How They Heat The Dakota
Imagine. . .
I was standing on the roof of the Dakota Apartments, looking out at New York’s Central Park across the street and thinking about John Lennon who lived and died in this building. I was up there on the roof because the circa-1880 steam heating system was getting a new boiler and the engineer and architect in charge of the project had some questions about the system piping. I jumped at the opportunity to get inside this famous place, which I have looked at all my life.
Most of New York City still heats with steam, a 19th Century technology that hangs on like an old uncle. The steam races directly from boiler to radiators without benefit of any sort of heat exchanger. The steam condenses inside the radiators, giving up its latent heat to the air in the room. The water then flows by gravity back to the boiler. Children living with these systems (I was one of them) learn early on that you may touch the radiators if you’d like, but you’ll probably only do that once.
In most buildings, the only control available to the tenants is the window. We call these double-hung zone valves. It’s quite wasteful, of course, but no one with steam heat in a big building in this country pays directly for the heat, so few consider the cost, or the waste, and besides, the valves are often frozen in place. So there you are.
And let’s face it; most of us don’t worry about the waste because, in America, there are no heating police. It’s not like it is in Europe. We’re allowed to own heating systems that started out in the 19th Century burning coal, were converted to fuel oil in the 1930s, and then, perhaps, to natural gas in the ‘70s. These boilers are as drafty as canyons and as large as small apartments, and many Americans, and certainly most New Yorkers, think this is normal.
The radiators in the Dakota Apartment are from the 1870s. A man named Reed invented them. Each radiator has several rows of capped vertical pipes, and each pipe is sealed at its top. The pipes press into an iron base and the steam rises within each, displacing the heavier air, which works its way from pipe to pipe and leaves the system through a special vent at the end of each radiator. This vent from the 1880s contains a cork, which swells when steam reaches it, closing the vent to the steam. Each of these vents has a small pipe that travels down though the building to what once was the steam-engine room. The steam engine is long gone, but it once provided electricity for the building. They used the waste steam from the engine to heat the radiators, and when other buildings appeared as neighbors to the Dakota, the owners of the Dakota sold power and steam heat to them. The Dakota was one of the world’s first co-generation systems.
I know this because I spend most days reading old books. I love this stuff. I spent part of my youth in New York City, skating on the pond in Central Park and looking up at that magnificent old lady of a building. I have an archival photo of people skating on that lake in the 1890s, when the Dakota was the only building around. People come and go, but the buildings stay. And in America, so do the heating systems, and this makes life interesting for those of us in the business because we have to understand the newest technologies, and these 19th-Century systems as well.
My father’s father, James Holohan, left Kilkenny in Ireland at the turn of the century and came to America to shovel coal in a public bath. He was a big man and he and Mary had a bunch of kids before he died far too young. My father went to war in 1941 and came back to work in a plumbing supply house in New York City. We lived across the street and my earliest memories, and they are sweet, are of playing on the loading dock of that place. I went to work with my father in 1970, after he had moved to a manufacturer’s representative, and I treasure every moment of those years. I learned much.
These days, there’s a large horizontal, fire-tube boiler in the basement of the Dakota. It makes low-pressure steam by burning Number 6 fuel oil, which has the thickness of molasses. The oil waits in an enormous tank in the basement (about 6,000 gallons worth), and they have to heat this thick oil in a shell-and-tube heat exchanger before they can move it to the burner. Six oil is cheaper than Number 2 oil, which is why they use it. No one wants to pay too much for anything in America.
Now here’s the best part about the Dakota: Each radiator has two pipes. The supply pipe is 1-1/2-inchs in diameter and the return pipe measures 1-1/4 inchs. There is a valve at each side of every radiator and no other controls (except for the window). The steam enters through the larger valve and the condensate leaves through the smaller valve. When the tenants (all of whom are crazy-rich and variously famous) are too hot, they call downstairs and one of the heating guys will ride the service elevator to their apartment and close the radiator valves. The heating guy then returns to the basement and waits for the next call, which invariable has to do with the same fabulously wealthy tenant being too cold. The heating guy will make the trip upstairs, but this time to open the valve. We call these people two-legged zone valves.
So that’s Manhattan and much of it is like this, but things are changing, albeit slowly. About a mile and a half south of the Dakota is the Hearst Tower, which was the first skyscraper to rise in New York City after September 11, 2001, and the greenest building around. Hearst uses outdoor air for cooling and ventilating during most of the year, and this practice delivers a 22-percent savings in energy use and carbon dioxide emissions (there are no double-hung zone valves in this beauty). The building also has radiant-floor heating in some areas, and motion sensors throughout to control lights and machinery. They collect the rainwater from the roof and store it in a 14,000-gallon tank in the basement. They use this water to replenish evaporation from the building’s air-conditioning system, and to water the indoor and outdoor plants. And some of that collected rainwater goes to the three-story waterfall in the atrium lobby. This waterfall helps cool the place. It’s breathtakingly modern, green, and efficient and it sits as an example of what can be, and must be in our American future.
I was standing on the roof of the Dakota Apartments, looking out at Central Park and Yoko’s “Imagine” memorial to John Lennon. I was with the building’s architect and he walked me over to these cast-iron bowls that sat on pipes atop all the ventilating shafts. Those pipes ran down to the basement. “Any thoughts on what these are for?” he asked. I looked and thought about what I had read, and then I realized that these bowls were the collectors for the rainwater that flowed to a long-gone tank in the basement. You see the Dakota once had hydraulic elevators, and these elevators ran on rainwater. They stored the rain in those days, just as the Hearst Tower is storing it today, and all of this is connected through time. And so are we.