I live in an 8-unit building that has it's own water heater but shares a boiler with another 8-unit building for the hot water heating system. I hear this thumping/banging type noise off and on at all hours of the day/night but not necessarily at the same time every day and not sometimes not as loud as other. I have tried to get the management company to do something about it but when the maintenance man and/or caretaker come to the building it is, of course, not making any sound so they can pin point where it comes from. The boiler and water heater are upstairs in a locked room. The water softener is downstairs in our laundry room. When I hear the sound I am unable to figure out where it comes from other than it sounds like it's coming from the common wall I have with the laundry room which is below the boiler room. This has been going on for over a month... possibly even 2. There is a pipe chase than runs through the ceiling in my unit for the 4 units at this end of the building but it doesn't seem to come from the chase; although every once in a while I do hear noise in there for a short time when water is being run but not all the time. Is there anything I can do or say to get this taken care of... to get a license plumber out here to check it out or whatever. They seem to be more reactive than proactive and I am concerned that my unit will be damaged if it not repaired in a timely manner.

Gas or electric water heater? If it's gas I may have solved your mystery. Cheers, Tom

I believe both the boiler and water heater are gas.

If you do not flush,(not drain) your heater on a regular basis it will build up mineral on the bottom of the tank. When the flame comes on it turns the water trapped under the mineral to steam and the steam escaping is what you hear. Let me show you how to flush your heater. Attach a hose to the boiler drain at the bottom of the tank. With the pressure on, open the boiler drain and let it run until the water runs clear. You will see a spurt of red,(rust) and some white grains,(lime or calcium carbonate). The whole thing shouldn't take more then a few minutes. Don't forget to flush it out every month. Your heater will thank you for it. . If the problem still persists after you have flushed, you will have to drain the heater, remove the boiler drain and go up in the bottom of the tank with a wood or plastic rod, (not metal) and try to break up the mineral and flush it out. Good luck and thank you for rating my answer, Tom