Besides the fireplaces, Comstock House has a radiator in every room except for the kitchen and servant's bath. (The servant's bedroom also has the tiniest one, so any cynical observations about the Oates' disregard for employee welfare may well apply.) The system works, but takes hours to raise the ambient temperature into the comfort zone after it has gone cold. Left on constantly during winter and regulated by the thermostat, it keeps the house quite comfy if some rooms are also blocked off - see the posting on zone heating for more on that.
The radiators are heated with circulating water, not steam. Called "hydronic heating" today and popular in radiant systems for baseboards and floors, it was simply "hot-water heating" at the turn of the century, and a better alternative to steam in private homes. Although it takes longer to warm the cast-iron Victorian/Edwardian radiators with hot water, residents are spared the infamous knocking and banging in the pipes, not to mention the safety risks of pressurized steam.
A third option existed in 1905: Just invented a few years before was the "gas-steam" radiator, which was fundamentally an uninsulated water heater. Here a gas pipe feeds a small burner built into the radiator itself. It had the advantage of being the most efficent system because the radiator itself was the boiler; no need for hot water or steam to travel all the way from the basement. The drawbacks were that it had to be manually filled with water, and there was always risk of the flame blowing out, being so close to a drafty floor. Still, they were a popular choice for the day; in the 1904 Press Democrat, the Santa Rosa Lighting Company ran ads encouraging the public to "Ask to see the latest in gas heating, 'A GasSteam Radiator.'"
The hydronic system (technically: a two-pipe direct return water loop) in Comstock House has four basic components: The boiler in the basement to heat the water (Comstock House had a not-so-venerable WWII vintage "Petroheat" converted from oil to natural gas in 1956); An electric circulator pump to push the hot water upwards three stories; The cast-iron radiators; and an expansion tank in the attic intended to hold the water overflow when the system's at full throttle (although we've never seen much more than a liter in the tank).
For details on the system, the Brainerd Jones contract disappoints. On page 23 of the contract specs the architect writes only, "The heater, boiler, pipes, etc. will be provided for under separate contract." Sadly, that document is lost.
Although no trademark or patent numbers can be found on these radiators, they are almost certainly the "Rococo" model two-column (shown above) made by the American Radiator Co. By 1904, the company had a well-deserved reputation for making the finest radiators and residential boilers in the world. At the St. Louis World's Fair that year, they won a prize for their exhibit of a full-sized model house with a cutaway front, allowing fairgoers to admire the boiler and radiator heating system. (After the fair, the house was sold and moved to Webster Grove, Missouri, where it still stands.) American Radiator also published a booklet in 1904 encouraging customers to paint their radiators in multiple bright colors -- quite the difference from the habit today, of trying to hide the radiator by painting it to match the wall behind, or a neutral shade.
But what of the original boiler? All that we know for certain is that there was a coal bin in the basement "Heater Room" on the blueprints, so we can assume that it was coal-fired. It's also likely that it was one of American Radiator's matching "Ideal" model cast-iron boilers, such as the example below. This was also the the type on display in the World's Fair cutaway house. An illustration showing how the boiler worked can be found on pg. 199 of Baldwin's reference book (see notes).
Presumably the miserable servant, chattering after a winter's night with a peewee radiator in the chilly northwest bedroom, warmed up before dawn by shaking down cinders with the lever at left and shoveling fresh coal into the boiler's maw. Wasn't the Gilded Age grand?
NOTES: Should you ever need to repair an old radiator or hope to understand an antique heating system such as ours, see the classic reference of the era, "Hot Water Heating and Fitting" by William James Baldwin. Google Books has the 1908 edition as well as several earlier versions. The HeatingHelp.com library also is a great resource for old manuals and other source material.
