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Help with optimizing near boiler piping

SteamworkS Member Posts: 14
Hi all.I'm in the planning process for replacing my oil burning steam boiler with a Weil McLain gas burning steam boiler.  Would some of you mind helping me optimize the near boiler piping so that it generates some dry steam with minimal waterhammer?

Current system:

Old boiler = American Standard thought to be from the 1970's (model unknown)

Parallel flow 1 pipe steam system

EDR 407.5 sq feet2

Mains in the basement = 2 inch pipes each

2 Wet returns running along the floor = 1-1/4 inch pipes each

Single 3 inch tapping feeding into a 3 inch header


New boiler: Weil McLain EG-50 gas burning steam boiler

According the installation manual:

Single riser 2-1/2 inches

Header 2-1/2 inches

Equalizer 1-1/2 inches



1) In order to reduce the steam velocity coming into the header, can one add on an extra tapping to this particular boiler?

2) If one can't add on an extra tapping, can you upsize the piping of the riser and header to slow the velocity there?  If so, what's the maxiumum size you'd recommend?  Any downsides to maximizing the piping size beside cost?  (I'm willing to pay for dry steam).

3) If we increase the size of the riser, is this done on the casting of the boiler (at the level of the tapping), or would you use the 2-1/2" tapping and then use a union that steps up to a wider pipe early in the riser close to the boiler?

4) The manual calls for a 1-1/2" equalizer.  Dan (in his LAOSH book) says 2 inch has become his minimum.  Based on my wet returns, I calculated a 3 sq inch combined transverse area which is matched by a 2" equalizer (3.36 sq in).  And so if I stepped it up like "The Lost Art" book suggests, I should put in a 2-1/2 inch equalizer.  Any harm in putting in an equalizer of this size?  If it's not necessary, what size would you recommend?

5) Finally, by upgrading the pipe size of the header, riser, and equalizer (and maybe the tapping if that's even possible), does this negate any warranty by the boiler manufacture since we haven't followed their instructions?

Thanks to all.


  • KC_Jones
    KC_Jones Member Posts: 5,082
    Similar projects

    I am in the planning stages and installing almost the same boiler as you (EG-40).  First those Weil Mclain boilers come standard with 2-3" taps on the top so you have plenty of room for upsizing the piping.  In addition the specs in the manual are the minimum so anything under that isn't good, but going beyond what they recommend should never be a problem. Just my 2 cents worth.  I am sure some others will chime in on this.
    2014 Weil Mclain EG-40
    EcoSteam ES-20 Advanced Boiler Control
    Boiler pictures updated 2/21/15
  • SWEI
    SWEI Member Posts: 7,356
    Can you post some pictures

    of the existing boiler and piping?  You might be able to re-use the existing header.  I would definitely use both outlets if it's at all practical.  If the tappings are 3", you should use at least some length of 3" nipples, but those can be reduced to 2" in order to facilitate connection to the (hopefully dropped) header.
  • SteamworkS
    SteamworkS Member Posts: 14
    on reusing the header

    Header has to be redone.  It's under 24 inches from the water line - though I know the boiler could be dropped since the current boiler is raised on a pedestal.  I get a TON of wet steam throughout almost all radiators in the house.  It also bullheads into the equalizer which I don't like.  I can post pictures when I get back but I'm pretty set on redoing the header.
  • SWEI
    SWEI Member Posts: 7,356
    A drop header

    does not have to be 24" from the water line, as long as the risers are piped up and over that level. 
  • SteamworkS
    SteamworkS Member Posts: 14

    Sorry this has taken so long.  Had a run in with some water in my basement after a heavy rain.

    Here're the pictures.  Didn't know that about the dropped header.  It's about 33 inches from the water line to the bottom of the mains.