New York City steam system

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Steam vapor being vented through a typical Con Edison orange and white stack on Seventh Avenue at West 22nd Street. Steam vapor such as this can be caused by a leak in Con Ed's steam system – which heats and cools buildings in Manhattan up to East 89th and West 96th Street – or by cooler water contacting the outside of a steam pipe.[1]

The New York City steam systems include Con Edison's Steam Operations, and other smaller steam systems that provide steam to New York University and Columbia University. Many individual buildings in New York have their own steam systems.

Con Edison’s Steam Operations[edit]

Con Edison's Steam Operations are a district heating system which takes steam produced by steam generating stations and carries it under the streets of Manhattan to heat and cool buildings and businesses in Manhattan. Some New York businesses and facilities also use the steam for cleaning and disinfection.

The New York Steam Company began providing service in lower Manhattan on March 3, 1882.[2] Today, Consolidated Edison operates the largest commercial steam system in the world (larger than the next nine combined).[3] The organization within Con Edison responsible for the system's operation, known as Steam Operations, provides steam service to over 1,700 commercial and residential customers in Manhattan from Battery Park to 96th Street uptown on the west side, and 89th Street on the east side of Manhattan.[4] Roughly 24 billion pounds (11,000,000 t) of steam flow through the system every year.[1]


Steam provides heat and cooling to many buildings in New York. The steam system also provides humidity to art museums, steam cleaning for restaurants to clean dishes, and other uses.[3]

Environmental effects[edit]

Approximately 30% of the ConEd steam system's installed capacity and 50% of the annual steam generated comes from cogeneration.[5] Cogeneration and Heat Recovery Steam Generation (HRSG) significantly increases the fuel efficiency of cogenerated electricity and thereby reduces the emission of pollutants, such as NOx, sulfur dioxide, carbon dioxide, and particulate matter, and reduces the city's carbon footprint. Con Edison is promoting the use of steam for cooling in the summer months, something that can be accomplished with the installation of absorption chillers.[6] Such trigeneration systems reduce peak electrical loads and save construction costs associated with expanding electrical infrastructure.

Clouds of condensation can occasionally be seen rising 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.[1]

At least twelve steam pipe explosions have occurred in New York City since 1987.[7] The most recent incident was the 2018 Steam Pipe explosion which occurred in the Flatiron District and forced the evacuation of 49 buildings.[8][9] The explosion released concrete, asphalt, "asbestos-containing material" and mud into the air. The asbestos cleared out of the air to safe-level.[10][11] A previous incident was the 2007 New York City steam explosion, and another on June 28, 1996, at a plant on East 75th Street.[12]


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Systems for individual buildings[edit]

In New York City, many individual buildings use either a hot water or a steam system for heating, and have a boiler in the basement. A boiler is an enclosed vessel or tank that heats water using oil or gas.

A steam boiler will usually keep the heat at 180 °F (82 °C), then when the thermostat indicates that heat is needed, it will increase the temperature to above the boiling point, 212 °F (100 °C). This will cause steam, which is lighter than air, to rise through pipes into the building's radiators.

While most heating systems are controlled by a thermostat which monitors the inside air temperature, many of New York's steam heating systems are controlled by the outdoor air temperature, which is far less efficient.

Steam heat has both advantages and disadvantages. It is noisier and less efficient than hot water heat, but it delivers heat more quickly and uses less electricity, since it doesn't need a circulator pump. Steam systems can produce more uneven heat, and the radiators are generally larger.

The noise known as “steam hammer”, which sounds like hammering on a pipe, is caused when water condenses and is trapped in a horizontal section of pipe where it cannot drain back to the boiler. When the system is next turned on, this water is hurled through the pipes by the steam pressure, creating a loud bang.[13]

See also[edit]


  1. ^ a b c "Steam operations FAQ" Archived 2016-08-11 at the Wayback Machine on the Con Edison website
  2. ^ "A Brief History of Con Edison". Con Edison. Archived from the original on 2006-03-12. Retrieved 2014-05-04.
  3. ^ a b c Moyer, Greg (9 October 2014). "Miles of Steam Pipes Snake Beneath New York". Retrieved 20 July 2017 – via
  4. ^ "Steam Energy" (PDF). Con Edison. Retrieved July 5, 2017.
  5. ^ "Con Edison Steam Long Range Plan 2010-2030" Archived 2010-12-07 at the Wayback Machine, p. 69
  6. ^ Benefits and Case Studies of Hybrid Cooling Using Steam Archived 2007-10-08 at the Wayback Machine, Consolidated Edison
  7. ^ Belson, Ken and DePalma, Anthony. "Asbestos and Aging Pipes Remain Buried Hazards", The New York Times (July 19, 2007).
  8. ^ WRAL. "28 buildings evacuated in NYC steam pipe explosion ::". Retrieved 2018-07-19.
  9. ^ Brassil, Gillian (2018-07-19). "Asbestos found at steam pipe explosion in Manhattan's Flatiron District". CNBC. Retrieved 2018-07-21.
  10. ^ "Steam Pipe Explosive Event: Frequently Asked Questions (FAQs)" (PDF). 19 July 2018. Retrieved 20 July 2018.
  11. ^ "Mayor de Blasio Delivers Update On Manhattan Steam Pipe Explosion". The official website of the City of New York. July 19, 2018. Retrieved 2018-07-21.
  12. ^ Raffa, Frank. "Con-Ed Blows Off Some Steam". Retrieved February 20, 2014.
  13. ^ Boiler 101: typical NYC residential heating system The bottom of the barrel: How the dirtiest heating oil pollutes our air and harms our health, Environmental Defense Fund, M.J. Bradley & Associates LLC, Chapter 2

External links[edit]