Why Is My Cylinder Making Loud Banging Noises?

The most likely cause of a loud banging noise from your water cylinder is build-up of sediment at the bottom of your cylinder. All water contains at least some degree of sediment – dissolved minerals from the earth. Over time, these settle out to the bottom of the cylinder and begin to build up. With enough time, the sediment can become thick enough that steam may build within it. When steam bubbles release, they can cause loud noises.

The solution to this issue is to have your cylinder drained and flushed regularly. It should be part of your annual maintenance, actually.

Water hammer is a phenomenon unique to indoor plumbing and it occurs in very specific situations. If you notice that you hear the banging noise from your cylinder or pipes after flowing water has shut off, chances are good that it’s water hammer. What happens is simple – when the water heater is full, the inlet valve closes. Then, all the water flowing through the pipes crash into the closed valve, which can shake the pipe and make a banging noise.

Fixing the problem usually means draining your home’s water supply (cutting it off at the mains and then opening a tap to let it all drain out) in order to recharge the air chambers. Note that this is most common with older homes. If you have a newer home, it could be that a water hammer arrestor has failed, or that you need them installed within your pipes.

Finally, you may hear a banging noise if your water pressure is too high. Note that this noise will not come from the water cylinder, but from the piping within your home. Overpressure situations within your pipes can cause them to rattle and bounce, creating banging noises. The solution is to reduce the pressure of water entering your home, and this is something that should be handled by a professional plumber.

If you’re experiencing banging from your water cylinder, it is best to call for professional help.