The Lost Art of Steam Heating, by Dan Holohan.NOW YOU'VE REALLY DONE IT! Of course, you didn't do it alone: you had lots of help from your support network. "Get rid of that bachelor-pad in the high-rise!", they said. "You're married now, got a kid, you need a real house, in a real neighborhood. "Get an older home," said your Dad," The new ones are all built with cardboard and glue!". "Get a big house," said your Mom, "You can always close off some rooms until you need them." "Established neighborhoods are have less traffic, more trees and that wonderful feeling of permanence!" said your friend Sam, who has such a vibrant sense of style. So you spent a season of weekends house hunting and finally found it: That stately, ivy-adorned Tudor on a street of lovingly protected elms. "Charming! A real classic," cooed the real estate agent. "Built like a rock!" declared Dad, "but replace that old steam boiler!" "Four bedrooms,plus a sitting room and an office and a breakfast nook and a sunroom and..." rhapsodized Mom. "You can do the fireplace in faux marble, blow out this wall to make an up-to-date kitchen looking out on a deck with a gazebo and a hot tub..." vibrated Sam. The possibilities seemed endless. A little time, a little elbow grease...
That was then, and this is now. Today, you find yourself listening to a steam heating system that defies your understanding, and looking at a bank balance that's an all too easy to understand. You have learned that the whole arcane rite of real estate closing has but a single purpose: relieving you of all that cash that was to be used for faux marble, a new heating system and "blowing out walls". Two questions are competing for your immediate attention: "How serious ARE those banging noises I'm hearing?" and "Where's that support network now?"
This is the first in a series of articles dedicated to helping you peacefully coexist with an old house. In writing the articles, your author has made some assumptions:
The boiler itself is fairly simple in principle. If you took one of those big iron radiators, surrounded it with insulation and sheet metal, and built a fire under it, you'd have a boiler. The burner and all its various controls are similar to those in forced-air systems, subject to the same failures and amenable to the same fixes. In other words, if oil is the preferred heat source in your area, the burner in your boiler will be very much like the burner in your neighbor's oil forced-air system.
When the thermostat "calls for heat", the flame comes on and begins to heat the boiler. In an old system, there may be a ton or more of iron that needs to be heated before any steam develops. Then, there may be several tons of pipe and radiators to warm up before the heat gets to you. Don't expect to feel toasty five minutes after turning up the heat. For the same reason, the house will go on warming up for a while after the thermostat tells the boiler to quit, just from leftover heat in all that metal. If you are a chronic thermostat jiggler, this delayed-action response will drive you to distraction. It's best to pick a setting and stay with it.
Once some of the water turns to steam, it tries to move up through the pipes to the radiators. The pipes are already full, though, of cold air. The steam can't get through very well until the air is out of the way. The little cylindrical air vents on the side of each radiator let the cold air out. Once the hot steam fills the radiator and hits the air vent, the vent should close automatically.
As the steam hits the cooler inside surface of the radiator, it gives up its heat and turns back to water. In doing so, it shrinks drastically, and this creates a vacuum in the radiator that pulls up more steam from the boiler. No pressure necessary. The water flows back down to the boiler in the same pipes that brought the steam up, because these pipes are all sloped slightly back toward the boiler. When the whole business is cooking along, you have steam going up and water coming down the same pipe at the same time. Neat, eh? Eventually the house warms up, the 'stat turns off the flame, and everything slowly cools down. Even the air vents, which re-open as they cool. Ahh!
So simple in principle. What could possibly go wrong? Well...
If the pipes are not sloped properly, they get puddles of cold water in them and the steam can't get through. This can happen because floors sag over the years, and the house settles, disturbing the original slope. The steam will try to get through, and produce loud hammering noises as it does so. Along with cold rooms, you get banging, thumping and clunking to go with your normal ticking, hissing and wheezing. A good (read "old") boiler man can usually figure out which pipes are sagged, and correct them by adjusting pipe hangers or adding supports.
Radiators are supposed to lean gently toward the inlet pipe, so that the condensed water will flow out. Sagging and softening of floors can eliminate or reverse this lean, causing performance problems in the radiator. Carefully jacking up a radiator and placing shims under one end will restore the proper tilt toward the inlet end. This can overstress pipes and fittings, and therefore is not a job for the faint-hearted. Leave it for that old boiler man.
