Steam dreams

Feature Story

Used properly, steam heating can still be a valid way to provide indoor comfort

By Frank ‘Steamhead” Wilsey

So, you get a call where someone wants you to fix a steam-heating system. What comes to mind?

Why doesn’t this stuff just go away, like they said it would back in the 1950s and 1960s?
Why, indeed? Let’s take a look.

Low-pressure steam heating, the kind you find in older homes, has been with us since the 1850s. During the ensuing 90 years, an amazing variety of steam systems came onto the market. Heating contractors continued to install residential steam systems right up until World War II.

After the war, the demand for ultra-cheap housing led most builders to have their heating contractors install scorched-air systems, despite the decreased comfort and efficiency levels these systems provided. In those days, fuel was cheap enough that comfort wasn’t an issue, you just turned the thermostat way up if you were cold. Steam continued to be used in commercial applications.

As we’ve all seen, many, many steam systems, from 1854 originals to those built in the early 1940s, are still running today. Recently, we have seen a renewed interest in residential steam heating, with some brand-new installations being made. This technology is still valid and has some inherent advantages.

So how come we have so many problems with steam systems?

The biggest mistake I see in the field will certainly wound the oilman’s heart. When these systems were converted from coal firing to automatic firing, they were not updated to work properly with the vastly different characteristics of automatic firing.

Those of you who have used a wood stove know that once the stove is lit, the fire burns all the time. You can raise and lower the burn rate with the dampers, but you can’t shut it off. This is how coal boilers worked. On steam, this meant that once the air was out of the system, it stayed out until the fire died down. If the venting process took an hour, Junior’s bedroom stayed cold longer, but when it finally got warm it stayed warm.

Once you installed an oil (or gas) burner, everything changed. Listen to one of my favorite old-timers, Frank Graham, writing in 1946 in Audel’s Oil Burner Guide: ‘If certain parts or rooms of the building were difficult to heat when using coal for fuel, what is the usual result in converting to oil? The same difficulty will most likely be present, or conditions rendered worse on steam systems. The type of venting which will work satisfactory (sic) on a coal-burning system will not be satisfactory on a conversion job.”

In other words, if you don’t get the air out quickly, the steam won’t fill the system quickly or evenly. Do you see now why Mrs. Jones keeps complaining that her bedroom is cold? It’s the last radiator on the main. Look at the end of the main and you will likely find one of three things, assuming it’s a one-pipe or two-pipe air-vent system:

There is no vent at the end of the main.
There is a vent, but it’s not working.
There is a vent, but it’s too small.

You need enough venting capacity to allow the main to fill with steam in one to two minutes, measured from the point at which the boiler starts ding steam out to the system. This way, little or no steam starts moving into the radiator runouts until the main is full. At that time, steam is available at every runout and every radiator gets steam at about the same time. And the burner doesn’t have to run nearly as long to get steam to that last radiator.

To size main vents, we first have to know how much air is in the main. We then choose a vent that will vent that amount of air in a minute at two ounces of pressure. That’s right, two ounces, not two pounds; that’s all you need to fill that main with steam. Sometimes this requires more than one vent on a main, as shown in the photo.

Fortunately, steam-heat enthusiasts Gerry Gill and Steve Pajek have just made this job a lot easier. They set up some laboratory equipment and measured the capacities of commonly available vents, as well as some real old ones. They then published the results in an e-book that is available on Dan Holohan’s All proceeds from this e-book will go to charity.

Some recommended reading:

The Lost Art of Steam Heating and Dead Men’s Steam School, both by Dan Holohan, and Patrick Linhardt’s Field Guide to Steam Heating, available on
Audel’s Oil Burner Guide by Frank Graham (any edition from 1946 through the 1950s). Check out used-book Web sites such as

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