I never flushed a radiator. I know my aunt used a key on hers years ago. The house I'm living in doesn't have a key, there is a valve screwed in.
But, there isn't a steam release on the valve. I'm going to buy a steam release valve to use. The question is ... When do I perform the release?
Do I wait for the steam to build up and then open the valve or if I open the valve will the condensation come out? What is the safest way?