Mixer tap
A mixer tap or mixer tap is an outlet tap (colloquially often referred to as a water tap ), which also functions as a mixing valve for hot and cold water . Usually it is controlled by handles , levers , button presses or motion sensors.
The most common use of mixer taps is on taps , with which the water flow is metered and the desired temperature is achieved by mixing cold and warm water . The following are sometimes integrated as additional functionalities:
- Stabilization of the mixing temperature, even in the event of pressure and temperature fluctuations in the inflows, by means of a thermostat , see thermostatic mixing valve
- Switching valve between the swivel arm / outlet and the shower connection.
Household mixer taps that are used in a washbasin or kitchen sink (instead of being attached to the wall) usually require a circular cutout with a diameter of 28 to 32 mm. Mixing fittings with an extendable outlet head often require a cutout with a diameter of at least 35 mm, since in addition to the cold and hot water inlet, the inlet to the flexible supply line and the flexible line itself have to be passed through the cutout. In sheet metal sinks, the cutout is often made with a simple tool called a screw punch, sheet metal punch or (screw) hole punch and is usually suitable for sheet metal thicknesses of up to 1 mm, more rarely up to 2 mm.
Low pressure valve
Only low-pressure fittings can be used to operate a pressureless boiler. They also consist of two valves. The cold water valve drains into the common outlet. The hot water valve directs cold water into the low-pressure boiler, from which the preheated water flows freely to the common outlet. The connection between the boiler and the outlet is always open and must never be shut off (no aerators, no shower stop). Dripping when the boiler heats up is normal and is due to the expansion of the water when it is heated. Throttles are often installed in the inflow, which protect the boiler against overpressure depending on the water pressure or the flow of the feeding line. Low-pressure fittings can be recognized by the fact that they have three connection lines: one is the cold water inlet, one brings cold water to the boiler and one leads warm water from the boiler to the outlet.
The cut-out for a low-pressure fitting that is used in a wash basin or kitchen sink usually has a diameter of 32 mm.
Single lever mixer
Designs with only one operating element for regulating be as lever mixer , single-lever mixer , single-lever mixer , single lever or single-lever mixer , respectively. This design, the functional core of which is now a so-called cartridge, was developed in the 1940s by the American Alfred M. Moen .
There are two flat-ground ceramic discs in the cartridge, which can be moved and rotated against each other.
The fixed ceramic plate of a mixer tap has three openings, one of which is connected to the hot water and cold water inlet and the outlet of the faucet. The lever, which can be rotated and swiveled up at the same time, moves the second, movable ceramic plate into which a single recess is incorporated. Depending on the position, the recess slides over two or all three openings of the fixed plate and allows the water to flow through.
Since the actuation travel of single-lever mixer taps is very short, pressure surges occur when the valve is closed quickly , which in unfavorable cases can damage the pipe network and lead to disruptive noises.
Since water can often remain in the cartridge even after the water has been shut off and drained from the supply lines, single-lever mixers are not frost-proof. Often, the fitting can only be emptied after dismantling to such an extent that the cartridge is not damaged by ice formation.
The sealing of the inlets against the drain is achieved by the flat and smooth surface of the ceramic discs, which are pressed together in the fitting under slight pressure.
The entire ceramic cartridge is usually replaced for maintenance or repair.
When used in low-pressure fittings, the cartridges are the same, but the waterways are different from what is shown in the picture: the cold water still reaches the outlet directly, but the hot water valve directs cold water to the boiler, from which it comes back without pressure and directly in the outlet is admixed.
Thermostatic mixer tap
Thermostatic mixer taps as shower, bathtub or basin fittings allow a constant outlet temperature of the mixed water, independent of the temperature and largely independent of the pressure of the water supply lines.
Inside, the mixer thermostats have a regulator around which the mixed water flows. The regulator consists either of bimetallic wire that is wound into a helical spring , or a paraffin -filled capsule, a so-called wax expansion element. Both types of controller perform proportional changes in length when the temperature changes, whereby the version with bimetal wire can describe larger control paths. If the inflow conditions change (temperature, quantity), the controller shifts and opens or closes the slots in the hot and cold water inlet pipes.
The hot water temperature can be kept constant apart from a deviation of one degree Celsius from the target temperature . As anti-scald thermostats are usually equipped with a locking mechanism on the control lever must be unlocked to select from more than 38 ° C. Some thermostats also have a water-saving button that must be pressed in order to set the full flow.
As a rule, there are non- return valves in both the cold and hot water supply in order to avoid a hydraulic short circuit between the cold and hot water network, which would otherwise connect the two networks in the thermostatic mixer tap.
There are special designs in which the mixing chamber is surrounded by cold water on the outside, so that the fitting always remains cool from the outside.
literature
- F. Kotschi, P. v. Entremont: The electric hot water tank. Published by Julius Springer, Berlin and Vienna 1931, p. 33 ff.
- Karl Volger: House technology . Basics - planning - execution, BG Teubner, Stuttgart 1999, ISBN 978-3-322-94100-8 .
Web links
- Installation instructions for mixer tap (accessed on February 25, 2016)
Individual evidence
- ↑ Honeywell GmbH (Ed.): Technical catalog house technology. Safety and control fittings - water fittings . Mosbach 2011, p. 9 ( online [PDF; 5.8 MB ; accessed on March 21, 2013]). online ( Memento of the original from March 8, 2016 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
