Why does steam percolate from below New York city streets?

Clouds of condensation are vented from manholes in Manhattan through orange and white "chimneys". This can be caused by external water being boiled by contact with the steam pipes or by leaks in the steam system itself. At least twelve steam pipe explosions have occurred in New York City since 1987. See here. Wikipedia explains.
 
horseless carriage said:
Clouds of condensation are vented from manholes in Manhattan through orange and white "chimneys". This can be caused by external water being boiled by contact with the steam pipes or by leaks in the steam system itself. At least twelve steam pipe explosions have occurred in New York City since 1987. See here. Wikipedia explains.
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That is very interesting. Thank you.
 
The best explanation I found was this:

"It’s a result of community or district heating systems...where , in cities, instead of having individual central heating systems for each building, there are heating systems that provide heat and hot water to entire city blocks ( or even an entire town)

This is achieved by having a massive boiler building, which heats water to a very high temperature, and pipes buried underground, which distribute the hot water into each building. Normally the pipes are carrying superheated steam under pressure; which then heats the water in radiators in each building via a heat exchanger.

The steam you see in streets is as a result of water from rain, and condensation, falling onto the hot steam pipes, and evaporating, causing steam.

Sometimes it might be the control system bleeding some pressure off at valves, or a leaky valve or junction."
 
Lara said:
The best explanation I found was this:

"It’s a result of community or district heating systems...where , in cities, instead of having individual central heating systems for each building, there are heating systems that provide heat and hot water to entire city blocks ( or even an entire town)

This is achieved by having a massive boiler building, which heats water to a very high temperature, and pipes buried underground, which distribute the hot water into each building. Normally the pipes are carrying superheated steam under pressure; which then heats the water in radiators in each building via a heat exchanger.

The steam you see in streets is as a result of water from rain, and condensation, falling onto the hot steam pipes, and evaporating, causing steam.

Sometimes it might be the control system bleeding some pressure off at valves, or a leaky valve or junction."
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Very interesting. Thank you.
 
CallMeKate said:
There is a YouTube channel where the guy walks the streets of NYC... nearly every day. I love, love, love it and always have. I'd never get tired of "walking with him" as he's constantly showing parts of the city. I never knew what that steam was either and needed to look it up... it always looked so strange!
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Please give us the link.
 
The steam you often see rising from manholes in New York City primarily comes from the city's underground steam system. This system is one of the largest district steam systems in the world and is operated by Con Edison, the local utility company. The steam is generated in central power plants and then distributed throughout the city via a network of underground pipes.

The steam system is primarily used to heat and cool large buildings, as well as for various industrial processes. It's an efficient and environmentally friendly way to provide energy to the city, as it reduces the need for individual buildings to have their own boilers or cooling systems.
The steam you see rising from manholes is typically due to leaks or maintenance work on the steam system. The sight of steam rising from the streets has become an iconic part of New York City's urban landscape.
 
I lived in New York City for 15 years, and never even thought about it. I probably heard information about it on news, but that was decades ago, so I can't remember what I may have heard about it. ❓
 
Even smaller cities have steam plants, often a byproduct of local electricity generation. It's another utility like water, power, natural gas, etc.

When I managed day operations in a sizable urban data center steam inputs went into the environmental control air handlers as a source of both heat and humidity. Normally cooling was more important than heating because the mainframes and servers threw off plenty of waste heat. Chillers are like big air conditioners, and often produce plumes of steam from the outdoor condensers since they can run pretty warm and environmental moisture from rain and snow boils off.

The building itself used steam in the same way.

We treated any leaks as pretty serious, but I can't say that none of NYC's steam emissions are leaks. The steam is pretty pressurized though, so I don't think those are leaks.
 
In the city where I grew up, the sidewalks downtown had these big grates that had freight elevators underneath them, leading to the basements of stores and offices so that deliveries could be made from the sidewalk. Some were solid metal and some were grates. Some had steam coming out of them occasionally.

There would be an alarm sound and the grates would slowly open up and a platform would come up flush with the sidewalk. I thought that was pretty exciting until....... I was still a child and saw a movie where the devil would come up out of one of those grates. It scared the bejeezits out of me and I gave (and still give) them a wide berth when I walk by one. I WILL NOT walk on one.
 
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