Main Vent size (aka Topic #1)

Jamie Hall

I have just installed a Weil-Mclain 580, firing at 4.45 gph, on a vapour heating system which has been much expanded. Works fine except: the main vent is a Hoffmann 75. Not surprisingly, the thing short cycles on pressure, and my surmise is that the Hoffmann 75 is nowhere near big enough. Running 12 oz. with an 8 oz. subtractive differential.

Anyone have experience on this? (Particularly Weil-McLain techies?) How big a Gorton might work? Or Gortons? And (I know this is dumb, but... I've mislaid it) Gorton's web site for ordering?

Comments?

Jamie Hall

[Deleted User]

i use gorton #2 main vents

they are about equal to 3 1/2 hoffman 75's if i remember right. I get mine from statesupply.com (out of minnisota) cause no one around here (cleveland) stocks them. I dont think gorton sells direct. If they do i would like to know that myself.

Ernie

Gorton

Sells direct. Nice people to deal with. Phone 908.276.1323
Fax 908.272.5881

Boilerpro_3

Vents may not be needed....

There are quite a few vapor systems that do not need any main vents.... just proper control of pressure and an open pipe. The ones I've seen have some type of condensor radiator or pipe in the basement where the main vent connects to the system that prevents the steam from reaching the open pipe (which may have connected to the chimney). If you do need them, sizing them is something I have net seen yet, other than sizing for venting mains. Oh where, oh where is our Steamhead Now!

Boilerpro

[Deleted User]

Hi Jamie

On your cottage, I don't believe I'd use less than a #2. It'll look real fine up on your Hoffman Differential Loop.

What happened with your old header?

Noel

Steamhead

Talk To

Ken Kunz at Gorton- tell him we sent you!

If the system is that big, a single Gorton #2 may not be enough. If you can hear the air rushing out of the vent, it's too small. Adding one or more #2 vents should cure the problem.

Sorry I'm late, BP- had to finish my taxes :-0

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Jamie Hall

Thank you all!

I knew I'd get good answers!

I'm going to try one Gorton #2 -- but, if I have the headroom, I'm going to pipe it so that I can put another on if need be... (I'm a little short of headroom, and I don't think having one sticking up in the middle of the Dining Room overhead would be appreciated...!)

SteamHead -- you should hear that Hoffman 75 roar! Quite impressive. As you say, shouldn't be able to hear them much...

At the risk of being slightly querolous, would it be possible for either boiler or vent people to relate their boilers/vents to each other for main vent type applications? Seems to me (how naive!) that there should be a direct relationship between vent capacity and boiler size -- e.g. a Gorton #2 will handle a boiler up to so and so many pounds steam/hour at 1 psi, or something of that sort.

[Deleted User]

vent size

The vent is sized for the mains, while the boiler is sized to the whole load.

A tall building with short mains would use less vent on the mains, with vents on risers, too.

A wide one story building with the same boiler, and load, would have large vents on the mains.

Noel

Boilerpro_3

However, this is a vapor system,so

all the air in the system may need to vent out the main vent down in the boiler room, right?

Boilerpro

Jamie Hall

right

There's just the one vent, sitting pretty right above the Hoffman Differential Loop (really!). Neat system -- I love it. But all the air has to come out through that vent -- which means that all that volume of steam the boiler makes (for all practical purposes) also has to come out of the vent... Whoosh!

Unknown

Jamie, on yours

The only reason that the vent is needed at all, is for that Hoffman Differential Loop to have something to push against, if it has to operate. With a vaporstat, it will never push water down far enough in the loop to operate, and pressurize the returns. With good traps and a vaporstat, you can run that with no vent on it at all.

In fact, if someone had come in and sold a boiler and a feed pump, the vent would have been a 2" pipe on a tank, and your Hoffman Loop would have been about $4.00 worth of scrap.

And then we'd NEVER figure out that header, and it's secrets. Would we?

Noel

Steamhead

On Vapor

this setup is very common. One vent for the entire system. On some systems such as your Hoffman, it was also common to use radiator traps to vent the steam mains into the dry returns.

This is why these vents need to be so big. The original Differential Loop used a Hoffman #11 vent, and the later style used a #15. Both were very large vents that are no longer made.

The Gorton #2 was designed for Gorton's long-ago Vapor system. This is why it works so well on Vapor. On a Differential Loop system, the vent will normally remain open unless the Loop blows over or a bad trap lets steam into the dry return.

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Boilerpro_3

With a 4.45 gpm input boiler...

I bet you're going to want either an open 3/4 inch or larger pipe for the vent (I'd just run it down to 6 inches off the floor in case steam ever gets to it), or at least 2 or 3 Gortons. That's a big boiler!

Boilerpro

Mad Dog

Try more than one Gorton...I did...and

the vapor gets out to the rads even faster, thus greater fuel savings. Mad Dog

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Mad Dog

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Mad Dog

Yeah, that's what i did...at first I had

one with a tee, and then I added the second one...the other main, has three....enough is enough, and i aint addin' no mo' Mad Dog

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Jamie Hall

Yup...

That's about what I plan -- except your basement is a lot neater than mine!