main the 2nd to the end.  I think all these issues are contributing to the problem.  I will change out the #4's in these 2 rads for #5's and we'll see how that changes things.

    I also noticed that the worse of the 2 rads discussed above had, for about 2 minutes, the SLIGHTEST hammering, barely detectable but there if you are looking for it.  No hammering anywhere else.  The feeder pipe for these 2 rads rises up through an outside wall to the second floor and then tee's off to the left and right.  The left rad is about 3ft from the tee while the right one (the worst one) is about 10 feet from the tee.  I assume the hammering may indicate a slight sag in the pipe feeding that rad, though there's probably nothing I can do about this without opening up the wall.

    Should I add additional main venting?  What about my 2 problem rads?  How do my timing results jive with what is normal or correct?  Should the system have reached .5psi after 30 min?  The boiler never shutdown

    Thanks again!
  • JStarJStar Member Posts: 2,668
    edited October 2012
    Second floor

    The connection for the second floor radiators looks like a capital T? That could be part of the hammering problem. Do you know the EDR of the two radiators and the size of the pipe? You can also vent the common pipe as if it were a main.
    - Joe Starosielec
    [email protected]
  • JeffBrownJeffBrown Member Posts: 67
    i dont know for sure

    that it looks like a T since everything in is the wall.  I do know that there is a single supply pipe that services these two rads which are against the same wall I guess I dont know for sure what the layout is, nor will I without removing some plaster.

    Rads are 18 and 20 EDR....pipe size, good question, shoulda measured before I covered everything in insulation :)  I would estimate that it's 2" based on what is used elsewhere
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