Check valve - what is it and what is it used for?

Check valves, also known as non-return valves, ensure that water or gases can only flow in one direction. They open automatically in the direction of flow and close automatically as soon as the flow direction begins to reverse. Typical applications for check valves include mixer taps, gas lines, and radiators. The valves consist of a disc and a spring. The disc presses against the spring in the direction of flow, thus opening the pipe cross-section. If the flow stops or reverses, the pressure on the spring ceases, and the pipe cross-section is immediately closed.

Check valves in mixing taps

In mixer taps, check valves prevent cold and hot water from mixing. Such mixing is not only energy-inefficient, but lukewarm water also provides ideal living conditions for bacteria. To shorten the distance between the check valve and the point of use, the valve is generally installed close to the tap. It is usually located inside flexible PEX tubing.

Low maintenance intensity can lead to malfunctions.

Today, the mixing of hot and cold water primarily occurs before the shut-off mechanism. A physical separation of the hot and cold water lines therefore does not take place – even when the tap is closed. Due to pressure differences between the two lines, the hot and cold water mix. As a result, we only get slow-flowing or even stagnant lukewarm water. Check valves are supposed to prevent this. However, in practice, these are rarely, if ever, maintained. This can lead to limescale deposits and other impurities, and consequently, malfunctions.

The closing mechanism in front of the mixing chamber eliminates the need for non-return valves.

France is breaking new ground with the French standard NF 077 MM. This standard mandates the closing mechanism be located upstream of the mixing chamber. Positioning the closing mechanism upstream, thus eliminating the need for backflow preventers, would represent a significant revolution for the fittings market, as the majority of current electronic or thermostatic fittings do not yet meet this requirement. Our partner Delabie has developed a unique, patented system that ensures the hot and cold water inlets on thermostatic faucets are shut off directly at the connections. This eliminates the need for vulnerable backflow preventers and completely prevents the risk of backflow of hot or cold water from the faucet. More information on how the new cartridges work can be found below.