We just bought a house with a 10yr old 40gal natural gas water heater. When it heats the water it almost sounds like its percolating loudly. I can hear the banging from the second floor. I was told it might be because its over firing. I was just looking for another opinion.
Thanks
Matt

Calcium build up in the bottom of the tank. Let me know if you need to know how to try and clean it out.

If you could I'd greatly appreciate it.

1) Turn the gas valve to pilot.
2) Turn the water valve coming into the cold water side of the heater off.
3) Connect a garden hose to the drain on the bottom of the water heater and open it up.
4) Open all your hot water faucets
5) Drain the tank all the way down.
6) Close the faucets.
7) Open the cold water fill valve you closed in step 2
8) Let the tank fill back up again.
9) continue draining the tank through the garden hose for 10-15 minutes.
10) Close drain valve and remove hose.
11) Remove the aerator from 1 of the faucets and open the hot water to purge all the air.
12) Put the aerator back in and purge the air in the same manner from other faucets. This prevents the aerator from getting plugged up from all the loosened calcium.
13) Turn the gas valve back to on.

Hopefully this will get the majority of deposits out of the bottom of the tank.
You run two risks that can be a real pain, sometimes the drain valve gets plugged with deposits and won't drain or the valve won't close tightly when you close it again.

This may need done again in a few months and every year or so after, depending on the hardness of your water

Good Luck

Thank you very much!