Adjustable Orifices Inside Steam System Radiator Valves

Published: January 27, 2009 - by Dan Holohan

Categories: History Lesson, Darn-Good Stories, Troubled Heating Systems

screw driver and hammer hi

Why Screwdriver Willie thought I was wrong.

In a Manhattan co-op apartment building, where the local time, mechanically speaking, is 1949, Screwdriver Willie is doing his very best to keep the tenants warm and happy while trying to maintain his own sanity. His tool of choice for this monumental task is, of course, the screwdriver.
The tenant in 3A complains about a cold radiator. Screwdriver Willie rushes upstairs, shuts off the radiator's supply valve, removes the little hex nut from the side of the valve, inserts his screwdriver and turns it. Then he puts the cap back on the side of the valve, turns the black handle all the way counterclockwise, and stands up. It doesn't take more than a few moments for the steam to move through the radiator. Screwdriver Willie holds his callused palms over the convector element and smiles "She's good now," he says. "Feel." The tenant in 3A bends with a grunt, feels the overheated air wafting off the element and smiles. "That's good," 3A says. "Thank you so much."

"You think too hot?" Screwdriver Willie asks, raising his eyebrows.

"If it is, I'll just open the window," the tenant in 3A says.

"No, it get too hot, you call," Screwdriver Willie says, wagging his finger at 3A. Screwdriver Willie doesn't want any more grief in his life than he already has. Open windows are like red flags to the members of the co-op board, who are all miserable people. The last thing Screwdriver Willie needs is to have them seeing steam heat bleeding from the many windows, like blood from open wounds.

"Okay, I'll call if it's too hot," 3A says, walking Screwdriver Willie to the door.

"Promise." Screwdriver Willie asks, knowing that 3A is a stinking liar, but at least he's now on record with her.

"Promise," 3A lies.

Screwdriver Willie goes down to his basement office and finds a note on the bulletin board outside his door. The tenant in 5A is getting a hammering noise that wasn't there yesterday. He writes that he's trying to watch TV and that the noise is making him crazy. Screwdriver Willie doesn't want to mess with 5A, who is an attorney, so he rides the elevator back upstairs and knocks on the door. 5A answers and Screwdriver Willie smiles. "Something is wrong?" he asks.

"Listen to it!" 5A shouts. The pipes are ticking. "It gets worse," 5A says, and just then, it does. Screwdriver Willie actually sees the riser move a bit. "FIX IT!" 5A shouts. "I'm trying to watch TV!"

Screwdriver Willie takes the cover off the convector, and shuts the steam supply valve. Then he uses his wrench to remove that little hex nut from the side of the valve. He reaches in with his screwdriver and turns that screw. Then he puts the cap back and reopens the radiator. The knocking stops for a moment, and then gets worse. 5A shoots Screwdriver Willie a look that could scratch glass. Screwdriver Willie backs toward the door. "I need to get tools. I'll be back," he says and scoots from the apartment.

The elderly tenant in 5B opens his door and stops Screwdriver Willie on his way to the elevator. "It's too cold in my apartment," 5B says. "Can you look at it while you're here?" Screwdriver Willie goes in and repeats the procedure he performed in 3A. When he is done, he wags his finger. "Don't open the window," he warns 5B.

"I won't," 5B lies.

Screwdriver Willie didn't call me on the telephone. Superintendents rarely do. No, the tenant in 8C called me on the telephone. His name was Stewart. Everyone in America who has a heating problem has my telephone number.

"The noise is making me crazy," he says. "I live in a co-op apartment building in Manhattan and unless everyone in the building is having the exact same problem, no one is willing to pay for the fix."

"What type of heating system do you have?" I ask. "Is it steam?"

"Yes," 8C says.

"It's probably your steam traps," I explain. "That's the most common cause of banging problems in an apartment building. No one wants to take care of the steam traps so the steam just works its way into the return lines. Those return pipes are much too small to handle low-pressure steam, and that's when the problems begin."

