Further mysteries of the 1906 K-M-C Vacuum System

Steamhead (in transit)

is a vacuum gauge. It's likely calibrated in inches of mercury. Somehow, maybe from condensing steam as the system warms up, it forms a vacuum that the gauge can read. As the pressure builds it returns to zero.

I'd put a Vaporstat on your system, to keep the pressure below 1 pound.

Steam won't reach the vent on the air line unless a radiator vent fails. But it doesn't hurt to "wear a belt AND a pair of suspenders".....

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Michael_37

No pressure and that seems wrong

Thank you all so much for your help with my steam heat system. In response to all of your help on another thread (http://forums.invision.net/Thread.cfm?CFApp=2&Thread_ID=59970) I have added air venting and lowered the pressure. Now my house heats! Hooray!

Unfortunately I am still trying to understand this system and there are some other problems. Please forgive my ignorance about plumbing and heating -- I am a homeowner and I am trying to learn this stuff. I now understand that I have a K-M-C 1906 "Non-Mechanical Vacuum System". It is a modified one-pipe steam radiator system where instead of vents in each radiator, thin air return lines move all air venting to the basement. The system was designed so that the overall pressure could be closely controlled, allowing steam to be produced at different temperatures by varying the pressure.

Gerry Gill sent me this patent that was very helpful. I will refer to the main diagram to describe my troubles.
http://forums.invision.net/Attachment.cfm?STEAM_HEATING_PLANT.pdf&amp;CFApp=2&amp;Attachment_ID=35591

My heating/plumbing contractor came out and replaced a leaking return main (Gerry's diagram calls it "the bleeder end of the steam-supply pipe below the water line" -- the main near "M") and two other leaking radiator valves. He now admits that also removed the connection pipe labeled "M" on the diagram because he didn't see any reason for it. That was the unsolved mystery in my last thread.

A long time ago someone removed the original mercury tank that was used to vent air (on the diagram it could be connected to C?) It was replaced with a Dunham's Air Eliminator at about the same location (C). This appears totally clogged and extremely rusty and it doesn't do anything.

So that means when my contractor fixed the leaks and removed M, there was no way for steam to move through the system. There apparently have been no working vents for some time (except the leaks). I think connection M was allowing some circulation because of the pressure differences in some parts of the system vs. others. (Not sure.)

However, now that "M" has been removed and an air vent has been added at about "I" on the diagram (either "I" will do), I cannot build pressure in my system. The air vent is great because it allows my system to heat at all. But now I can't build any pressure.

I think I understand why. "I" is not a steam main, it is an air return line. Steam never reaches it. I opened that pipe to the atmosphere and ran the system and I got only a few drops of water out. So I think that means that the air vent he put on it will never close. If that vent is always open, the system is can never be pressurized, right?

That means that with an air vent on that pipe the boiler will never reach my cut out pressure on the pressuretrol. So the burner never cycles. This seems like a bad idea but I don't know enough to be sure. The way the system is working now, a call for heat from the thermostat will produce continuous firing of the boiler. Isn't that a bad idea? Or is it OK?

I have ordered all of Dan's books and I found several very old books that mention my K-M-C system on Google Books but I am still having a hard time working out what is happening and what to do about it.

Last note but also important: the escaping air from the new air vent is VERY LOUD and it vents all the time whenever the system is operating.

Stuck again and hoping someone has ideas.
Christian

Charlie from wmass

Christian have you sized your heat load, found the square feet of steam the radiators require? It may be the boiler is sized for insulated pipes and hybridizing a system can lead to issues.

Steamhead (in transit)

You should be OK

as long as all radiators heat up quickly and more or less evenly. The steam is being condensed as fast as it is generated. This tells me that the boiler is sized about right.

A burner that starts and stops frequently wastes fuel and wears out more quickly.

What kind of vent was installed on the air line?

