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Replacing boiler that has Webster Vent trap

willie13 Member Posts: 7
I'm quoting a new boiler to replace the Ideal boiler, circa 1920, that currently works with a Webster Modulation Vent Trap. It is a 2-pipe system, in great shape, but since the boiler is leaking, we need to replace it. We have sized the radiation and I'm convinced I need a boiler feed tank since the new W/M BL-480 will hold far less water than the Ideal boiler. My question is do I need to keep the Webster Vent Trap, or since the air will be vented out of the feed tank vent, can I remove the Vent Trap without problems. I also plan to use a Vaporstat to keep the boiler operating pressure down to 8", which I read in Lost Art is the typical design pressure for these old systems. Thank you.


  • Jamie Hall
    Jamie Hall Member Posts: 23,313
    If you find you need extra water storage -- which you probably don't, but if you do -- remember that where you need it is at the water line of the boiler. There are several ways to do this, but by far the easiest all the way 'round is simply a nice tank -- as big as you like it to be -- not vented, but equalized. The tank is set at an elevation so that it will be about half full when the boiler is at it's normal water level, and connected to the wet return. It has an equalizer line to the steam main or header somewhere handy.

    Now you can also get fancy -- and unduly complicated -- and set a condensate receiver somewhere and have that vented, with a nice boiler feed pump or if you really want to get complicated and frustrated a condensate return pump. But besides adding complexity and maintenance, this runs a real risk of lowering the water level in the wet returns, which may dry out some drips preventing steam from getting into the dry returns, which will give you endless headaches and an unhappy client.

    Which reminds me: set that new boiler so that its water line is at the same elevation as the water line of the old one. Put it up on blocks if you need to.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • dopey27177
    dopey27177 Member Posts: 887
    do not remove the Webster system if it is functional.

    I don't like putting a boiler on blocks. A concrete pad is a lot more stable than blocks.

    If the concrete pad is to expensive install a false water line.

    If you install a boiler feed pump tie the vent into the dry return near the Webster modulating vent.