Check the position of every radiator in your heating system. Each radiator needs to have a slight slope towards the steam inlet pipe. This pipe is connected to each radiator through either the floor or wall. Be aware that if there is no slope to the position, install a ¼ inch piece of wood under the feet of the radiator. This will put an end to the irritating noises that come out of the furnace.
Check the vents
After that, make sure the vents are unblocked. Rust, corrosion or something blocking the flow of air will not let it function properly. The air should pass through properly in your steam heating system. If the air flow does not move properly the air will get trapped inside the radiator and will not let steam enter. Moreover, if you see a blocked vent, then get it from a local hardware store. Also, let your steam heating system to cool down before you unscrew the vent to replace it. Check if your inlet valves are all the way shut or open as this will help prevent noises in the heating system. The position of the inlet valves will assist to regulate the heat.
On the other hand, check for leaky valves. If you see steam going through an inlet valve, it is normally caused by the cap nuts being loose. These are big nuts and can be found at the horizontal and vertical pipe connections. You should be able to tighten the nuts with the help of a wrench. Remember to make sure that you take your time and do not rush anything.