Why does my water heater make banging nosies when heating up?

Answer 1

I'm a plumber, and the correct answer is, the water tank has sediment in it, which in normal, but there is a build up of sediment that is making it hard for the water heater to do its job properly. The heat from the burner is making the sediment bubble up, and that is what you hear. You can clean the tank by turning the cold water supply to the tank off, draining the tank completly fron the drain at the bottom of the tank, then turning the cold water supply on & off to "stir-up" the junk on the bottom of the tank. Make sure the gas is turned to 'pilot' position before you do anything.

Answer 2

The answerer who said it has sediment in bottom of tank is correct. It is usually lime if you have well water. The stuff in the bottom is percolating. The water tank needs to be drained/flushed or it will only get worse and the heater will eventually cease to operate. Here is a link to follow if you want to drain it yourself and more explanation on why water heaters get sediment in the bottom:
http://www.naturalhandyman.com/iip/infwaterheater/infdrainwh.html

Answer 3

Because you have sediment on the bottom of the tank. Try connecting a hose to the drain valve and flushing the tank. If your tank is an old one you might want to think of replacement.

Answer 4

because there is sediment on the bottom of the tank to correct this flush out the tank from the bottom dont run dry should take care of problem

Answer 5

This is simple expansion and contraction from heating up. You can solve some of this by bleeding all your radiators and your supply tank. Do this when the pump is on.

Answer 6

Because the expansion tank has too little air in which the hot water can expand. Check it and empty it and have it reset.