In the last week or two we have been having an unidentified rattling in our house that sounds like plumbing pipes rattling. The problem is we are on city water and do not use a water pump. It doesn't happen when water is turned off/on. Or when anything that has to do with water is being used. We have natural gas as heating for both our house and water heater, could this have anything to do with it?

It is intermittant and I try to listen for when it comes on because it comes only on one end of the house. Any ideas.

I think maybe hot water heaters can do that. I forget exactly what is going on. They will run for a while after you use hot water, and sometimes if they just sit too long.

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. 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