The Lost Art Of Steam Heating

We got pointed by [packrat] to a 2015 presentation by [Dan Holohan] on the history and art of steam heating systems. At the advent of central heating systems for entire buildings, steam was used instead of water or air for the transport medium. These systems were installed in landmark buildings including the Empire State Building, which still use them to this day.

A major advantage of steam-based heating system is that no pump is required: the steam will naturally rise up through the piping, condenses and returns to the origin. This can be implemented as a single pipe where condensation returns through the same pipe as the steam, or a two-pipe system where the condensate returns through its own pipe.

In the presentation, Dan walks us through his experiences working on many of these steam heating systems in major US buildings, the types of systems, fixes implemented by engineers long since dead and the particularities of maintaining these systems.


51 thoughts on “The Lost Art Of Steam Heating

  1. The only thing boiler rooms were good for was creating explosions making it easier for rogue nations, namely the United States, to make assassinations look like an accident. This is why I only use firewood to heat my home, because while the government can take away my freedom, they can’t take away my wood.

    1. You should definitely look into ‘rocket mass heaters’, then. They burn a tenth the wood, don’t smoke after the first five minutes or so, and can’t cause a chimney fire because soot can’t form. Most folks only need to run theirs for an hour or two a day.

        1. The nice thing about “efficiency” is that you can measure it any old way you like, or between whatever points in your system you choose to give you a nice answer :)

          A normal wood burning stove will claim 75-80% efficiency but that seems to be in terms of converting the wood into heat, not in terms of getting that heat into your building. Most of it goes up the chimney as hot flue gas, which *must* be hot in order to prevent creosote formation.

          With a rocket mass heater, you get a hot/complete burn and then extract most of the heat from the flue gas and store it. That doesn’t cause creosote because the heat is extracted from the completely-burnt gases, not from the combustion chamber. You can even extract so much heat as to condense the water vapour in the exhaust (a significant extra!), though the condensate, being basically instant acid-rain, tends to be quite corrosive and you need to make sure it can’t drip back to the firebox or onto metallic components.

        2. It really depends on how you define ‘efficient’. If you simply mean ‘burn wood’, then RMH’s aren’t much more efficient, true enough. If, on the other hand, you mean ‘warm people up’, then RMH’s *are* up to ten times as efficient, as they have been proven in practice to use up to ten times less wood to do the job. Part of the problem is that regular wood stoves *MUST* maintain sufficient heat in the chimney to eliminate the formation of creosote from unburned volatile gases, which means they are dumping at *LEAST* 250F (…and usually more like 400-800F) into the air the entire time that they are burning just to keep a chimney fire from starting. RMH’s don’t create creosote because of how they function, so the exhaust is generally kept to around 220F just to keep water from condensing. Apparently some folks use a condenser so they can pull all but 60F from the exhaust air. (I watched a rocket water heater being dismantled to check it out, and–after being in daily operation to 2+ years, there was only about a half-inch of dry soot in the chamber. Back in the day, my family’s wood stove could gather that in our chimney in a few months!)

  2. “A major advantage of steam-based heating system is that no pump is required”, technically the same is also true for a gravity fed water system. But it does mean that every rad, the further away you go from the boiler, needs to be placed higher.

    1. It’s also untrue in many steam systems. My company does designs for civil infrastructure, and I can’t tell you how many steam booster PUMPS we’ve slated for demo. Not to mention the pumps that go into the condenser pits, coolant wells, etc… Just because the primary loop of a system doesn’t ‘normally’ require a pump doesn’t mean the system is pump-free.

    1. Nice! I always loved that show .. and it still holds up.

      “Connections”, “Connections 2”, “Secret Life of Machines” amd “The Woodwright’s Shop” were pretty much my favorite PBS shows of all time.

  3. My WW1-era NYC apartment building uses steam heat. One important thing they forgot to mention is that the furnace is the domain of an angry fire demon. Never, ever insult the demon by speaking aloud “is it cold in here?” That bastard will fry you and steam is (surprisingly) a dry heat. My building is 14 stories and, as a mere denizen of the third floor, am desiccated collateral damage in the mission of boosting the steam up to 14. I have a wrench longer than my forearm to make sure the supply valves are dogged down tight and the heat from the supply line is still enough to turn the place into the Sahara.

    The other fun thing about steam heat is that if the radiator isn’t sloped correctly a little bit of water will pool at the bottom. The next time the furnace cycles that water flashes into steam and delivers a hell of a loud water hammer to the pipes.

    1. I’d always heard that the knocking sound in the radiator pipes was caused by bubbles rising up through the fluid and breaking the sound barrier (which was lowered for some reason inside that medium?) This may have been for an oil heating system. Also I don’t know how knowledgeable the people who told me that yarn were. As I type it out, it seems pretty fishy actually.

  4. More impressive to me is THE LOST ART OF STEAM COOLING. Some places use steam to COOL as well. A little food for your update article.

    from coned
    Large buildings use machines called chillers to provide the cooling effect. A chiller removes heat from a liquid (typically water). This chilled water is then used to cool and dehumidify the air. Chillers use two methods to cool the water. These are called the vapor compression and absorption refrigeration cycles. Both methods evaporate a refrigerant at a low pressure and condense the refrigerant at a higher pressure.

    The vapor compression cycle uses a mechanical compressor to create the pressure difference necessary to circulate the refrigerant. This is the same technology used in home window air-conditioning except that a steam turbine replaces the electric motor to drive the turbine. One advantage to using steam is that a building uses less electricity during peak periods.

