why do my radiators make so much noise

Steam radiators have been used to heat homes for more than 150 years. Although you won't find them in homes built after about 1940 or so, many of today's older homes still have their original steam heating system. The advantage of steam is that it flows through the pipes under its own pressure, so there's no need to install a mechanical pump. Over time, though, steam radiators can start making annoying sounds such as loud banging or high-pitched whistling and squeaking. Fortunately, you can silence most common noises without calling a plumber. Quiet the Clanging If you hear a banging or knocking sound, then there's probably condensed steam (water) trapped in the pipes. As steam rushes through the system, it pushes the water forward at high speed. When the water hits up against a valve, elbow, or other plumbing fitting, you hear it.

Most of the time you can solve this problem by simply shimming up one end of the radiator so that it tips back toward the boiler. That way water won't be able to settle inside the system. Silence the Squeaks If a radiator is squeaking and whistling, you'll need to replace its air vent, which is attached to the pipe at the bottom of the radiator. You can buy a replacement air vent for about $10 to $15 at most plumbing suppliers. While there, also pick up a roll of Teflon tape and some graphite packing. Both are used to create airtight threaded connections. Begin by turning the thermostat all the way down to shut off the heating system. Next, hold the new air vent upside down with its threaded stem facing up. Wrap Teflon tape around the threaded stem in a clockwise direction that way, when you thread in the vent, the tape won't unravel.

Cover the old air vent with a thick cloth (which will protect your hand from any steam or hot water), and twist it off by hand. Turn the vent to the left counterclockwise and be careful not to apply side pressure, or the vent might snap off. Once the old vent is out, take the new air vent and thread it into the radiator. Be very careful not to cross the threads. Hand-tighten the vent until it's vertical. Don't use pliers too much pressure could crack the vent. The new vent will allow trapped air to escape, reducing the chances of whistling or squeaking. Next, use a screwdriver to unscrew the handle from the top of the radiator valve. Then use an open-end wrench to loosen the packing nut that holds the valve stem to the valve itself. Spin off the packing nut by hand.

Now wrap graphite packing around the threaded portion of the valve stem. As with the air vent, wind the packing around the stem in a clockwise direction. Hand-thread the packing nut back onto the valve and then tighten it with the wrench. Screw the valve handle back onto the valve. When you're done, turn up the thermostat, and wait for the steam heat to kick on. Check your work for leaks, and enjoy the silence.
and have it. In a working steam installation, steam leaves the boiler, condenses in the radiator, and trickles back down to the boiler at the bottom of the pipes (pretty neat trick for ancient technology, by the way). In order for the water to clear the pipes they all need to be angled back to the boiler, as does the radiator itself. There are actually specs for this which you could get from your local plumber's union (and probably City Hall, too) if you really wanted to.

If liquid water is in the pipes when hot steam comes up from the boiler, the steam insta-boils the water (usually not much of it), and the rapid boiling causes the loud pops you hear echoing through the system. For diagnosis: pipes expanding from the heat sounds like gentle haunted house creaking; stuck condensate sounds like Beezelbub banging pots and pans together all over your house staggered with rifle fire. So the solution is to make sure everything's tilted correctly. The radiator needs to be higher on the side opposite the feed pipe than at the feed pipe, and all the horizontal (eg, not vertical) feed pipes should be at an angle also. You have to be careful not to over-do it, of course, since black iron can crack (especially at T L joints), but you ought to be returning it to its original very-slight grade.

Usually the problem starts because the original shims under the radiator rot out or are removed, which levels out the radiator and also lowers the feed pipe. If the feed pipe leaves the radiator and then goes down through the floor, lowering the radiator inlet lowers that next joint and can level (or tip the wrong way) the next horizontal stretch of iron. In our house I didn't realize until too late that replacing the floors also lowered them by about an inch. We had horrible banging until I figured out what had happened, and I had to put the radiator on 1 shims to get the right angle on the feed pipe (it's either that or re-plumb the steam system; no thanks). posted by at on February 11, 2009 [