I have a raised ranch with heated finished basement. Two zones with zone valves,one circulator. The system is natural gas hot water slant fin. The basement heat is quiet and OK. The main floor, even after several air purges still banging away. I replaced the main feed fill regulator valve,thought the pressure to the main floor might be low.Still bangs very loud.What else could be the problem? Could the expansion tank have anything to do with it? How would I know if the circulator is OK or not? Any suggestions? Thanks Tony M
Try to find the source of the bang. Check if it is happening when one of the zone valves closes. You can do that by raising both thermostats for two minutes, then turning one down to listen for the bang. Get back with the information.
It only happens when the main floor zone valve is open and the circulator is running. It is not just one bang,but several bangs,one after another. It stops after about five minutes or when the zone valve shuts off.
Harold, I finally just opened up the ceiling and found that the holes in the joists were too small. Enlarged the holes and noise is gone. You would think that experienced plumbers would know better and make the proper size holes during the installation. I guess there are good and bad mechanics in all professions.