Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

Getting Hissed

SPP Member Posts: 6
I recently had my Burnham oil boiler replaced for my steam system with a Weil Mclain boiler. Like the Burnham, the new boiler heats the hot water for the indirect hot water heater. I never had any problems with the water level with the Burnham and it heated the hot water just fine. It is a different story with the installation of the Weil Mclain. I will have the water filled to the correct level and then the water heater will kick on causing the water level to drop below the safe water level which in turn kicks on the safe water cutoff.  Naturally, I fill the boiler back up to a safe level but when everything comes back to a rest the water level is so high that I cannot see the top of the water on the glass gauge. What is causing the water fluctuations?  


  • Sil
    Sil Member Posts: 72
    I am no pro...

    But the real pros will want to see the pictures of the piping around the new boiler.

    New boilers use much less water than old boilers so the near boiler piping must be done to manufacturers specs. Chances are there is an issue with the near boiler piping.

    Another issue could be slow returns. Were the returns replaced along with the boiler?

    Have no fear... post some pics... and the experts on this board will walk thru the possible issues...
  • nicholas bonham-carter
    weil mclain piping

    did the installer leave you a copy of the installation manual for the new boiler? if not it is available on line. have a look at it and compare the piping diagram with what you have, and i think you will find that the differences will explain the cause of your problem--especially in regard to the copper pipe used for the steam supply. some more pictures will tell us for sure what needs to be changed, beyond all the copper pipe.--nbc 
  • icesailor
    icesailor Member Posts: 7,265
    Hissing Copper:


    A stupid question. What is the problem with copper tube on the supply of a steam boiler? Personally would always use steel screw pipe but I'm curious about the copper.

    Solder?  50/50 solder melts at 360 degrees. Silverbrite lead free is 450+. And it has less leaks. Like I said, I would have used screw pipe, no matter what. Why else would I own a Powerdrive?
  • BobC
    BobC Member Posts: 5,479
    Copper headers

    As i understand it the problem with copper is the difference in expansion rates compared to cast Iron. If you use both steam outlets on a boiler, the differing expansion rate can tear a boiler apart unless you have very long vertical uprights. Most boiler manufactures specify swing joints just for that reason. i certainly wouldn't allow a copper header on my boiler, nor would I want a welded steel header.

    If only a single outlet is used that wouldn't be a concern but the constant expansion/ contraction might cause a joint to fail over time.

    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
  • Jamie Hall
    Jamie Hall Member Posts: 23,446
    Piping and copper

    as nbc notes, the near boiler piping on that Weil McClain is just not good.  In terms of the arrangement, never mind the material.  That, plus slow returns, may be the water level problem.  If you have an automatic water feeder, try setting it for a much longer delay on feed, to allow the water to return to the boiler.  If it's a manual feed (sounds like it?) wait, if you can, for the water to return before you bring it up to level.  Also, you can run a Weil McClain fairly high cold -- say 3/4 of the way up the sight gauge -- without problems IF your near boiler piping is right -- don't try it with what you have; you'll get a lot of carry over.

    On copper -- the problem is the thermal expansion difference.  It is possible to arrange copper in such a way as to minimise the problems, but if the header is copper and there are no swing joints with long (12 to 24 pipe diameters between elbows) legs, and two or more outlets from the boiler, the header is going to pry the boiler apart.  Even with the long swing joints, and elsewhere in the steam piping, copper should be arranged so that joints are stressed in bending, not torsion, if possible.  On the whole... threaded black iron works a lot better!
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • SPP
    SPP Member Posts: 6
    bogus piping ?

    There is a manual fill on the system and so far since the boiler was installed I have used it almost exclusively to heat my hot water as I use my pellet stove as my primary heat source. So the returns haven't really come into play. All of the water fluctuation happens when the water heater kicks on. The water is at a good level when the water heater kicks the boiler on but then is too full when back at rest. So the piping is my big problem here? Again, I really haven't used my boiler to make steam.
  • crash2009
    crash2009 Member Posts: 1,484
    It looks like a SGO to me

    Here is the manual for the SGO line.   http://www.weil-mclain.com/en/multimedia-library/pdf/weil-mclain-pdf/products/boilers/oil-boilers/sgo/sgo-boiler-manual.pdf.pdf 

    If you go to page 17, and look at the picture, specificly the minimum to bottom of header distance should be 24".  It appears that your distance is only about 12". When your indirect calls for hot water, the boiler fires to start making steam.  The water in the boiler is boiled out causing the low water condition.  Its running like a coffee purcolator.  Pumping or purcolating the water up into the mains, and returning by gravity to the 2 wet returns that you have.  From the 2 wet returns which are joined together, the returning water is forced through an even smaller pipe back into the boiler to be re-heated.  While the water is on a tour of the perimiter of your home, You and the automatic water feeder fill the boiler up.  I hope this has answered your question. Oh yea, one more thing, The waters job is to stay in the boiler.
This discussion has been closed.