What Happened to Steam Heat?

What Happened to Steam Heating?

Steam heat has gotten an undeservedly bad reputation over the years due to high heating costs, unbalanced heat, and strange (and sometimes quite loud) noises. As we shall see, these are all symptoms of neglect rather than actual properties of steam heat. Steam has been around for a long time, and the very fact that all those steam systems are still going today (despite that neglect) is a real testimony to steam heat’s resilience. There’s no heating system yet devised as robust, long lasting, and free of maintenance issues as steam. It is simplicity itself. So what happened? Read on dear reader, for the afflictions poor steam heat has had to battle:

They All Died

That’s right, they all did.

The last steam systems were installed before World War II, and the men who installed them, serviced them, designed them, and understood them died a long time ago. Because steam systems are essentially bulletproof, there’s still hundreds of thousands of steam systems around. But owing to the fact that it is no longer installed, future tradesmen lost all interest in learning and understanding it: Steam is dead. Long live the future! Not surprising then that the systems became neglected and -much worse- inappropriately altered. Steam is pretty simple, but it has ironclad rules for how it must be piped and operated. And when those rules are violated (and who is left to know what they are?) steam rebels.

Coal Died Too

All steam systems were originally coal-fired, and thus the systems were designed for a constant fire. But in the 1950s, oil burners came in to use. Oil burners let the Missus of the house finally drop the coal shovel and, one by one, coal-fired boilers were converted to oil. She was thrilled. But the steam system wasn’t. You see, an oil burner works much differently than a coal fire. The coal fire was constant. The oil burner (and later gas) cycles on and off. Usually once an hour during the winter. This change required a complete transition in the way the system vented itself. But for the most part that change never occurred. Why? See #1 above. They were all dead, remember? Who was around to know or care?

Those old steam guys were pretty clever. You see, they knew that when water became steam it expanded in volume 1700 times, and when it condensed, a vacuum was formed. They also knew that water at atmospheric pressure boils at 212º. But with negative pressure (a vacuum) water can be made to boil with a temperature as low as 180º and still make steam. Very efficient. And very clever, as I said. So the systems were designed to operate in a vacuum.

But what happens when we replace coal with an oil or gas burner? The burner shuts off every hour remember? So what happens to the vacuum when the burner shuts off? Well, when the burner shuts off the vents open and that loses the vacuum. Simply put, steam systems can no longer operate in a vacuum with modern burners. That’s long gone (unless one wants to go to considerable expense installing a vacuum pump).

To compensate, this conversion necessitated a drastic change in the way steam systems vented. Which of course largely never happened…

Picture your steam system when the boiler is not running. All those miles of piping and all those great big radiators are filled with air aren’t they? When the boiler fires, all that air needs to get out so that the steam can get in and begin to heat the home, right? They can’t coexist. The quicker this happens the more efficient the system. They didn’t need or use big vents in the coal days: who cared if it took an hour to get the air out? The fire was lit in the fall and generally stayed lit until spring. Sure, the initial venting took a long time, but because the fire remained lit, the vents remained closed, and the air stayed out until spring. Six months of air-free vacuum with one venting cycle.

But today our burner comes on and shuts off every hour. Which means every hour of every winter the burner fires and consumes fuel chasing the air out so the steam can get in. The bigger the main vents, the faster the air can get out. The faster the air gets out, the more balanced and efficient the system runs.

Except you don’t have large main vents. You still have the same size vents they used in the vacuum era. In a way it’s like saying your steam pipes are clogged (with air), and the clog is preventing the steam from getting to each of the radiators quickly and at the same time. Those tiny little coal-era vents on your returns in the basement are woefully inadequate for a modern system. And they are costing you a lot of money and comfort. Comfort because with slow venting, the radiators closest to the boiler are going to get hot first, long before the ones furthest away will.

1970s Oil Crisis

Steam boilers were in for a big change when the price of energy skyrocketed in the 1970s and efficiency standards were mandated. When steam is used as a form of energy it’s best to think of it as a gas (which it is). It is invisible and contains no more than 2% water, best if less than 1%. It’s nothing like the wet steam that rises off your stock pot when making pasta or from your tea kettle. That steam is wet, and no good for energy production. Before the 1970’s steam boilers used an internal steam chest to separate the water from the steam. Those old boilers were quite large as a result. When the efficiency mandates appeared, boilers had to get a lot more efficient, and to do that, they had to get smaller. For steam boilers that meant the steam chest had to go. But then how to get the water out of the steam if we remove the steam chest? Once again, clever men went to work and a solution was devised. It was found that by carefully designing the near-boiler piping coming out of the boiler, that this piping arrangement could do the same job as the old steam chest in separating the moisture from the steam. It was a great victory for the boiler manufactures. Not only could they make boilers that met the efficiency mandates, but they could also off-load the cost of the steam/water separation process to the contractor or plumber who was to install the boiler!

You can guess what the tradesmen thought of this arrangement. Not much. So lesser boiler manufacturers began to skimp on their piping requirements for their boilers and this naturally brought them more business from contractors. The homeowner suffered because of the loss of efficiency inherent in wet steam, but for the most part they were in the dark so complaints were few and far between. As usual, people just blamed it on the steam itself…

Today, sad to say, far too many steam boilers are installed with incorrect near-boiler piping. This results in the boiler producing wet steam, which is very inefficient and is often the main culprit in high energy bills. It can also lead to banging and other disconcerting problems

Asbestos Litigation

Lastly, steam pipes must be insulated for systems to operate efficiently. The great asbestos scare of the 1980s caused many of them to have their asbestos pipe insulation removed and then never reinsulated. This is a disaster for steam systems. It costs money to generate your steam, and cold uninsulated pipes knock it down to condensate before it can do much work heating your home. Without insulation more steam must be produced, which means more fuel must be consumed. If that weren’t bad enough, the resulting extra moisture in the pipes from all that steam condensing leads to banging, spitting vents, and other system maladies. Especially today, the insulating of all steam piping should be considered mandatory. And, unlike fuel, you only have to buy it once.


There are some additional, smaller, details that improve system efficiency such as proper pressure regulation, make-up water characteristics, and so forth. When all of these items are addressed together in a holistic approach there is never a reason to contemplate replacement of a steam system. Efficiency will easily rival a standard hot-water/baseboard system, and at a fraction of the cost of total replacement.

Remember: It’s not steam’s fault if yours is acting up, no matter how many folks tell you that it is. In fact, your system should probably earn a medal for continuing to carry on, decade after decade, with nothing to sustain it but neglect!

So now you know: Count yourself one of the lucky ones if you have a steam system.

If yours is acting up, rather than tolerating a poorly performing system or paying an arm and leg for a replacement system, contact us and we’ll make things right for you. Then you, too, can enjoy the efficient, comfortable, and quiet heat that is steam.

Should you happen not to have a steam heating system, now you understand that there’s never been a heating system that is as robust, long-lasting, and free of maintenance as steam.

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