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Steam vs. Hot-Water Heating

notre dame power plant

It was a real battle in the early days of heating. There were steamfitters and then there were the hot water people.

I have a wonderful old ad from Honeywell that goes back to 1909. The headline reads, "Put this sign up." There's a well-dressed man taking down a sign that reads, "Steamfitter" and he's putting up a sign that declares "Heating Expert." The ad copy goes on to explain how Honeywell's new hot water system will reduce the coal pile and increase comfort and efficiency. It also states that there are over 14,000 of these modern systems now in place, and I believe that because I've run across quite a few of those Honeywell hot water systems. They're still in service, and they're a bit scary because they included the Honeywell Heat Generator as one of the system components. This old cast-iron device had just one moving part, that being a pot of pure mercury. The Heat Generator gave the heating professionals who used it the ability to run an open-to-atmosphere system at a temperature of 250-degrees F. It did this by separating the open expansion tank in the attic from the water in the system piping through the use of a double dip tube that allowed the heated water in the system to move the mercury up and down, much like the bladder in a modern compression tank. It was like a chemical relief valve. The hotter water made for a more efficient gravity system since we didn’t yet have circulators.

There were two heating industries back in those days. The steam people came first, with James Watt's invention of the radiator. The challenge then was that there was no such thing as ASME, or ASHRAE, or I=B=R. Heck, they didn't even have relief valves you could take seriously. This was a time of tinkering inventors, and every 36 hours, somewhere in America, a building with a steam boiler exploded. And we worry about terrorists?

Steam explosions, of course, opened the door for the hot water people, and gravity hot water heating arrived as a gift from the Canadians. Mark Honeywell took the gravity system and made it better. The steam people had to respond so they came up with the concept of vapor heating, which is a system that runs on eight-ounces of pressure or less. They also gave us the vapor/vacuum system, which would run between eight-ounces of pressure and a deep vacuum, giving the steam people a way to compete with lower-temperature hot water, while offering relative safety. Before the Vapor Era, the steam folks thought it was perfectly normal to have 60-psi pressure inside a questionably manufactured radiator. How would you like to sleep next to one of those?

Time passed and America waltzed into the prosperous days prior to World War I. They now had several choices – heat with steam; heat with hot water; or heat with a stove or a fireplace.

"Choose us!" the hot water people shouted. "Our systems are quiet and constant and you can control the heat in each room by throttling the radiator valve." As part of their system, Honeywell introduced their Unique valve, which hooked to the radiator with a single pipe, giving the hot water people another way to compete with one-pipe steam. The Unique valve is similar to the modern single-point-connection TRVs that we now see on European radiators.

"The heck with them!" the steam people would shout back. "Choose us. Our vapor systems are all two-pipe. You can throttle the radiator valve to control the level of heat in each room. Our return pipes are much smaller than the hot water guy's return pipes. That leaves you more room in your basement. Our systems can’t freeze like their systems can, and if you choose a vacuum system, we can give you steam vapor that will waft from the boiler at temperatures as low as 150-degrees Fahrenheit. Choose us!"

In the skyscrapers that were rising in Chicago and then New York and other big cities, steam was the logical choice, of course. Water in a gravity hot water system would only rise about three stories, and a water system also presents the challenge of static pressure. The higher the column of water the greater the pressure at the bottom of the system. There are never any concerns about static weight with steam. It moves at 60 miles per hour within a properly sized and designed heating system, and you can balance the flow of the steam by controlling the pipe size, and the release of the air from the vents.

Today, steam remains the medium of choice for moving massive amounts of energy through relatively small pipes. Look under the streets of New York, Philadelphia, St. Louis, Denver, and other old cities and you'll see what I mean. Go into a Manhattan high rise and you'll find tall steam risers feeding either shell-and-tube, or plate-and-frame heat exchangers, and from these flow hot water to warm the air that passes over coils in ventilations ducts. In modern buildings, the battle between steam and hot water has ended in an all-embracing draw, and that's very good, but the question of what to do with older buildings remains.

My daughter, Kelly, went to the University of Notre Dame, and so did her roommate, Kathy. Kathy graduated as a mechanical engineer, and in the four years she attended that storied university, never once did any of her professors take her on a tour of the Notre Dame steam plant that you see in the photo above. The Fighting Irish have everything when it comes to steam- and hot-water heating. It's all there, high-pressure and low-pressure, and yet it's not something that the faculty thinks worth sharing with the students. Graduating engineers have little hands-on experience when it comes to hydronics or steam heating nowadays. What they'll learn they'll probably learn from manufacturers reps, and let's hope that these reps are up to the challenge.

It's the same with people in the trade. Unless you're fortunate enough to have access to an old-timer when you're growing up in the business (and smart enough to ask questions), or unless you're willing to read the books and put in the time on your own, you're probably going to condemn those older systems found in so many American buildings. And that's a shame because, with a bit of tweaking, you can usually make an old steam- or hot-water system hum. You can do what others say can't be done, and that's what building owners want to hear. When a contractor who doesn't have the knowledge looks at an old system and tells the owner that he has to abandon all hope, that owner is going to look for help from someone else.

And the smarter person will win.

To me, a true heating professional is someone who can design and troubleshoot any heating system, regardless of its age. This is easier than ever nowadays because the information is right there at your fingertip. All you have to do is come to and and ask.

Steam vs. Hot Water? Hydronics vs. Warm Air? These are battles of the past. The battle worth fighting nowadays is the one between those who have the knowledge, and those who haven't yet taken the time to get it.

And may the smarter person win.



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