"What's a steam trap?" 8C asks.

"It's a small, automatic valve that sits on the pipe at the bottom of the radiator," I explain. "When a trap dies, you don't read about it in the New York Times. It's just dead."

"Will you talk to my super?" Stewart asks. "He's right here. His name is Willie."

"Sure," I say.

"Hello?" Screwdriver Willie says.

"Hello. I'm Dan."


"Hello. Do you know what a steam trap is?"


"What type of steam traps do you have on the radiators? Can you read the name?"

"We no have steam traps," Screwdriver Willie says.

"But you do know what they are?" I ask. "They're on the pipes by the outlets of the radiators? Could you look?"

"We no have 'em," Screwdriver Willie insists.

"Did someone take them off?" I ask.

"No. We never have them."

Now, just so you know, in any two-pipe steam heating system, there has to be something to stop the steam from going through the radiators and into the returns. It's usually a steam trap and steam traps are prone to fail over time. The nature of the people who live in co-op apartment buildings, regardless of location, is to ignore steam traps until the bricks fall from the facade as a result of water hammer. Because of this, some of the Dead Men didn't install steam traps. They installed orifices instead.

An orifice is nothing more than a little hole that you put in the way of the steam. It usually looks like a washer, and you'll find it either in the supply valve or the return elbow of each radiator. Air and water will pass through the orifice but steam has a tough time squeezing by. Oh, it gets through, but in an orderly way. The Dead Men who sized the orifices figured out how to match them to the size of the radiators. The idea was to let the orifice pass about 80% of the total volume of steam that the radiator could condense. Done properly, all the steam condenses inside the radiators and none of it enters the return lines.

"What sort of supply valves do you have?" I asked Screwdriver Willie.

"The kind for the screwdriver!" he says. "The tenant want heat, I use screwdriver!"

"Do those valves have a nut on the side?" I asked. "You have to remove the nut to put the screwdriver in?"


"And did you use the screwdriver on the valves?"

"Yes! They all want heat!"

So I took a deep breath and gave some thought to how I was going to break the bad news to Screwdriver Willie. You see, the American Radiator Company used to make this system they called the Model K. Rather than have their contractor customers deal with all different orifice sizes, they put a small threaded rod inside their supply valves. Move the rod and you change the size of the orifice. One size fits all radiators, but you have to set them up right. You remove the cap on the side of the valve and turn the threaded rod with a screwdriver but just so many turns, and based on the size of the radiator. You have to do it right because if you let too much steam into the radiator the steam will pass into the returns. And when you have steam in the returns, the air can't get out. And when the air can't get out, the radiators can't get hot. Oh, and you also get lots of water hammer.



"Tell me you didn't turn all of those screws."

"But . . . I did! They all want heat."

When they're all wide open, those orifices might as well not be there. I ask Screwdriver Willie to put Stewart back on the phone and I tell him the bad news. I explain that someone is now going to have to go around to every radiator in that building, figure out each radiator's capacity in square feet EDR, and adjust the American Radiator Company's Model K variable orifice valves, just as the Dead Men did on Day One. This will probably take a long time.

"Who pays for this?" Stewart asks, as though he is expecting me to open my wallet.

"That's a sociological question," I said.

And it was, because not enough people in this particular co-op apartment building were miserable enough to pay for what needed to be done. That's the nature of co-ops. Only miserable people band together to get things done.

Stewart asks me to hold on. I hear him tell Screwdriver Willie the bad news. I hear Screwdriver Willie tell Stewart that I don't know what I'm talking about. They go back and forth like this for a while as I wait on hold, and then I hear Screwdriver Willie say, "The people want heat! I use screwdriver, they get heat! I no can use screwdriver now to take away heat! This man you call on the telephone, he stupid!"

Stewart comes back on the phone to tell me that he thinks I'm wrong. But he does thank me for my time.

Which counts for something, I suppose.

And by the way, the same thing happens when you take the orifices out of any other type of old steam systems. Try it. You'll see what I mean.