: We have a baseboard hot water heating system, with 2 zones. When the heat comes on, the pipes knock. This is especially loud at night. I need to know how to safely bleed air out of the system. Is there something we have to do to the pressure valve? I remember the areas to attach the hose, but is there more to it than that?My hot water system has small bleeder valve on each radiator. If yours has these, I would start at the highest radiator, and bleed them one at a time just enough to get the air out.