    In the second method, the absorption cycle, water is evaporated to provide the cooling and is then absorbed by a salt solution. Steam heat can be used to boil off the water in order to start the cycle again. Besides saving electricity, absorption chillers do not use chemicals that can harm the ozone layer, which the vapor compression method frequently does.

  5. taking out the pump adds loads of complexity and compromises for pipe runs and radiator placements. microbore central heating is just so easy and simple. and no risk of water hammering or explosions !

    1. A lot depends on the exact conditions, like a wood burning range cooker with a back boiler in an off grid location, convection fed plumbing makes sense when a pump is not an easy option.

    1. Most Air Force Bases had a central heat plant. You regulated your room temp by opening a window (LOL)

      During the 1980’s, Bitburg Air base and Bitburger worked out a method to use the breweries waste heat to heat the base. They got some sort of environmental award for that.

    2. Virtually all ex-eastern block blocks of flats (which are very…blocky…) use some form of central heating that is not in the building, be it a dedicated heating facily or a power plant that’s nearby or even large trash incinerators.

  6. The art can’t be that lost – I’m sitting in a house with exactly that system, and my heating guy knows it soup to nuts!

    A well maintained system does not humidify the house as the radiator vents only let air out of the radiator and close when the steam reaches them.

    The system has its charms and quirks. It can heat quickly as the radiators can get much hotter than hot water radiators, and the systems were designed during an age of poor insulation and air sealing. The radiators typically have a larger horizontal surface catching dust all summer that cooks off fragrantly during the first firing up of fall. They hiss as the air within them is expelled. The system clunks and creaks (especially early in the heating season) as the pipes expand and contract, rubbing against their supports held by a house that itself is shrinking because of the seasonal moisture changes.

    Among the reasons why hot water loops replaced them are cost of install – steam pipes are large, 2-4″, and need to be carefully installed to maintain that slope. Hot water pipes can be much smaller and don’t require a slope. Another factor is that the steam pressure must be carefully regulated to prevent explosions. Boiler explosions were not uncommon when most of these systems were originally installed, but modern safety code has all but eliminated them. IIRC, the pressure safety switch on my boiler (that kills combustion) is set at something like 0.5 PSI. There is also a low water cutoff, and almost certainly another mechanical pressure valve within the boiler.

    Maintenance-wise, it can be work. The valves can stick close over the summer preventing the radiator from heating. Or occasionally open, allowing vapor to escape. A stuck-open valve, or a leak in a connection somewhere will cause the water level to drop slowly. If that lost water isn’t replaced when necessary then the eventual result is a cold house as the low water level sensor stops combustion. That usually happens during times of most usage, i.e the middle of the night during a prolonged cold spell and its 0 degrees F outside. The pipes and radiators slowly rust on the inside, and that rust drains down to the boiler with the condensate. Periodically that rust needs to be drained out of the boiler. Basically the system requires some annual maintenance to keep running well.

    The hot air furnace in the newer part of the house has been maintenance free for the past 6 years (with the exception of routine air duct filter replacement) and almost completely quiet. I can only hear it if I’m in the attic near to the furnace.

    1. My grandfather had a steam system. I remember the radiators whistling through the air vent (it looked like it was some sort of valve. It also looked like it had return pipes.

      When I was still young, he had the furnace replaced with a new model. It ran off gas, where the older one may of been coal (my uncle at the time still used coal).

      1. Yeah, our burner is oil-based, installed in the ’90s. When it eventually gives up the ghost it will likely be converted to gas, which is economically and environmentally preferable now. I’m guessing that wood, coal and coke were used in early burners, and that the inability to quickly stop combustion contributed to many explosions.

    1. Yup. about 100 to 120 years is all you get….

      Proper water treatment, maintenance, and operating practice protects the boiler (I pulled my well abused sectional when I bought the house because of the inefficient burner and physical damage by prior residents and their….. problems.), and the rest of the system sees little oxygen and distilled water. In the end, the boiler is self-consuming, but not in the same way as high pressure or once through types are.

  7. Ah! My college dorm and workplace. Such warm memories! I was very proud to have had the privilege of exploring the steam tunnels a bit. We had to hold a broomstick out in front of us. That way if there was a pinhole in the steam pipe it would cut the broom in half warning us before we walk past cutting ourselves in half!

  8. There’s a fair amount of confusion in this post and its’ comments between single-pipe steam, the different flavors of dual-pipe steam, and hot water heating.

    But if you read Holohan assiduously, all will be made clear in time ;)

    1. Exactly what I was thinking. One pipe two pipe hydronic ect people think it’s all the same NOPE! ONE PIPE TWO PIPE BLACK PIPE FLUE PIPE. I am a poet and didn’t Even know it lol

  9. In the first part of this decade I was stationed at a very large Marine Corps base on the eastern seaboard. I noticed pretty quickly that the entire base still uses steam heating. Looks kind of cool to see the massive piping stretching all around the base, it really fits the industrial look of ww2 buildings anyways. I would try to ask questions whenever I saw the maintenance guys working on them, and it seems that they have to pretty creative in order to keep the systems running properly.

    1. Not anymore. If that’s the base I’m thinking of, then my company just completed a huge design project to remove the entire steam system from the whole mainside, airststion, and a few other areas. Steam has officially gone the way of the dinosaur, at least on that particular installation.

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