What is the purpose of a check valve in a washing machine?

A check valve, or anti-siphon, is a part of the drainage system that prevents water from entering the machine from the sewer pipes. This part is usually made of durable plastic and is connected to the drain hose. It's included with most modern washing machines, but sometimes you need to purchase one yourself. What is a check valve for, and how do you install it?

Purpose of the valve

When asked why a check valve is needed, experts note that installation isn't always necessary. It can be omitted if the device is connected to the sewer system and meets all technical requirements. Installation of a check valve is mandatory in two cases:

• When connecting to the drainage system. When the washing machine is connected to the sink's drain trap, a "siphon effect" may occasionally occur, with waste water flowing into the washing machine.
• If the machine's drain hose cannot be positioned at a sufficient height, a "siphon effect" cannot be ruled out in this situation.

Important! The drain hose must be at least 50 cm above the drain level.

Only under this condition can a check valve be easily avoided. Waste water will not flow back into the machine.

How does the valve function?

The principle of the anti-siphon is as follows: when dirty water is drained, the valve opens under the pressure, allowing fluid to pass through easily. When the water runs dry, the pressure drops. The check valve closes automatically, without external assistance, preventing dirty water from entering from the sewer pipes. A ball-shaped polypropylene part acts as a shut-off mechanism. There are different types of anti-siphons for washing machines.

1. Disassemblable. The part can be easily disassembled and cleaned if clogged. These valves are often installed in areas with hard water.
2. Non-detachable. The most common model. It's made of plastic, so it's inexpensive.
3. For the sink trap. The valve's name speaks for itself: it's installed in the trap where the sink is located.
4. Cut-in. To install into a sewer system, the part is cut into the pipeline.

Wall-mounted valves are also available. They are the most expensive of all the available options, but they have a more aesthetically pleasing appearance.

How to install the valve?

When installing a check valve yourself, it is important to take into account the design features of the model. However, the general rules for connecting all types of anti-siphons are identical. A check valve is a complex tube with various outlet diameters. One end of the part is installed in the sewer pipe or trap. The other end is attached to the machine's drain hose.

Both connections must be carefully sealed to prevent leaks. This is sufficient to prevent water from the sewer system from entering the washing machine.

   

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