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Water Hammer

Just a home owner that just read all the books. I have serious water Hammer and water in my air valves. I just finished making sure the radiators are slightly angled for back flow.

Some radiators are clod at time when they should have been hot. I need some vari Valves before the winter. Anyone has a good company to recommed. Single pipe stream system.


  • eComfortUSA
    eComfortUSA Member Posts: 11
    Water Hummer


    As i know two form very good companies on steam valves is Dole and Gorton. They are not inexpensive but it pays in long term. Before you will buy valves, i have question, did you did any work on the boiler or near boiler piping since last winter? If no, go on-line, just be careful, most of the on-line stores call Vari-Vent Adjustable any radiator steam vent. Or call us at 866 554 4328 or send e-mail with request at [email protected], we don't post these items but we have them in stock, plus you will have chance to talk to technical support, maybe you can avoid purchase.

  • 1-pipe steam water hammer

    check your main vents for operation, and you may need to increase their number, and capacity. in my experience, the radiator vents do not plug up as quickly as the [maybe improperly installed] main vents. start with those first, and just test trhe radiator vents with the "blow-through" method. also the radiator vents only have capacity to handle the air removal of the riser and radiator, leaving the main vents to handle the large volume of air in the boiler, and main steam lines. don't be paying for extra fuel to squeeezze your air out-let it leave easily on it's own through generous MAIN-LINE VENTS!!! 

    did you have water-hammer last season? if it has suddenly appeared, then check your steam pressure with a good low pressure gauge [gaugestore.com-0-15 ounces ] on the same pigtail as your vaporstat. make sure the system is in the 3-12 ounce range for quickest response. your pigtail may have become clogged, and unable to let the vaporstat "feel" the boiler pressure.

    if the waterlogged radiator condition persists even with proper low pressure and venting, then look at your boiler water-line: is it steady, and clean? check your near boiler piping and compare it to the downloaded mfgs's installation in structions.--nbc
  • MosesHomes
    MosesHomes Member Posts: 7

    Thanks, I will check the main vent. The boiler was newly installed in 2005 and did not have the problem. It started last year. I will test the radiator vents and main vents and keep you posted.
  • Jim Pompetti
    Jim Pompetti Member Posts: 552
    Newer boiler

    Is the boiler (inside) clean. Take a look at the glass and ,see if it has and oil or dirt floating on top.
  • Jamie Hall
    Jamie Hall Member Posts: 22,972
    There really aren't too many ways...

    that a one-pipe steam system can hammer -- and they all boil (sorry) down to one thing: somewhere you have a pipe or pipes which have water in them that can't drain out freely.  If this didn't start to happen right after the new boiler was put in, then it's probably not the near boiler piping (although if it is marginal, boiler problems which might not otherwise be noticed can be aggravated).  Nick has a good point: make darn sure your pressures are low enough; that can make a big difference.  Also as someone noted, make sure that the boiler water is at the right place in the glass -- it should be marked on the boiler, but if not, generally a third of the way up the glass is about right -- and that it doesn't "bounce" around too much when the boiler is steaming.  Having gotten all that checked out, see if you can figure out which radiator is banging -- this can be difficult, as the sound telegraphs through all the pipes, of course.  If you can, start there and make sure that the pipe slopes are generous, and that the water has some place to drain back to and can get there.  This may take some pipe tracing, but it's really kind of fun.  If you can't, or just on general principles, do the same thing for all the pipes and radiators.  Think like water: you have to be able to get back, all down hill, to the boiler somehow!

    The vents are another matter.  As Nick notes, you really do need main vents at the ends of the main(s) in a one pipe system.  Technically you might not, but they will make the whole thing much more even, much quicker to heat -- and cheaper to run.  They are not adjustable!  The radiator vents can certainly be variable.  Once you have the main venting, though, a cold radiator is only one of two things: the vent is stuck shut (it happens) or the valve is closed!

    And speaking of valves.  Valves -- all the valves, but especially radiator valves -- in a one pipe system must be either open all the way or really tight and closed.  Preferably open.  Control your room heat with the vent, not the valve.  A valve part way open is a guaranteed water hammer.  Maybe I should have mentioned that first...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
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