i have baseboard heat-my problem is that some of the rooms get very hot while some not at all-there is a valve where the pipe coming from base through floor to each baseboard unit. What does this valve do? does it controll te amount of water running through the pipe or what. not all the pipes coming up from basement have this valve. i don't want to turn it without knowing what it does. you can hear the water or what ever it is sounds like it's running or dripping through the pipes but some are not heating up. there is also a lot of popping and cracking sounds when the heat is coming on ( i think ). hope you can help. last winter my heating bill was out of this world. PLEASE HELP. any suggestions or better yet easy fix is appreciated THANKS