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skimming new boiler

I just learned how to skim my boiler while observing a tech do it the other day.

however, he did not turn the boiler on while skimming b/c the took out the electrical connections to the controls.

is it absolutely a necessity to cycle on the system while skimming or can one get by without turning it on?


  • jayh
    jayh Member Posts: 1
    skimming new boiler

    Can someone walk me thru this process since I've not done it before.
  • walking and skimming

    a copy of dan's book, "the lost art of steam heating" would be very useful to you as it has several pages devoted to this [available here].

    simply put, make sure you have a tapping above the normal waterline with a valve on it. if you can also temporarily pipe it to over to a floor drain, that would help, as you are going to add water slowly so as to elevate the waterline to the tapping height, and let water flow slowly off the surface [where the oils, etc. are] out the valve. all this being done while switching on the burner periodically to keep the water hot, but not boiling.probably takes a couple of hours, maybe more than once.

    now my favorite rant-why has no one come up with some arrangement to do this automatically? it's so necessary to do this but, does take time. why not make it automatic??????????????????????????????????????????--nbc

  • Dan recommends "cold skimming"


    Look down the page in the section above "One-pipe Steam"

    Generally you have to skim several times or more. I did it on 5 consecutive Saturday mornings.
  • David Nadle
    David Nadle Member Posts: 624

    In my experience you can skim cold. The trick is to do it very slowly--just a trickle on the feed water--and do it for a long time each time. Hours. Once you get it going you can leave it unattended for chunks of time. I was filling a 5 gallon bucket in about 2 hours. You can do it while you watch football.
  • Dan Haraburda_2
    Dan Haraburda_2 Member Posts: 13

    Thanks. I need some further clarification if you will in laymen terms:

    I read the newsletter and what is meant by cold skimming? Both occasions, I skimmed after the unit has been cycled off for bout say 2 hrs. The water that comes out is still hot. Is this cold skimming? or is cold skimming pertains to shutting the unit off for a few days then skim?

    what is meant by horizontal skimming? the tech applied a nipple on the pressure trol feed. is this horizontal skimming?

    Thanks ALL.
  • David Nadle
    David Nadle Member Posts: 624

    I don't know what horizontal skimming is. The actual temperature of the water is less important I think, than that there hasn't been recent turbulence to mix the oil and water, so most of the oil is on the surface of the water. 2 hours might be a bit short but not too bad I guess.

    If your tech removed the pigtail and skimmed through that tapping, it's probably because that was the easiest or safest one to open. I would make a skimming kit out of a 1/4" nipple, a hose adapter, and a length of hose, so you can cold skim right into a pail.
  • Dan Haraburda_2
    Dan Haraburda_2 Member Posts: 13

    so the term cold skimming is just arbitrary?
    i should not worry about the temperature of water coming out of the skim port?
    in that case, i think i havent skimmed long enough...
    both instances, the tech skimmed it for about 25-30 mins max.
  • David Nadle
    David Nadle Member Posts: 624

    No, it's not arbitrary. It means the water isn't being heated during the skim. There's no way a tech can afford to spend all afternoon in your basement watching water trickle into a pail. But you can. Advantage, you.

  • David is giving you good advice.

    Oil being lighter than water floats to the water's surface. As the oil is a very small amount what you are trying to do is skim off the very surface of boiler water (just the oil and a very small amount of water) This skimming has to be done v-e-r-y slowly so not to cause any turbulence which would mix the oil with the water. Slower = Better

    David's mention of filling a 5 gal bucket in 2 hours gives you an idea of how slowly skimming should be.

    A poor tech doing the skimming is caught between a rock and a hard spot. He has other jobs to do and also knows if he stays and properly skims the boiler that the homeowner will go through the roof when he gets the bill at the hourly rate for "you just stood around doing nothing".

    I mentioned in a previous post I did my skimming on consecutive Saturday mornings. Skim for a few hours, run for a week and then skim again. I tend to think that colder is better as the oil has less viscosity and that means it won't mix as readily with the water, however, I don't see this as being absolutely necessary and especially this time of year may not be very practical.

  • I like

    hot skimming myself .

    We add a mild cleaner to the system and let it steam till the returns are clean ( you need a purge valve setup on the return to do this ) . While hot we skim slow , a gallon a minute or so . We keep skimming till all the cleaner is out of the boiler . A typical residential sized steamer takes around 30 gallons of skimming till the cleaner is gone . Been using this method for years on our new installs and works great on all but the dirtiest of steam systems .

    The returns on this system were so filthy , we had to return a few days later to clean and skim again .
  • tim smith
    tim smith Member Posts: 2,600
    Ron, do you ever just waste the condensate to the drain on

    a dirty return system and feed fresh water until returns start running clear?? I am doing this on an old 1908 church right now to get it to clear up. Then I will skim boiler again. Just wunderin.
  • Dan Haraburda_2
    Dan Haraburda_2 Member Posts: 13

    sorry, my last question.
    I have a Burnham boiler with no dedicated port for skimming. Can i basically use remove any controls(i.e. pressuretrol or pressure relief valve) that are above the waterline and add a nipple to skim? or does it have to be the the pressuretrol port?

