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Mo-WHAT ?

Steamhead
Steamhead Member Posts: 16,732
There HAS to be a vent somewhere on that dry return. In the Mouat, like most Vapor systems, the air from the radiators passes into the dry return and leaves thru a central air vent. Sometimes the vent is part of a Float Trap/Air Eliminator, Return Trap or Regulator. Less-well-educated people sometimes remove these when replacing a boiler and the insufficient-heat calls begin when they leave.

Check again. Go over every inch of the dry return. Follow every pipe connecting to the dry return- I sometimes find vents several feet from the return. If there's no vent, install a pair of Gorton #2 vents near the point where the returns drop to the Hartford Loop. If you can't find Gortons in your area, go to

www.gorton-valves.com

to find out how to get them. The #2 is a high-capacity vent that works great on Vapor, and it costs about the same as a Hoffman #75 which only has about 1/4 of the #2's capacity.

The steam mains should also be vented. Measure the length and diameter of each one, and we'll tell you what vents you need.

The new boiler should have a Vaporstat instead of a Pressuretrol. There are several Vaporstats available- you want the one that only goes up to 1 PSI. The Mouat system ran at 3-6 ounces, and the Vaporstat can control the pressure within those limits.

Your proposed pipe sizes sound good.

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Comments

  • Jim Walls_2
    Jim Walls_2 Member Posts: 71
    Mo-WHAT ?????

    Dan, Steamhead, Noel, Maddog, hellllllllllppppppppppppp
    Looking for some opionions & advice
    background,,,,,,,,,My parents celebrated 50 years of wedded bliss this past Saturday 10-18-03, as a small part of the celebration my wife & I & my younger brother & his wife attended a dance with them ( they have belonged to a dance club for 30 years. It was held at the local Elks lodge. While there, my mother happened to mention it was cool in the building because the boiler was being replaced & not complete yet. This was more than any red-blooded not dead yet wet head could take, you see, several years ago, I had toured some local buildings taking pictures of old steam systems, & I knew this building was heated by a Mouat Vapor system. I stealthfully exited & was in the basement before
    my wife could utter "don't you da........re".
    The replacement is being done by a local plbg & htg contractor who is a member of the lodge, he has however ( found this out yesterday) asked us to perform the welding on the project as he is not certified.
    I'am seeking knowledge from the mountain on the following items
    1. They chose a Weil-McLain LGB-10S boiler, installation instructions say only 1 riser necessary,,,,,,minimum size 5"
    there are 2- 6" tappings,,,,,,,,,,,would you use both or follow recommendation? which would match former piping


    2. header size 5",,,,,,,existing header is 4" with 2-4" takeoffs,,,,,,,,,,,,,header size recommended minimum 5"
    3. existing equalizer 2",,,,,,,,,recommended minimum 21/2"
    4. change pressuretrol to Vaporstat ???????
    5. I know nothing about the history of this system, other than a newspaper article that revealed the fact that it was a Mouat system installed in 1921, cannot locate the air relief valve, do know this is the third boiler original was replaced about 20 years ago, also has a boiler feed pump
    added to the system,,,,,,,,,,and oh yea,,,,,,,,last maintenance man added a radiator stop leak product to the now deceased boiler,,,,,,,,,,,
  • Steamhead
    Steamhead Member Posts: 16,732
    It is VERY IMPORTANT

    that the installer follow the boiler maker's pipe sizings. That said, it doesn't hurt to make them a bit bigger since this will slow the steam down and avoid the carrying over of water into the header.

    If you're going to weld the pipe, I'd stick with a single riser from the boiler to the header. A welded header will not allow the boiler sections to expand and contract as a header built of threaded pipe. If you use two risers into a welded header, the resulting unyielding yoke will probably crack the boiler. But I'd use the full 6-inch tapping and make the header 6-inch too, again to slow down the steam flowing thru it and separate any water that may get that far. And you'll definitely need a new equalizer- 2-inch is too small, and 3-inch is better than 2-1/2.

    The riser to the header also must be a certain height above the water line- most boilers call for 24-inches as a minimum. If you don't have enough height, you can use a drop header which allows more riser height and then drops into the main header. Here's one on a Columbia with two risers to the header- see how it works?

    Now about that main air vent- some versions of the Mouat system vented the dry return into the chimney. This allowed the flue draft to help pull air from the system. If the dry return doesn't go into the chimney, there's probably a strange-looking device that has three vertical rods on it. That's your vent.

    How about posting some pictures?

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    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
  • Mark Hunt
    Mark Hunt Member Posts: 4,909
    WOW!

    BEAUTIFUL!!!!

    Now tell us the truth Steamhead! What do you REALLY do for a living?

  • Steamhead
    Steamhead Member Posts: 16,732
    Thanks, Jon

    from Tom (a.k.a."Pop"), Rob and myself- the crew who installed that Columbia.

    To Learn More About This Contractor, Click Here to Visit Their Ad in "Find A Contractor"
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
  • Jim Walls_2
    Jim Walls_2 Member Posts: 71
    Thanks steamhead

    yes, plenty of height available, no problem with the 24", I did look earlier & cannot find a dry return to the chimney or the vent,,,,,,,,should I add a main vent? would it be best to use a thermostatic trap as the main vent, since the original vent had a water seal ? thanks for the heads up on the single welded riser vs. the 2 and chances cracking the boiler, you learn something new everyday, makes life worth living. We are only welding what he is installing, & I know the lodge is under financial strain, however we will only do the welding if they agree to do it correctly. I'am going to recommend he use 1 - 6" riser, remove & replace the 4" header with 6" and change the equalizer from 2"-3",,,,,,,,,,,what do you think about the vaporstat?
    Thanks for your help
  • Yes on the vaporstat

    Use a Honeywell L 408A 1132.

    0-1 PSI, by ounces. You'll love it.

    Noel
  • Jim Walls_2
    Jim Walls_2 Member Posts: 71
    Thanks Noel

    I appreciate the help, I very seldom get to work on these systems during the course of my dailey employment, told the trustee I spoke with, "this is more of a hobby than a job, thanks for letting me play" I used to be scared to death of steam, would not go near it, than I discovered Dan, & now I love it ! It is such a joy & comforting feeling knowing you guys are out there to bounce questions off of,,,,,,,,,Thanks again
  • Earthfire
    Earthfire Member Posts: 543
    Turn on

    Turn the Plumber that's doing the install on to the WALL, if he hasn't been here before. I still run in to guys once in a while who say they don't have the time for the internet till you lead them by the one typing finger( my style, by the way). Although none of us has ALL the answers, or will ever do things the same, the collection of ideas and inspiration here, (and the stuff that didn't work)helps me every day be a little better, I hope, at what I do for a living.( And has saved me from some costly screw ups)
  • KellyM
    KellyM Member Posts: 13
    Main Vents

    Where would you place the vents on the steam main in a vapor system like this? I am working on a similar system with some of the same issues and I am struggling as to where I should place them.
  • Steamhead
    Steamhead Member Posts: 16,732
    On the steam mains

    they should be after the last radiator takeoff but before the drip. The dry returns are usually vented near the boiler.

    To Learn More About This Contractor, Click Here to Visit Their Ad in "Find A Contractor"
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
This discussion has been closed.