I have a loop of 3/4 and 1/2" copper pipe that makes a slight hammering sound while being used and sometimes when unused but perhaps the hot water heater fires up and pipes hammer. It is not a real loud hammer and it does not bother me but my only concern is, could this slight hammering cause any damage?

It's on the hot water side and this loop also has a gravity return so that hot water can circulate and get hot water to a distant end of the house sooner. And it works without a pump.

Bs5

F 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. You might want to consider cleaning the screens on your areators if you have a high mineral buildup. If thev 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, Tom

Thank you Speedball. Was I ever glad you told me about that. I just got done unhooking the hose from the boiler drain at the bottom of the water heater and over to the floor sump where I drained the flushed water. I blew out lots of calcium as this old well water is actually 120 grains of hardness to the gallon. I will be doing this on a regular basis now thanks to you. I hope that this quiets my pipes down for a while. Thanks again.

Bs5