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:

What Happened to Steam Heating?

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.

They All Died

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.

Coal Died Too

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

1970s Oil Crisis

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.

Asbestos Litigation

When your boiler is cast, and again when it is installed using threaded pipe, oils are introduced inside the boiler. Being lighter than water, these oils will eventually rise to the surface and float on top of the boiler water. Once the water begins to boil, these oils become big trouble. As the water begins to boil it forms bubbles, but the oils prevent the bubbles from bursting and result in what is referred to as foaming. Foaming is death to a steam heating system. It causes water to be thrown up with the steam into the system, killing efficiency, and it also doesn’t smell very nice when it exits your radiator vents! So we need to get those oils out of the boiler after installation. The boiler manufacturer installs a skim tapping for this purpose, on which the installer is supposed to install a skim port, which allows the oils to be skimmed away. You’d be amazed how many guys never complete this critical step. Naturally we do, and because you’ll be helping in the skimming process, we install a very user-friendly skim port (complete with an extra port for boiler additives should you be so inclined). That’s just the way we roll.


Skim Port

Our only other major worry is boiler corrosion. A topic a little bit too complicated for our purposes here, but let’s just say that for corrosion to occur, oxygen must be present. And because a steam system is open to the atmosphere, a little corrosion is always going to happen, and that’s normal and okay. But a lot of corrosion isn’t. For a lot of corrosion to occur we need a lot of oxygen. And that oxygen, if present in excessive quantities, is in the fresh water that is being regularly added to the boiler to replace the water lost to escaping steam or piping leaks. Got that? Fresh water is bad for your steam boiler. The old water that has already steamed is fine, as the boiling removed the oxygen. But the fresh stuff is bad news. So we need to keep track of it. And for that reason we offer a Hydrolevel VXT automatic water feeder with every job. I bet you thought we offered it so you wouldn’t have to manually add water to the boiler, didn’t you? Sorry, no, -an ancillary benefit perhaps. The reason is that the VXT has a nifty digital read-out that counts the gallons of water it has fed to your boiler. And by reading the control, we will always know if we have a problem or not. Better safe than sorry, right?


Are you sensing a theme here? Gunk. Steam systems don’t have many maintenance problems, which is what is so nice about them. But we must be ever vigilant about gunk. The other place gunk shows up and causes problems is in the little 1/4″ pipe connecting the Pressuretrol. Remember that the pressuretrol is a safety device, and if it senses that the pressure is too high, it dutifully shuts down the boiler. If gunk gets in that little pipe, as it is want to do, it will fool the Pressuretrol into thinking the pressure is too high and shut down the boiler. Usually in the middle of February when it’s -20º outside. Now in theory you might think it pretty simple to just unscrew the pressuretrol and stick a pipe cleaner in there and get back to heating again. Except that you can’t. Before you can unscrew the Pressuretrol you have to unwire everything first. Things just went from simple to complicated. To avoid this, we offer custom “trees”on all our Pressuretrols and Vaporstats installations as an option. No unwiring required to clean out the piping. We also increase the pipe diameter so a clog is less likely in the first place. See? We are always thinking about you.

Pressuretrol Trees

Not only do we have to flush out those wet returns, but we also need to flush out the boiler annually. It’ll have just as much gunk in it, and it’s no good leaving it there. But this typically isn’t done either because, once again, there’s no way to do it. Just filling and draining the boiler with the normal water fill hasn’t the pressure needed to entice the gunk to leave. And that’s why we install King Valves on all of the steam supplies and returns. Now, come maintenance time, we can close all the valves, fire the boiler, and build up some real pressure. Then we hook up a hose to a drain, open the drain, and viola! -that gunk is moving like you-know-what through a goose. Of course, if you wait 10 years to have us out to do the maintenance, this might not work so well. But if you call us every year, it works like a charm. So call already. That’s why we put the valves there!


King Valves

If you’ve ever had to blow down your steam boiler (and I am sure you have), you know how nasty that boiler water can get. That’s what happens to water in an iron system that is open to the atmosphere. So just imagine all of the gunk that accumulates over the years in all of your returns that are below the waterline. Eventually, they will fill up with sediment and prevent the condensate from returning to the boiler and now we have a big problem. The simple solution is to flush out those wet returns annually and all will be well. Except that in most cases you can’t. Because boiler drains were never installed on the elbows to allow the flushing to take place. Rest assured, we install drains at every 90 degree elbow we install below the waterline. That’s premium workmanship

Wet Return Drains