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Master Vent Sizing

I'm looking to even things out a bit (and spend less money on oil) in my one-pipe system by adding top-of-riser main venting. This is an idea I've been kicking around for a few years but thought it was kooky 'til I read Lost Art and some postings around here.

Right now, I have no working main venting. Can anyone suggest main vent sizes?

I have two mains. The rear one is dry return, angled up and away from the boiler for about 5 feet, and then into a 30-foot riser supplying half of my radiators. The main and riser are both 1+1/2" pipe.

The other main is a wet return, 2". It's 40 feet long and runs to the front of the building. Halfway through, it feeds one 2" intermediate riser which is 15 feet high. That riser then splits into two 2" risers which continue for another 25 feet. There's no radiation on these middle risers other than the pipes themselves, just a Hoffman 45 at the top of each.

At the end of the long main, there's a 35-foot 1+1/2" riser feeding the other half of my radiators. The only main vent in the system is at the end of the long main, before it drops into the wet return. The main vent doesn't work.

It takes 15 minutes from cold start (170o aquastat) to get steam to the tops of the front and rear risers. It takes 30 minutes(!) from cold start to get steam to the tops of the middle risers (with no radiators.) How much can I expect these numbers to drop with top-of-riser venting?

Thanks,
Mark

Comments

  • Thad English
    Thad English Member Posts: 152


    > I'm looking to even things out a bit (and spend

    > less money on oil) in my one-pipe system by

    > adding top-of-riser main venting. This is an

    > idea I've been kicking around for a few years but

    > thought it was kooky 'til I read Lost Art and

    > some postings around here.

    >

    > Right now, I have

    > no working main venting. Can anyone suggest main

    > vent sizes?

    >

    > I have two mains. The rear one is

    > dry return, angled up and away from the boiler

    > for about 5 feet, and then into a 30-foot riser

    > supplying half of my radiators. The main and

    > riser are both 1+1/2" pipe.

    >

    > The other main is

    > a wet return, 2". It's 40 feet long and runs to

    > the front of the building. Halfway through, it

    > feeds one 2" intermediate riser which is 15 feet

    > high. That riser then splits into two 2" risers

    > which continue for another 25 feet. There's no

    > radiation on these middle risers other than the

    > pipes themselves, just a Hoffman 45 at the top of

    > each.

    >

    > At the end of the long main, there's a

    > 35-foot 1+1/2" riser feeding the other half of my

    > radiators. The only main vent in the system is

    > at the end of the long main, before it drops into

    > the wet return. The main vent doesn't

    > work.

    >

    > It takes 15 minutes from cold start

    > (170o aquastat) to get steam to the tops of the

    > front and rear risers. It takes 30 minutes(!)

    > from cold start to get steam to the tops of the

    > middle risers (with no radiators.) How much can

    > I expect these numbers to drop with top-of-riser

    > venting?

    >

    > Thanks, Mark



    Mark,
  • Thad English
    Thad English Member Posts: 152
    venting

    Mark,
    I am not a pro, just a homeowner with an interest in steam, but I do know that you should replace that main vent that is not working before you do anything else. Getting all that air out of the 2" main will only speed things up. I would imagine that a Gorton #2 would be a good main vent to use here.

    Next, make sure your pressurtrol is set to under 1 lb. Then, insulate all those mains, and finally, make sure that the vents on your radiators are working. The key to getting the steam to your rads fast is making sure that the air has a place to go easily and quickly.

    Good luck,

    Thad
  • Steamhead
    Steamhead Member Posts: 16,736
    The charts you need

    are in the workbook that comes with the "Dead Men's Steam School" video. This would be a good purchase for you, since Dan goes thru the procedure for sizing vents in the video. And you'll really enjoy seeing him doing his thing- I always do!

    Order yours on the Books and More page of this site.

    To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
  • superMARKet
    superMARKet Member Posts: 87


    I'd get a kick out of seeing Dan in action in person, too - looks like I'd love the Lost Art seminar. D'ya get much of my type at those events? (That would be the hands-on building manager-ish superintendint-ish type.)
  • Steamhead
    Steamhead Member Posts: 16,736
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
This discussion has been closed.