Main Steam Vents

Larry_10

I'm changing the main vents. The current ones have been threaded into 1/4" holes. I'm putting in vents with 3/4" threads.

The front main vent is 6" from end of main and isn't raised on a nipple. I'll drill a new hole 15" from end of main and raise it on an 8" nipple.

The rear main vent is 4" from end of main. The rear main vent is sandwiched right between a return line and a steam riser. In order to move the main rear vent 15" from the end of the main, I'd have to place it before the riser.

Did the Dead Men intend for the rear main vent to be placed between the return and the riser or was that a later modification?

Also, what's best way to remove drill filings from inside of main once hole is drilled and tapped? Should I drill a hole on underside of main, then plug it?

Many, many thanks for your input.

Robert

Steamhead

You can get away with

some of these less-than-optimum vent locations. What you want to avoid is water slamming the vents. Considering most new boilers have lower waterlines than older ones, this shouldn't be a problem. Putting the vents up on nipples will help also.

I'm guessing whoever installed those vents put them there since the original installer didn't use vents at all. If the present vents are in holes drilled and tapped into the pipe, they were added later.

Have you checked the length and diameter of your mains to size the new vents?

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Larry_10

More on Quick Main Vents

Dear Mr. Wilsey:

Dan Holohan said of you, "they don't get any better than him." Thank you for your speedy reply.

I want to move the rear main vent farther away from the end of the main. It's just four inches away right now.

In order to do this, I will have to take the existing rear vent out of it's sandwiched position on the main which is between a return and a riser. If I do this, the new rear vent will be about 30" from the end of the main.

The boiler is not new, but even to Keyspan's frustration (they want to sell us a new one), it still hums beautifully.

There are 3" mains piped to the boiler. The front main is a bit more than 25' long and the rear main is just over 35'. I spoke to the people at Gorton and they said I could install the big ones, #2's - - one at each end. I have the #2's and nipples that will raise them 8" high on the main. Can I proceed?

Any advice on how to get the drill filings out of the main after I drill and tap? I have some off Dan Holohan's books on steam, but nothing on this.

Larry_10

Main Vent Follow Up

Dear Mr. Mandel:

My apologies, I thought you were Mr. Wilsey. Still, many, many thanks for your speedy reply.

Steamhead

Actually you were right the first time

"Steamhead" is actually Frank. I'm the computer-literate one, but Rick is learning.

The Gorton #2 vents will work fine as you have planned the installation. The best way to keep drill shavings out of the main is to keep them from getting in. Brush them off the pipe as you drill. The few that do enter the pipe shouldn't hurt anything.

Let us know how well it works!

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Dave Stroman

Hey Steamhead, The local suppliers in the Denver area seem to stock only the Hoffman #75 or #76 for main steam vents. That is what I have been using. They say they are for medium and large steam systems. I see you talk about the Gorton vents a lot. What is so special about them?

Dave in Denver

Hitzkup

question for steamhead

i'm the one who asked you a few days ago about adding an elbow and a 15" nipple before the main vent. don't you think that this will work for roosterboy?

mark s

Steamhead

Capacity

The reason those guys tell you that is so you'll buy what they have. But consider this: The Gorton #2 has about four times the capacity of those Hoffmans, but costs roughly the same. The Gorton #1 has about the same capacity as the Hoffmans, but costs less.

Hoffman's vents are generally of good quality. But they were sized during the Coal Era when steam came up a lot more slowly than it does now with oil or gas.

The vent sizing technique we use here comes from Frank Gerety, a very innovative engineer from New York. Mr. Gerety did a lot of original research (and wrote a very good book too, "How to get the Best from One-Pipe Steam" which I believe is out of print) with the goal of getting the best possible results from existing steam systems. Basically he calculated the amount of air in the pipe he was venting, then selected his vents so the steam would fill the main in about a minute. This is much more accurate than those "medium and large" systems they cited at the supply house.

That's the goal here- fill the mains with steam quickly, so it will be available at each radiator runout before starting to enter any runout. BTW, to see the Gerety "Master Venting" charts and some examples of their use, get Dan's "Dead Men's Steam School" video and workbook.

Mr. Gerety based his vent sizings on the Gorton #1 vent, used in multiples as needed. Since four #1 vents equal a #2, I use the #2 where it is called for. I sometimes take the basic vent sizing and double it on very long wrap-around-the-basement mains where the entire boiler output goes into just the one main.

Hoffman's biggest vents are the #75 and #76. This is one reason I don't use them much except on shorter mains. The Hoffman #4A is much smaller than this but still works well on very, very short mains. Gorton makes the biggest vent on the market today, the #2, and I've had lots of success with it. That's why I recommend its use. Now, if Hoffman restarted production of their old #10 vent, they'd give Gorton a run for their money. But I seriously doubt that will happen.

If you can't find Gortons in your area, get in touch with Ken Kunz at Gorton and tell him I sent you. He will see that you get what you need. Gorton's site is www.gorton-valves.com .

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Larry_10

More On Main Steam Vents

Hello, Mr. Wilsey and Mr. Mandel:

Thanks for the green light on the #2's. I drilled and tapped a 3/4" hole. Brushed the shavings away, like you advised and used a magnetic screwdriver to pick up any strays on the inside of the main.

So, the #2's are in and standing proud on their 8" nipples. The system is still humming.

Do I need to remove the old main vents that are close to the end of the mains? They are Gorton #1's, but they were reduced to 1/4" threaded openings ( a no, no.) via a coupler.

They don't seem to be doing any harm. Do you think I should remove them and plug the holes or just leave them?

Again, many, many thanks for the help.

Robert

Steamhead

I'd remove them

since they were not installed correctly. The reduced piping my cause condensate to build up underneath them at some point, which could result in a leak. Remove them, plug the openings and use them elsewhere (with proper piping) if they're still working.

Glad to hear the #2 vents worked so well.

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Larry_10

Apologies to Roosterboy

I have been posting about main vents, anticipators, thermostats, and pressuretrols - - under Roosterboy.

I thought that was a name that was automatically generated for me to use. It kept reinserting itself in the sender info boxes. Anyway it has been corrected and my apologies for any inconvenience.

Many, many thanks to you, Steamhead, I'll remove them.