In an effort to get to the bottom of this, Oliver has put together a special mixed audio clip of HIS OWN bedroom noise, and we went looking for answers...
We open this post up for more help on the matter.
Over at Time Out, they have a list of Top Winter Mysteries Solved, and one of them is the steam hammer, however, their answer is not great:
Condensed water in a radiator gets thrashed around violently when a new head of steam rushes up, causing that hard-to-ignore death rattle. The solution: Place a shim under your radiator to tilt it, allowing the condensation to drain back into the boiler. Or move to a building with central heat.
Over at Parker Holsman in Chicago they got a little more specific and have more solutions:
The banging noises are caused by steam forcing its way through pockets of water. Three problems usually cause these banging noises:
1. People are trying to regulate heat by partially closing or opening the steam valve.
2. Radiator is tilted in the wrong direction.
3. There is a worn-out seat in the steam valve.
To correct these banging problems:
1. For problem one, it is important that radiators always be completely turned off or on. Any partial closing not only causes banging but also results in leakage, damaging your floors and the apartment below.
2. For problem two, a shim is usually placed under the two radiator feet fartherest away from the steam valve, tipping the radiator slightly toward the steam valve (about 5 degrees) to allow the condensed steam to drain back toward the boiler.
3. For problem three, professionl help will be required as the steam valve will have to be replaced.
Obviously, this is not going to help you in your apartment buildind, so we dug further... over at Terry Love's Message Board we found out this useful DIY tip for correcting your own radiator. This is as far as we got:
Just before the steam enters the radiator, it passes a shut off valve, and an expansion relief valve. Turn off the valve to that banging radiator, remove the expansion valve, and soak it overnight in vinegar. Rinse and replace it, and turn on the steam. Does it still bang, but not as bad? If so you have a hard water calcium deposit built up in the radiator, and it captures air in pockets that are irregularly being displaced by hot steam. You could try to clean the radiator with vinegar (or hard water calcium deposit remover [or muriatic acid]) but a wiser bet is to look for a replacement radiator.
Obviously no one has written about how to solve this problem if it's just a pipe running through your bedroom and the culprits are four floors below.
(First published 2006-01-11 - MGR)