Best Of

That WAS a two pipe steam system. It is now a bodge job. The original concept was that the steam was supplied by a boiler, at rather low pressure, and arrived at your radiator, where it condensed and heated the room. The air was released from the radiator through the trap on the right-hand side of your radiator and made its way back to the boiler Very simple. Very quiet.

I agree that it is likely the shiny silver vent was put on because the trap failed. They do if the system isn't maintained. This means that any condensate probably has to try to make its way back to the boiler through the inlet. Now someone decided to put a TRV on the inlet. It may or may not be a correct TRV from a steam system — but unless it is a very unusual one, it is installed in such a way as to almost guarantee to restrict that condensate flow. This will trap condensate in the radiator, and when the TRV opens, it will make objectionable noises.

As a renter there really isn't all that much one can do about it all. Try to get your building manager to get a steam heating person in to examine the whole system; it is unlikely that your installation is the only problem with the system…

There's probably nothing you can do. Somewhere there is water pooling in the steam supply pipe (the one on the left). It is likely under the floor. The problem has to be solved by a steam professional hired by the building management. The pitch of the radiator is not going to affect this.

When the heat is likely reduced at night, and this allows that pooled condensate water to cool. Then when there is a call for heat in the early morning, the steam comes into contact with that cool water and it causes the steam to collapse which flings the water against the pipe, causing that sound.

Now that vent on this two pipe radiator is a sign that something is fouled up. And ironically, that might help you. You could rotate the vent so that it's upside down and see if that makes the sound stop. If it does, it will also probably prevent steam from entering the radiator so it may make your room cold.

You could also try adjusting the TRV on the left side, turning it all the way down, but I don't hold out hope it will help much.

The return is dry until it comes down to level with the water line and will warm up much more quickly as it is empty. Below the level of the water line the return line is full of water, and the hot condensate drips are diluted. By the time it gets near the Hartford loop it could be cooled off. Warm condensate is a trickle. The water filled return piping is gallons, therefore any temperature change in the return piping is very slow and gradual. Can not use temp. variation to diagnose a clogged return. Most steam water line issues are due to contaminated water. Skimming is often the answer.