Is it worth the while to close off a bedroom heat register in a room I dont use and keep the door shut. I have Hot Water Heating. Approx 30 year old unit. It runs good. But is it worth turning the valve off to try and save a few bucks. Will this also effect the way the unit works. And how often should you go around and bleed the air out of each register. I dont have those big cast iron ones mine are like metal fins with a couple pipes running through the middle of them. Is anyone familiar with this kind. thank you anthony