    Thanks again!!
  • Yep

    We keep the boiler steaming while the returns are flushed . And dump all the crappy condensate . Once you have steam coming out of the hose on the return , the pipes are usually cleaned as much as possible .

    But this install was worse than normal . Steam and chocolate milk were coming out at the end . At that point we decided to backflush the return - we ran hot water from the coil directly into the return pipes and drained them . Repeatedly . It helped , but we still had to go back .

  • Frank- what model Burnham do you have?
  • Dan Haraburda_2
    Dan Haraburda_2 Member Posts: 13

    IN5, Steam for one pipe and gas fired.
  • Burnham gas steamer

    We add a tee where the relief valve port is or where we pipe the pressuretrol and gauge . I'd like to see a larger port for skimming on these boilers though .
  • Dan Haraburda_2
    Dan Haraburda_2 Member Posts: 13

    u added a tee and a plug. so when you skim, you just remove plug from the pressuretrol tapping as i can understand it. right?

    addtionally, is there advantage to stack the preesuretrol above the pressure gauge? mine was hooked up in two different places and the manual has the same set up.

  • Ted Robinson
    Ted Robinson Member Posts: 126

    There is a 1 inch tapping on the right side that seems ideal for skimming.

  • Frank-

    Look at the picture Ron posted. See the tee and yellow handed valve under the pressuretrol.
  • Kara
    Kara Member Posts: 36

    right i see the tee and the hand valve.
    my set up is a lil different. Please elaborate on your point.

    if he uses that hand valve for skimming(i see plug on bottom), i assume he needs to also open the manual feed as well to get water in the boiler?

  • Frank-
    As Ted mentioned there is a 1 inch port available for skimming on your boiler. See the Burnham IO manual Page 6


    Take a look at the port marked "L" ("Factory Plugged
    Surface Blow-Off"). This is the "designated" skim port or you could do it as Ron mentioned.

    Are you have problems with wet steam? While you can plumb that unit using one exit port from the boiler, using the two ports that are available should make for dryer steam.

    See Page 17 in your IO manual. The "Alternate Piping Method" on the right side of the page. It's plumbed with swing joints and is the ideal drop header setup.

    However if your system is working fine, leave it alone. As was said in another post "If it ain't broke, Don't fix it! "

  • Frank-
    Yes, the object of the whole skimming operation is to OVERFLOW the water v-e-r-y s-l-o-w-l-y out the skimming port.
    To make it over flow, you must add new water very slowly, using the manual feed.
  • Kara
    Kara Member Posts: 36

    Rod, thank you so much for your help.

    I am having surging problems with the site glass and i would assume this will be wet steam.

    My unit was never skimmed since installation last year.
    I heard from this forum that skimming solves many issues, so i figure i start here.

    let me make sure i got this down pact before attempting tonight.

    i have to add a temporary pipe onto the tapping "L". then open the manual feed slighlty so the water overfills to the top of sight glass. Water will begin to drop down on my bucket?
    after about a few gallons, i will shut the manual water feed, remove pipe and plug tapping.

    Then i would go do to blow down (thru drain below water level) the boiler to get water level back to normal?

    is this the correct process.

    I promise, this will be the last question.

    the tech that came over that skimmed removed my pressure limit and added temporary piping there. i just wanted to make sure he did it right. i wont be calling them back as i now know how to do it.
  • David Nadle
    David Nadle Member Posts: 624
    Sounds good.

    but you may want to add a permanent nipple with a cap to the skim tapping, because you may have to do it a few times, and then all you need to do is remove the cap.

    Also, "blowing down" is done under pressure; all you need to do is drain the water to the correct level.

    Most important, keep repeating the skimming until the surging is gone.

  • Frank-
    You can leave the skim port piping in place. In fact it is better to do so as the pipe plug in the boiler port tends to become "permanent" (rusted in) over time and then has to be drilled out to be removed. At the minimum you should leave a nipple and a cap attached to the port.

    Ron's setup (in his attached picture) with a nipple, elbow, a ball valve, then another nipple, coupling and
    a plug makes a lot of sense. I have the same on my own boiler's skim port, without the plug in the coupling as I don't have kids (they're adults now) so don't have to worry about one of them playing with the valve and accidentally getting scalded. I'd just leave this in place and then you can skim when ever you want to without a lot of effort in attaching more fittings.

    Initially you'll probably have to do at least 2 or 3 skimmings to get all the oil film out. Skim, run it a few days, skim again, and so on. Remember you want the boiler cool before you start skimming. You seem to have the process down right.

    Ask as many questions as you want. That's the way we all learn.
  • Kara
    Kara Member Posts: 36

    Rod/Ron/David and co.
    you guys are amazing!

    Thank you so much. will return with my experience.

    Happy New Year gents.
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