There are a lot of ways to heat your building. Forced air and hot water heat are the most common today, but it’s also possible to use steam. You might think that steam and water based systems would be almost the same, but they’re actually very different.
The Cheap Installation
In a traditional hot water system, water flows from radiator to radiator, then back to the furnace to be reheated and recirculated. In a steam system, you don’t need that return pipe. When the steam condenses, it’ll collect at the bottom of the pipe and drip its way back to the furnace the same way it came. The hot steam meanwhile will fill the top of the pipe.
This sort of system has traditionally been incredibly popular in tall buildings, such as the skyscrapers in New York city. Being able to use just a handful of stand pipes to provide heat to the entire structure was a massive cost savings. You could essentially build a heating system with half the pipes involved.
At the same time, steam heating could be incredibly efficient for a zone-like installation. Many radiators featured shut off valves, allowing a room’s occupant to manually manage the heat. Unused room? Shut off the valve. Too hot? Shut off the valve. It was manual work, but in the right setting, it saved on heating needs.
Once one of these radiators became heated, they would also provide heat for quite a while. Older buildings used massive cast-iron radiators. These absorbed a ton of heat from the steam and would continue to radiate that heat for hours. It could take fewer heating cycles to operate a system like this.
Despite these advantages, steam is often considered an inefficient heating set up. There are some drawbacks that have to be managed. Steam boilers often have lower AFUE ratings. It takes a lot of energy to push water from boiling into steam. And it takes even more to get enough steam to actually be useful. Consequently, you risk wasting a lot of fuel in the process. It’s hard to get a perfect, efficient burn at such high outputs.
The single-pipe system is also often as much a liability as a savings. When the condensed water travels back down, it can take energy out of the steam. The heat from the steam flows into the cooler water. In a small structure, these losses are negligible. In something like an apartment complex, they’re massive due to the scale alone. The solution is to install steam traps that separate the steam and condensation. Then you need to return the condensation to the boiler in its own dedicated pipe.
These issues are the major cause of decline in modern steam heat. It’s still popular in niche locations, such as places where there’s already a massive install base. In newer construction however, it’s become less and less popular. In the early 1900s, when fuel was cheaper and automation wasn’t quite a thing, steam was the go to way to heat and control the heat in a large building.
Why Use Steam?
The efficiency issues don’t nullify everything about steam. With modern technology, existing steam infrastructure can be upgraded to an acceptable 90% efficiency at the boiler. It’s also incredibly useful when it’s a byproduct. Facilities like power plants often use steam as their medium to drive turbines. The excess steam can be used for heating after it’s powered the equipment. Other industrial facilities that use water for cooling equipment can often generate steam that would heat their facility.
In the course of our research, we came across Penn State Steam Services. The Penn State University uses a centralized steam heating system for their campus, which provides all their heating needs and a further 20% of their electrical needs. They report about a 70% efficiency on their system. That’s not a bad figure, considering the immense size of Penn State’s campus. They report that their equipment is more efficient than utility power, and it’s something we can believe. Utility power generation is not always efficient, given much of utility equipment is decades old.
This serves as a bit of a proof of concept that in the right setting, steam is the perfect technology for modern application, if the right care is taken to install it right, and manage its weaknesses accordingly. It’s not likely to be cheaper to install these days, but it may be cheaper to operate for the right configurations.