How does NYC heat work?

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asked May 16 in Other-Environment by FGjple (880 points)
How does NYC heat work?

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answered May 16 by GrahamPolk (3,950 points)
The heat in NYC is most often by boiler which creates steam to heat the inside of buildings in NYC.

Although some apartments may use natural gas or electricity to heat with but the majority of buildings in NYC are heated by steam and boilers.

Con Edison's Steam Operations is a district heating system which carries steam from generating stations under the streets to heat and cool buildings and businesses in Manhattan.

Some New York businesses and facilities also use steam for cleaning and disinfection.

The velocity of steam in a pipe is between 6,000 to 12,000 fpm, although some lower pressure heating systems normally have lower velocities.

The reason steam heat is so loud is because of the water which is hitting the metal interior of the pipe or the radiator at very high speeds.

Knocking radiator sounds are generally a sign of trapped water or air in the system.

When either gets stuck, steam is prevented from moving through the pipe into the radiator.

This pressure build up can make a loud knocking or banging noise.

Boilers do last longer than furnaces.

The average lifespan of a boiler that is properly maintained is around 30 years and the average lifespan of a furnace even if it's properly maintained is between 15 to 20 years.

Natural gas furnaces also run the risk of valve leaks, which can cause serious health issues.

In contrast, the radiant heat from a boiler system is much more comfortable than forced air from a furnace.

These units are also less noisy, more energy efficient, and create better air quality inside your home.

The difference between steam and condensate is the condensate is the water droplets and water that appears on the outside of pipes, surfaces etc.

Steam is the vapor of boiling water that creates pressure and forces.

Condensate is the liquid formed when steam passes from the vapor to the liquid state.

In a heating process, condensate is the result of steam transferring a portion of its heat energy, known as latent heat, to the product, line, or equipment being heated.

The temperature at which a boiler condensates is between 80 F to 120 F degrees.

Boiler condensation is caused by the flue gas falling below the dew point.

Flue gas will form and condense on a heat exchanger and in the boiler stack when it falls below its dew point, and this occurs when the return water temps of the system are around 135°F.

The vapor of the flue gas undergoes a phase change into a liquid which is now acidic with a pH typically between 2–5.

A condensing boiler uses condensing technology to make better use of the heat it generates.

When a fuel such as gas or oil is burned, gasses are released via a flue.

In a non-condensing boiler system these gasses would be released into the atmosphere and their heating potential would be lost.

The only way to avoid sustained flue gas condensation is to monitor the boiler's inlet water temperature and react to that temperature by limiting the rate at which heat moves from the boiler to the distribution system.

Furnace condensate is not a toxic liquid; however, it is an acidic solution that consists of water, carbon dioxide, nitric acid, and, in some cases, traces of metal, mold, and mildew.

This condensate is corrosive and has to be neutralized before getting drained into the wastewater system.

A typical hour-long operation of your boiler may produce around 2 or 3 liters of the condensate water waste.

This waste generally gets released in 300ml increments, and is often the reason you might hear water traveling through your pipes during intervals.

If you have a white plastic pipe coming out of the bottom of your boiler you have one of these.

Another way to tell is your flue (exhaust) if this is plastic it's a condensing high efficiency boiler, if it's all metal a non condensing boiler.

The lower the return temperature to the boiler the more likely it will be in condensing mode.

If the return temperature is kept below approximately 55°C (131°F), the boiler will be in condensing mode and working at its most efficient.

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