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"I'd like to see them make "

Anyone old enough to remember either Popular Mechanics, or PopularScience magazines will remember this collumn as a regular feature.

I would like to have a self-skimming arangement on a new or heavily re-piped boiler.

Surely the oily water could be concentrated in the skimming port (as it splashes around) with a drop down connection to the return. Thus the oily residue would float in this piping, isolated from the main boiler water, and able to be drained away occasionally, without losing large quantities of water.

Anyone else have any desires for some improving change or gadget?--NBC


  • SWEISWEI Member Posts: 7,356
    somehow I'm envisioning

    One of those old school pool filter inlets, with the little flapping door...
  • kcoppkcopp Member Posts: 2,775
    a condensate....

    pump w/ a neutralizer all in one.
  • Jean-David BeyerJean-David Beyer Member Posts: 2,532
    a condensate.... pump w/ a neutralizer all in one.

    I am not sure about that. One of them will fail first, and you will have to throw out the other. Like my damned color ink cartridges for my printer. I run out of one color and must toss the other two, harming my wallet and the environment at the same time.

    I suppose the motor or pump bearings will go first. Unless the plastic is wrong, I cannot imagine the neutralizer would fail -- just need new marble chips from time to time.
  • ChrisJChrisJ Member Posts: 8,631
    edited August 2012

    I have to be honest, being skimming is only done when oil / crap has been introduced into the system due to repairs its not really a high item on my list.

    I'd much rather see them produce a quality 3 pass steam boiler for natural gas / propane!  Maybe even throw something extra in like a condensate preheater via exhaust too.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment

    Steam system pictures
    Central air project pictures
  • Mark EathertonMark Eatherton Member Posts: 5,584
    The automatic super skimmer...

    It's actually here, you just didn't realize it ;-)

    The process of skimming a steam boiler is essentially a cooling process with a need for extreme control no?

    Essentially, you need to control the flow of water exactly to maintain a given "rise" is water temperature across the heat source (steam boiler), while also maintaining a working high limit in case the water flow is interrupted.

    These items are available OFF SHELF, and only need installation and programming to make them work.

    So you use the tekmar floating action set point controller, programmed up for cooling, and connect that to a motorized, slow opening zone valve, like a White Rodgers on the down stream side of the PRV serving the make up to the boiler. It will require a little bit of calculation as it pertains to the opening/closing time of the W/R valve, but only has to be done once.

    Then adjust the set point to your desired discharge water temperature, set a sensor in the effluent, and let her rip. If the flow of water is interrupted, and the water temperature starts getting REAL high, you will want a simple set point controller set as a thermal high limit to avoid getting steam.

    There you have it, an Automatic Super Skimmer. ;-)

    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • ChrisJChrisJ Member Posts: 8,631


    I believe what he wants is a system which automatically knows when to skim the boiler and performs the functions automatically without any interaction from someone.  When you skim a steam boiler your rolling the oils off of the top of the water, often using heat to keep the water hot though others prefer a cold skim.

    I skimmed my boiler 6 times before it was clean enough for me and I found the hotter I got it without boiling, the better she skimmed.  I'm fairly certain the reason it took me 6 times was a combination of learning how to skim and the use of too much dope by a dope (me).
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment

    Steam system pictures
    Central air project pictures
  • nicholas bonham-carternicholas bonham-carter Member Posts: 6,540

    I am looking for a piping arrangement which will separate the oily water into a pipe connected into the returns. The oil will stay in the upper part of the pipe, and could be drained off periodically by a valve set slightly below the waterline height.

    My theory is that the oily water (after installation), will splash into this skimming leg running down from the skimming port. As it will be trapped there, floating at the top, at waterline height, it can be drained easily. This would relieve many people who otherwise would have to sit beside the boiler, beer in hand waiting several hours or days for the oils to be drained off the surface.

    The time saved will enable them to do other things, such as cleaning out the garage/attic; laundry;etc.--NBC
  • ChrisJChrisJ Member Posts: 8,631
    waiting while skimming

    I've actually fallen asleep while skimming!
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment

    Steam system pictures
    Central air project pictures
  • BobCBobC Member Posts: 4,457
    It's an art

    If you don't drink or you drink to little you might just fall asleep.

    If you drink just the right amount you will have to use the john from time to time and that keeps you alert.

    If you drink to much you will fall asleep and then fall over.

    As I said it's an art, practice - practice -pratice

    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
  • LarryCLarryC Member Posts: 331
    Version 1


    So how is this.  Come out of the skim port, 90 down into a large diameter pipe/sightglass.  Bottom of large pipe reduces into a vertical tee.  Come out of the bull of the tee to your oil drain.  Bottom of the tee goes into a low capacity pump.  Pump discharge into return.  Adjust pump flow to maintain a constant level in the big pipe that is slightly below the skimming waterline.

    Maintain a high water level hot boiler and drain oil as necessary.  Pump would probably be a variable speed to match water flow rate.
  • JStarJStar Member Posts: 2,668
    My idea

    No controls. Just piping. Periodically drain the oil trap.
    - Joe Starosielec
  • Danny ScullyDanny Scully Member Posts: 645
    edited September 2012
    Here's my idea

    Here's my idea, use all pre-cut nipples. I haven't cut/thread pipe for a steamer in years. Here's your material list, (2) 2 x 24 blk nipple, (2) 2 x 18 blk nipple, (2) 2 x 12 blk nipple, (2) 2 x 10 blk nipple, (2) 2 x 8 blk nipple, and 3-4 sets 2" blk nipples close through 6. No oil :)
  • Skimming circuit

    The oil "leg" of the skimming circuit has to be connected at the bottom into the returns, as the boiler steams, the oily water is thrown up into the top of the skimming circuit. The leg never overflows as the waterline remains the same as the boiler waterline; however the oily water remains in this leg, and can be drained out with a valve placed a little below the waterline. I thought of this while my wife was using a grease separater while making gravy.

