Washing machines may have artificial intelligence, washing and drying in the same unit, as well as quick drying or energy saving, but they are still far from perfect due to the sounds, bugs and even leaks that occur from everyday use and that we are still far from being able to solve.
Within this context, one of the biggest doubts regarding washing cycles is the “knocks” that sometimes come from inside the washing machine. One of the most famous is the one that occurs just after the tub fills up and that sounds like powerful but short crackling. This sound is known as water hammer and it is more common than it seems.
What water hammer is and why it happens
You are filling the washing machine drum and when you finish you hear a banging sound, as if something had broken from nowhere. You are startled, but after a few seconds the washing machine continues its cycle normally; you let it go. If you don’t know what causes it, the most important thing is to know that this is known as water hammer.
This shock is caused by a sudden increase in pressure in a pipe caused by a rapid variation in flow velocity. In other words, the phenomenon occurs when a liquid circulating in a closed system is forced to stop abruptly or change direction, such as when the washing machine is at its limit and closes its valves. The shock spreads throughout the system and multiplies at first, causing an increase in pressure.
It is important to mention that water hammer does not only occur in water, but also in other incompressible liquids and gases. You should also consider that the pressure shock often leads to vibrations or a tapping noise that is repeated before the pressure drops. This is why, sometimes, we also talk about a hydraulic ram. Although pressure shocks can be heard, they are difficult to measure, since the pressure shock is established and decreases in an extremely short time.
As we have already said, the causes are the rapid opening and closing of valves, the starting or rapid disconnection of pumps, but it is also due to the disconnection of the water column or pressure buffering that causes this negative effect. Another point to note is that systems designed in such a way that the continuous flow is interrupted, and also carry a greater risk. For this reason, as far as possible, elbows and sharp variations in pressure should be avoided.
What are the solutions to this problem?
Before thinking about solutions, you should know that the main reason why you should fix this problem is because it could cause leaks, deformation or destruction of valves, breakage of pump rods, breakage of impellers or leaks in pipes. Therefore, the ideal solution would be:
- Check that there are no loose pipes or connections to reduce the effect of water hammer.
- Install air chambers in your drainage system, i.e. these vertical pipes installed near the water valves that serve as shock absorbers for the pressure surges that cause water hammer. However, they must be constantly maintained.
- Open and adjust the water pressure when washing, because if you don’t have full pressure, the water hammer will have a minimal effect.
- Maintain the pipes.
- Install water hammer arresters to absorb shock waves.