"Steamhead"

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nicholas bonham-carter

if it's too loud

congratulations on being able to understand that patent!
my children used to say [about music from their rooms] "if it's too loud you're too old" [in jest].
the loud vent noise could indicate too much pressure.
eventually all the air in the system will have been pushed out, and you would then have steam coming through the vent; which is perhaps unable to close because of high pressure.
are you really sure of your operating pressure? a good low pressure gauge rated in ounces will tell you if pressure is the problem.
maybe some of those air vent pipes have blockages in them which is another complication.
keep up the good work-you will soon qualify to wear the "dead men" hat.--nbc

Unknown

I'd just wait for Dan's books and keep tracing out the system. I'd also make a schematic drawing of all the piping and all components. It sounds to me that your system has been "butchered" over the years and some parts either missing or mismatched .
You seem to have absorbed the KMC patent drawing very well so I'm pretty confident that after reading "The Lost Art of Steam Heating (which mentions the KMC system on page
267) you'll be in a better position to explore what parts and modifications are necessary to fix/update your system. In the mean time while it maybe noisy at least you don't freeze to death!

Michael_37

my low pressure gauge is 102 years old

Okay. This is the confusing thing about the K-M-C system though. (For me, anyway.) As far as I can tell steam will never reach the vent. Since the K-M-C has these air return lines and that is what is being vented, the steam is always stopped by steam trap long before the vent. Since the contractor removed the only "M" connection there is no route for steam to travel from the mains to this vent. Even if some steam makes it through a steam trap into the air return (e.g., because a trap failed?), the air line is very long and cold and not insulated.

Funny thing about pressure gauges. I have two. One was installed 17 years ago with a new boiler. It is a 30 PSI gauge and it works. The other is a 102 years old and is original. It is rated in 30 somethings. Everyone who worked on the system assumed it was broken because it always read 0. But in fact ... drumroll ... it is a low pressure gauge for my low pressure system and I think it works. If you watch the boiler the antique gauge climbs up through 30 then it can't handle the pressure and goes back down to 0 and the new gauge (after a but) starts to move up from zero. No idea what the units are. The gauge doesn't say.

Here is a picture of my low pressure gauge:
http://www.flickr.com/photos/niftyc/3018000034/in/set-72157608801023873/

So I think it is not a pressure problem. There is no pressure -- it is all going out the air vent. If I remove the air vent and cap the pipe then I get pressure and the pressuretrol shuts off the burner when it is supposed to. (But then the steam doesn't move.)

Christian

Michael_37

Hoffman... did I do wrong?

The heating contractor and I had a disagreement about this. He wanted to use a Hoffman vent instead of the Gorton No. 2 you recommended. His argument was basically that they are the same thing and the Hoffman is the one he has in his truck and is familiar with. It didn't seem right to leave an open vent pipe and I do not fully understand this system or know anything about steam so I caved in and took the Hoffman. Did I do wrong?

Michael_37

You're right Rod. I won't make any sudden moves. Now that I have a heated house this thread has A LOT less urgency than the one I started last weekend, and I have this bulletin board to thank for that warm house.

I think I am now very interested in steam heat though and this system is itching at me. I want to figure it out.

Christian

Steamhead (in transit)

Well, you can hear it hiss

so that tells me it's too small. Is it the 4A, that looks like a silver bullet? Main vents are NOT the same, which is why we make such a big deal of them.

A main vent at M will speed up steam distribution still more. Measure the length and diameter of the steam main from the boiler to M and we can tell you what you need.

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Michael_37

It is a Hoffman No. 75


I guess the thing I am worrying about is that my pressure controls on the boiler now don't do anything and that seems wrong. But I don't understand the system obviously.

I mean that the burner on my boiler seems (?) now to be controlled only by my thermostat. If the thermostat calls for heat then the burner runs continuously until the thermostat's temperature is reached. No pressure gauges show any reading, no pressure builds in the system. The Hoffman vent hisses loudly for a long time as air escapes, then it is briefly quiet (but still venting) as the various steam traps open and close, then if the thermostat shuts off after a little while it hisses loudly again as air goes in.