    If the leg were closed at the bottom, the pipe with the oil floating at the top would overflow back into the boiler.

    If this would work, it would save people following BobC's instructions many trips to the bathroom! It would also save water otherwise trickling out during skimming.--NBC
  • LarryCLarryC Member Posts: 331
    Version 2

    Same but different.

    Hose from skim port empties into 5 gal bucket.  Create near bottom tap in the side of the bucket.  Plumb transfer pump between bucket outlet and boiler return.  Add float switch that only empties the bucket 2/3 of the way.

    Water dribbles in, when the water level hits the high set point, pump kicks in, recircs water back into boiler, turns off pump when bucket level reaches low set point.

    Use a low flow pump to keep things running at a low rate to minimize turbulence in the bucket.  Depending on quantity of oil, use a paper towel to remove excess oil film from surface of bucket water.
  • No pumps needed

    I let gravity do the work in my plan. The oily residue can be drained off from the skimming leg, every week or so in the first few months of operation, and once a season in subsequent years.if my boiler were new, I would make this work, but to put this on now would not give it the test it needs.--NBC
  • LarryCLarryC Member Posts: 331
    Version 3

    Translucent 5 gallon container with cover.  Add a dip tube that ends a few inches above the bottom of the container.  Same idea as Version 2.  Hose from skim port into the top of container.  Take a pump suction from the diptube.  Pump discharge back into boiler return.  Mount a low flow rate pump onto container.  Prime pump by filling container from boiler return line before opening skim port valve.

    Advantage is the oil is in an easy to carry container.  Wrap hoses and power cord around buck for easy storage and transport.  Clean out bucket and use for mixing and adding chemicals too.  Make the dip tube height adjustable according to use.
  • LarryCLarryC Member Posts: 331
    Where is the pressure?


    Where is the pressure forcing the de-oiled water back into the return?  The standing column outside the boiler and inside the boiler would be the same.  If anything, the outside column would have less static pressure as the quantity of oil in it increases.  It would also have a greater headloss as it has to push back thru the assorted fittings to get back into the boiler.

    Would a sightglass mounted between the skim port and the boiler return perform the same function as an oil catcher?
  • Gravity

    This skimming circuit is like a sight-glass or surge column. The water level in it is identical to that of the boiler. Any water added to the top port will not raise the level higher than the boiler waterline because of the connection at the bottom. Oily water splashing into the top connection will float in the column at the top, and because of its lighter weight will not pass down through the bottom connection into the return.

    When time comes to empty it out, close the valve at the bottom, and and open the discharge valve to drain the oily contents into a bucket.

    The principle is just capturing a small pertaintage of surface water constantly splashing into the column, during firing, and preventing the oily component from getting back into the boiler itself. As time goes on, more and more oil will be in the column, and less and less in the boiler. As more splashing occurs at the beginning, after the installation, more oil is removed then than 3 months letter. The Top connection to the boiler should be as large as possible so as to capture more splashing. If the column is not emptied, then you're right in saying the lower density will cause the waterline to be higher in the column than the boiler.--NBC
  • LarryCLarryC Member Posts: 331
    Please excuse my ignorance ...

    Please excuse my ignorance, but I thought the skim port was higher than the steaming waterline?  If that is the case, then how will any appreciable amount of oily water splash into the oil capture piping?

    I am under the impression that one overfills the boiler up to the skim port, fire it at a level to not produce steam. and remove water out of the skim port to capture and remove the oil film that is floating on the top of the water.

    Would it be possible to make an oil capture material shaped like a sauge that could be inserted and removed thru the skim port and just absorb the oil floating on the surface.  Something that absorbed oil but doesn't absorb water.
  • Splashing

    None of us can see into the boiler while it is steaming, but I would say that with the oil from a fresh install present, that there is a lot of splashing. Some of the oil will splash up against the top of the steam chest, and some will splash into the risers. All the oil splashes would return back down into the boiler, except for that oil which has splashed into the skimming leg. That oil will remain there until it has been drained out of the top of the pipe.

    The amount of oil trapped in the leg is not large at any one time; however even the constant removal of 1% per hour will result in all the oil ending up in the leg, and not in the boiler proper.
  • Charlie from wmassCharlie from wmass Member Posts: 3,925
    Take a pipe the length of the boiler minus 4 inches

    That is the size down from the boilers skim port. I will use 1 1/4" as the Weil McLain I just installed had a 1 1/2" port. Make the pipe stainless steel and cut it so it is missing a slot that is 1/3 of the top radius. weld this into a stainless steel nipple like a dip tube and mark the nipple so you know where the slot is located. Weld a little half moon on the inner end. then pipe this to a 2"x 1 1/2" elbow and a 2" x 10" nipple with a valve on it. As to boiler works away it will give you a trough to catch the oil splashed around and the large nipple will act as a catch.
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
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