Bleed the radiator, should be nearly silent if running properly (Only hear the water pump and boiler fan when near the mechanical room). Air in the lines is very bad, not only does it reduce the efficiency (amount of heat released), the bubble acts like a little chisel on the inside of the pipe (thus the clunk/ping sound). Usually you just need to worry about the highest radiator(s), as I find the first floor ones bleed right away, but the second floor ones usually “catch” the air and take a few seconds to bleed. Always bleed at the beginning of the heating season to avoid any problems.
Bleed the radiator, should be nearly silent if running properly (Only hear the water pump and boiler fan when near the mechanical room). Air in the lines is very bad, not only does it reduce the efficiency (amount of heat released), the bubble acts like a little chisel on the inside of the pipe (thus the clunk/ping sound). Usually you just need to worry about the highest radiator(s), as I find the first floor ones bleed right away, but the second floor ones usually “catch” the air and take a few seconds to bleed. Always bleed at the beginning of the heating season to avoid any problems.