Dealing with an Old Two-Pipe, Air-Vent Steam System

So my buddy gets this large, prestigious job in Manhattan, which is going to make him even more money in the years to come because billionaires who build such city houses are jealous of each other. They all want to own the mechanical artists that the other billionaires have. There’s a tradition for this.

When Mr. Vanderbilt had The Breakers, his 65,000-square-foot summer cottage in Newport, RI, built, he included piping for hot and cold city water, sea water and rain water. I know this because I once stared at all those pipes one day and scratched my head. You see after construction, Mr. Vanderbilt had all the blueprints and plans for the cottage burned so no one could ever do again what he had done. So there.

My buddy, who is a very successful New York City contractor, got this job from the general contractor, who had been working with a Long Island plumbing-and-heating company, because, he told my friend, “Long Island plumbers don’t know how to do vertical heating. The houses on Long Island are all horizontal. Long Island guys are great at horizontal heating, but I can’t afford to mess up on this one. That’s why I want you. You guys do vertical heating.”

So my buddy, being a smart man, smiled and agreed. Vertical heating? Absolutely! Which proves, once again, that if you set yourself up in the right place at the right time, and you are willing not to argue with people who are sometimes ridiculous, life will smile upon you and you will come out of the deal smelling like new cars and cinnamon buns.

As did my buddy.

This was all on my mind when I visited this 1901, steam-heated office building on Fifth Avenue in Manhattan. A friend had asked me to take a look because her company was working on greening the building. “Greening,” in case you don’t know, is a 21st-Century way of saying, “Let’s see if we can get rid of the overheating, underheating, high fuel bills and banging pipes in this old steam system.” But first, she had to figure out what she was dealing with because this building had some very serious vertical heating and more than a hundred years worth of hands touching it.

It sounded like it held a good story, and the place is just four blocks from the house where Teddy Roosevelt was born, a place that was on my Bucket List, so I said I would take a look.

Teddy was born in a brownstone building on East 20th Street, just off Park Avenue and the 45-minute tour is free. I was a bit disappointed to learn that the building that is there now is a 1920s recreation of the original, which was knocked down at the Turn of the Century to make room for a store. There are fireplaces and 1920s steam heat in the place now, nothing that grabbed me by the lapels, but it was good to listen to the docent go on about the history of the neighborhood. When Teddy lived there, this neighborhood was a suburb of Manhattan. Imagine that. And then the stores came and the rich folks all moved further uptown.

So when I arrived at the office building, which was once all stores, I had the neighborhood history in mind and I was able to see the place through time and imagine what once was. That helps when you’re looking at a building that many have messed with over the past 111 years.

My friend was curious about the steam system in this building because it was both one-pipe and two-pipe steam. She told me that the building was originally 10 stories tall and that’s where the two-pipe steam is, but then, very early in the last century, they added another three stories to the place, and these floors all had one-pipe steam. Could they work together? Yes, they could, and we set out to take a look.

We get into the elevator and begin with a whisper-quiet law office. A woman in an expensive suit meets us and brings us into the room where they take depositions. “Is it noisy in here?” I ask. “I mean the pipes, not the clients.”

“Oh, yes,” she whispers.

“When is it noisy?” I whispered back because the when and the where are very important things to know when looking at an old steam system.

“On Monday mornings. It’s crazy on Monday mornings.”

“Is it hot in here?”

“Like you can’t even stand it,” she whispers through clenched teeth.

I’m seeing the problem and asking the questions to confirm what I already suspect. Thermostatic steam traps for radiators arrived in 1905. This building went up in 1901, so the builder used a two-pipe, air vent system for the first phase. The supply main is two-inches in diameter and rises from the basement to the top floor. The return main is 1-1/2-inch and stands right next to the supply main. Off of these two vertical pipes are the radiators, set like rungs on a ladder. This system is the missing link between one- and two-pipe steam. They used it in tall buildings at the Turn of the Century because a building this tall wouldn’t work well with one-pipe steam if the supply came up from the basement. All the condensate draining back down that tall riser would kill the steam trying to make its way up. So they put air vents on all the radiators and drained the condensate from each radiator through a return riser. They would make that riser one size smaller than the supply riser so the steam would favor the supply on start-up, but once the system was hot, there was going to be steam in both the supply and return risers, and that was perfectly normal.

The law office was overheating because the radiators were sized to heat the space when they had 1901, single-pane windows. Now they had modern windows and they were gagging. So a contractor installed thermostatic radiator valves on the supply side of all the radiators. The steam looked at those TRVs, shrugged and used the return lines to overheat the radiators. Steam is like that. It’s just looking for an air vent.

The system had a Heat Timer that lowered the temperature over the weekend, so when the steam returned on Monday morning, it hit tons of cold steel and made lots of condensate, which it knocked around like a demolition derby. After the pipes got hot, there was less condensate and less banging, but there was still that oppressive heat. I explained that the supply-side TRVs weren’t going to work. They had to use the sort of TRV that went between the air vent and the radiator. Either that or they would have to convince all the other tenants in the building to install supply-side TRVs and thermostatic radiator traps. Good luck with that.

We went from floor to floor and found similar situations. This is a building where the companies buy the floors that they’re on and then never speak to their neighbors. They’re all sharing an antique steam system and they think they can do what they want with just their part of it. They can, of course, and they do, but it won’t work because of the physics. It’s tough arguing with physics.

The one-pipe radiators on the top three floors connected off the supply riser and drained back into it. There were acres of people working quietly at computers on these floors. In some of the spaces, the architects had the heating contractors move the radiators between those two windows way over there. Having the radiators in the middle of the windows was aesthetically pleasing to the eye, but the horizontal pipes running to those now-far-from-the return-riser radiators either didn’t pitch back toward the return riser, or pitched the other way, so they were arguing with gravity. I asked the quiet people at the computers if their radiators were noisy. They all winced.

Downstairs in the boiler room, I checked the pressuretrol and found the system set to run between 5-1/2-psi and 7-1/2-psi, which is about five times higher than it should be, and well beyond the operating pressure of one-pipe steam air vents. That means that the steam pressure was able to lock closed the air vents after the first cycle. That leads to very uneven heating.

The superintendent will respond to those problems by raising the pressure on the boiler even higher. He does this because he can, and because he is not a student of vertical heating.

He probably lives on Long Island.