OK, so it's been a long time since I've enjoyed steam heat. And at that time, I wasn't responsible for maintaining it. Now, I am.

I went to my local hardware store, and bought 3 new valves for the radiators upstairs. The nice guy that runs the store told me I needed model "6" for upstairs. 5 is for downstairs, and 4 is for the room with the thermostat in it. Sounds good. I don't know what the previous homeowner did, but he had a variety on the radiators upstairs. I can't tell if they were the right models or not, but some were round, some were like a cylinder. Some had holes in the top, some seem completely sealed. The new ones are all round, and all have a hole in the top. Steam, obviously, escapes through this hole. It's a slow spray. It definitely made the radiators quieter, to just a simple hiss instead of the obnoxious sniffing noises they made before.

Question 1 - any reason why some have holes, and some do not?

Also, I bought a replacement connection from the pipe to the radiator for one of the ones downstairs, because the handle is not there. so i figured, rather than turning it by hand with a tool every time, i'd just get a replacement. I don't have the proper wrench to do it, so I'll pick that up.

Question 2 - any benefit to replacing these valves? I was watching on This Old House that it's good to go in there, clean it up, and replace the washer (he used a liquid or something instead of a regular washer).

Question 3 - What are these thermostatic radiator valves? are they worth it? can i install them myself?

Thanks!