The contractor didn't just unscrew the linkage at "M", he fabricated a new very long iron main without a joint there.

All of this just happened. Let watch it for a while and see how it does. Maybe I am just not used to having any venting noise at all, since the earlier problem was no venting.

Christian

Steamhead (in transit)

But since it's hissing

there's more air to be vented than it can handle. So it's slowing the process. A Gorton #2 will vent about 3-1/2 times what a #75 will.

It is possible to drill and tap a hole for a main vent at or near M, so the new pipe would not have to be disassembled.

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Michael_37

Aha!

Now that you say that it all makes sense.

I found a delightful book called "Principles of Heating: A Practical and Comprehensive Treatise" by William Snow (copyright 1907). The advantage of this K-M-C system is that it is supposed to operate at a vacuum. The original Mercury seal is not just a vent but a one-way vent (which I presume the Hoffman No. 17 is not).

You raise the system pressure to 2psi once a day (the maximum pressure recommended). This expels all air. Since the air can't return through the one-way Mercury, as the steam condenses you produce a vacuum.

The change in pressure lowers the boiling point. That means if you know how to work this thing you can produce cool steam by manipulating the vacuum. A table shows me how to use this system to produce steam at 101-212 degrees. The system was designed for Illinois, so that our "mild" winter temperatures of 30-40 degrees can be managed. With low-pressure steam "considerable saving in fuel may be effected...also thus avoiding overheating."

Of course this system doesn't work that way now.

Christian

Unknown

LOL..Yes... it's darn hard to find a heating supply company that sells mercury these days!!

One thought- does the pipe near where the vent is get hot?
Be careful don't get a steam burn !

gerry gill

Do what Steamhead says,

and put more main vents on your vent pipe..you don't need pressure to heat with..if you can heat with no gauge movement then life is good..think of pressure as a backpressure from lack of venting..and you should make sure you get ''paul''vents put on all the rad that don't have them..

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Michael_37

what is a \"paul\" vent?

Okay, it looks like I don't need any pressure to heat with. Maybe I will be able to build pressure when it gets colder. I just worried because the burner runs continuously in the morning for over an hour when the thermostat kicks in. If that is fine than I am fine.

I think I am going to hold off on the vaporstat until I see what happens later this winter. I am still smarting from the steam main replacement.

Thanks Gerry but what is a paul vent? You mentioned this before. I googled and googled but can't find this term. I'm pretty sure I currently have no vents on any radiators. The K-M-C has only one vent. All radiator venting is piped to the basement with air tubes. One Hoffman No. 17 is currently venting everything in the system. No vents have been added that I can find.

Christian

Unknown

Christian-
Here's the link to Hoffman Specialty

http://www.hoffmanspecialty.com/HS-Overview.asp

Go to the menu and click "Products"
In the Parts window select "Residential Parts catalog"
That should take you to a page where you can find the valve you're looking for.

Hoffman and others are owned by ITT and the website is rather screwy. It is easy to get into an area that has nothing to do with what you are looking for.

I know nothing about the Paul System other than what I read about it in "The Lost Art of Steam Heating" (page 249) The "Steam Pros" can probably give you a idea the valve you need. Perhaps you can find some numbers on your old radiator valves that would help.

This Steam Heating is fascinating! It really gets addictive. I rather envy you having a unique steam system. Mine's just an ordinary single pipe system.

Steamhead (in transit)

It's a radiator vent

that hooks up to an air line, just like you have now. The Paul system was the best-known air-line system, so replacement vents are often called Paul vents.

"Steamhead"

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gerry gill

one of these

technically a hoffman #3...same as the fulton sylphon you have.

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gerry gill

one of these

technically a hoffman #3...same as the fulton sylphon you have.http://www.hoffmanspecialty.com/pdf/hs900/HS900-3474.pdf

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