No Steam vents?

Phil Yarbrough_2

Service tech, relativly new to steam systems. Came across one today I'm not familiar with. 2 pipe radiators, return lines small, 1/2" and 3/4". No vents on radiators. Vents on main supply lines. Float? on return above boiler.
First, should this system have vents on the radiators? Second , Is this what is refered to as"Wet return"?
Complaint was for radiators not heating. Some are getting hot but seem to be really slow.
Any input will be greatly appreciated.
Phil.

ttekushan_3

different steam systems.

A LOT of different styles of steam systems exist. You are looking at the more elaborate type with two pipes. Do not vent these at the radiator! The tail of the radiator will have some sort of steam trap on it to allow air and condensate to pass, but stop the steam. These are prone to failure over time.

Two pipe systems drain into a dry return, ie, its above the water line so air can be expelled through the return. A wet return is below the water line and filled with water as a trap against steam.

Usually a two pipe system has the main vent on the end of the dry return somewhere before it drops into the boiler. Sometimes they are augmented with single pipe style end of steam main thermostatic vents. Other times they are vented through a steam trap into the dry return.

The problems you describe sound like steam trap problems. IF that main vent is stuck or blocked, the system will heat verrrry slowly.
And review this, courtesy Hoffman Specialties:

Steamhead (in transit)

Phil, that's a Vapor system

and works like ttk says. Did you find any names on its components?

"Steamhead"

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Phil Yarbrough_2

First of all. Thanks a bunch for your input, it was a big help. Sorry for the delay, I was out doing calls late.
However, I did get a chance to look the system over again.

I found no "steam traps" on the outlet of the radiators. But I did find what I believe is a "main steam trap"? on the return just before it drops into the boiler. After some time to remove it and clean it up, I found the Name..."McAlear # 15 stamped on the top. I cleaned the outlet at the top, but it appears to have what almost appears to be lead in it at the outlet. So I don't believe that is working.
I also found a c ouple supply main vents, I tried to order some to replace them but my supplier is brain dead when it comes to steam components.
Any input on a supplier and the identiy of the return trap would be great.
Thx
Phil Y

ttekushan_3

as Steamhead said,

its a vapor system. With that in mind, look closely at the return elbows on the radiators. I'd bet that the elbows are actually orificed in some way, i.e., special elbows. They'll have a mfr's name on them. Why am I telling you this? Because high boiler pressure will cause problems and the system may even cease functioning.

1) get that boiler pressure low as it will go. Unless its got a vaporstat already, in that case set it to only about 8 ounces.

2) end of main vents should be renewed.

3) that McAlear #15 doesn't show in any of my trap lit. If it vents out the top, then its an air eliminator, probably a float type so a Hoffman #75 or equivalent is probably right.

If no air can be expelled from that "trap" at the end of the return, then thats your main problem.

And there are so many other issues that come to mind when I hear of a system like this that sounds as though its been neglected, like boiler cleanliness inside and out, operation of the safty controls, plugged pigtail, etc. It should really be gone over carefully to assure effective, efficient and SAFE operation.

Where are you located?

-Terry

Steamhead (in transit)

Does that McAlear device

have the same general shape as a main vent? If so, I found it in the 1930 ASHVE Guide- see attached. It's basically a fancy main vent. If it's something different, take a pic and post it here.

Since there are no radiator traps, it's probably an Orifice Vapor system in which orifices on the inlets (which may or may not be part of the supply valves) only allow enough steam to fill the radiators to 80% capacity at 8 ounces or so. This keeps steam out of the dry return. As ttk said, a Vaporstat is essential for maintaining these low pressures.

To size your main vents, we need to know how long each steam main is and what pipe size. For the vent on the return- how many radiators are on this system?

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Phil Yarbrough_2

#15 Air vent.

Terry, You may be correct on the orifices, I removed one of the brass elbows on the outlet of the radiators, I didn't find an orifice inside, but as Steamhead suggested they may be incorporated into the inlet. I will investigate further.
I did clean up the burners, test the low water and check the pigtail. The pressure switch is set to cutout at 2lbs with a 1.5 differential.

Steamhead, The picture you attached is the vent thats on this system. I'll attempt to find something to replace it with. I still haven't come up with anything to replace the supply vents with, I'll see is I can find a name under the years of crud. I'll measure the mains and let you know what I find.
I do want to thank both of you again very much.
In this trade we each have a specialty that were good at, I hope that someday I can add Steam boilers to my list.

BTW, I ordered one of dan's Steam books today to help in that process.

Phil Y
Ludington, MI.

ttekushan_3

ooooh Ludington's

a long walk from Cleveland. I'll bet you get a real winter there! Mmmmmmm...SteamHeat.

Always glad to help. There's a bunch of us here who love steam, and with good reason I would say.

Once you get those vents taken care of, you'll be surprised at how nicely it heats the rooms. Dan's book's probably the best single resource for steam heat knowledge.

-T

Steamhead (in transit)

You may find

that the supply house people in your area don't have a clue when it comes to steam system venting. This is inexcusable but often true. As a result, the vents now on the system may be way too small.

We can help you size your vents, just measure the length and diameter of each steam main and tell us how many radiators are hooked up to the system.

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