If one of the air vents sticks closed, that radiator will stay cold. If one sticks open, steam hisses out and hot water drips on the carpet. Replacing some of these vents from time to time is part of normal maintenance on a steam system. If you know what a screw extractor (aka Easy-Out) is, then you pass the test of handyman skill needed to replace air vents. Plan on spending $8 to $25 each, depending on style and source. When you break off the stub of the vent in the radiator, you'll need that Easy-Out!
There is a hand-operated valve on the inlet of each radiator. In most systems, you should not use this to adjust the heat. Remember, there is a 2-way simultaneous flow past that valve, and if you restrict the top half of it, you will cause trouble. The valve should be all the way open or all the way closed.
Radiators are ugly by nature. If you keep adding layers of paint, they will become inefficient as well. The less paint, the better. Try to convince yourself that ugly is classic!
There is always some loss of water through the air vents. To make up for this loss, somebody has to add water to the boiler, usually once a week. This is done by opening the feed valve, which connects the domestic water system to the boiler. This valve is of course clearly labeled and easy to reach. Riight! (Hopefully, your home inspector pointed out this valve when you had your pre-purchase inspection.) Caution! If you can't see any water in the sight glass, there is a chance that the boiler is dry. Adding water to a hot, dry boiler can cause an explosion! There are several safety systems in place to keep this from happening, but just in case, turn down the thermostat and let the boiler cool for a while if you find it dry.
The level should be kept within an inch or so of the center of the sight glass. Some boilers have automatic feeders to do this for you, but they shouldn't be trusted completely. Check that sight glass once a week anyway! Sight glasses do get dirty, and need to be replaced every 2-3 years.
By now, somebody has told you about draining the low-water cut-off every week. Yes, you really have to do that! This device, mounted on the side of the boiler, has a float in it that detects the water level and will shut off the flame if there isn't enough water in the boiler. It can save you from a major disaster. But, for some reason known only to steam engineers and other Druids, sediment (technical term: crud) builds up in it and can keep the float from sinking when it should. Therefore,you have to open that valve on the bottom of the LWC and drain out the crud every Sunday morning. If you do this regularly, the drain valve will always be easy to open, easy to close, and your boiler will never crack. Ignore this ritual at your peril! When you have run out enough water that the crud has cleared from the stream, close the valve and check the water level in the sight glass. It will probably be low, so this is a good time to top it off. If you have an auto-feed valve, you should have heard it open in response to the water loss when you drained the LWC. If it didn't open, and the sight glass water level is below the arrow embossed on the side of the LWC, call that boiler guy to fix the feeder. Most autofeeds have a bypass so you can still add water manually. Use that till help arrives.
There are several other gadgets on the boiler that only need attention at the annual professional maintenance check. Most important is the pressure-relief valve, which would open up if the pressure in the system began to build up. It should definitely be tested annually. The metal stack between the boiler and the chimney is another often-overlooked item. If it gets soft or rusty, it needs replacement. The yearly exam should also include testing the thermocouple relay, checking the pilot and main fuel-air mix adjustments, and testing the pressure cut-out switch. No, I'm not going to explain those,(see the book reference at the end of this article if you are curious) but make sure that they are included in the annual check-up.
Sooner or later, someone is going to tell you it's time to replace the boiler. Here are some bad and good reasons to spend several thousand dollars.
If you are facing replacement, the asbestos becomes an important consideration. Many reputable heating contractors will not remove the old unit until the asbestos has been removed. You must get a qualified asbestos abatement contractor to do this work, and its not going to be cheap. A do-it-yourself removal job, or one done by unqualified people can produce a serious contamination all over your house which will be far more expensive to clean up, and dangerous to live with. The EPA publishes a booklet called "Asbestos in the Home." It's a `must read' if you have an old house.
One more word about pipe and boiler insulation: Before worrying too much about asbestos, have the insulation sampled and tested by a laboratory. If your house was built before 1930, you may find that it's nothing more dangerous than a mixture of plaster and horsehair! Not likely, but possible.
I suggest you take this next section and copy it into your word processor. Print it in a big font on some very durable paper, and hang it near the boiler.
So, does that monster in your basement look a bit less fearsome now? Low-tech can be more interesting than intimidating, and the more you learn, the more comfortable you will be with your old house.
If you find yourself intrigued by the mystery of it all, and developing admiration for those pre-Edison engineers, you will enjoy this book:
The Lost Art of Steam Heating, by Dan Holohan.
Holohan is a real boiler expert, and a very competent writer! His book is very readable, much deeper than anything here, and could save you K$'s! If you are a mechanically curious person, (and having gotten this far, I'm willing to bet you are!) you will find this a fun read even if your boiler is still working perfectly!