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Dishwasher in the household

A dishwasher ( Switzerland. Also dishwasher as shorthand also dishwasher or ugs. Dishwasher called) is usually in kitchens employed device for automatic cleaning of cooking and eating utensils , cutlery and kitchen utensils .

Inside a dishwasher - 360 ° photo Display
as a spherical panorama
Empty dishwasher (basket removed) with salt corrosion stains on the bottom

According to the Federal Statistical Office , 71.5% of private households in Germany owned a dishwasher in 2017.


Dishwasher from 1917

In 1850 Joel Houghton was granted the first patent for a hand-operated wooden dishwasher, but it worked poorly. In 1865 L. A. Alexander also received a patent; his device did not work properly either.

In 1886 the American Josephine Cochrane (1839–1913) submitted a patent for a water pressure dishwasher. She is considered the inventor of the dishwasher. The first dishwasher was presented at the Chicago World's Fair in 1893 . Cochrane formed a company, Cochran's Crescent Washing Machine Company , which launched the KitchenAid line; Customers were initially restaurants and hotels. In 1926 the company founded by Cochrane was bought by Hobart .

At Miele , 1929, the first electric dishwashers in Europe were built. For private households, however, dishwashers did not gain acceptance until the late 1960s.


Glass model of a dishwasher in operation

According to Sinner's Circle , the interaction of the factors time, mechanical energy, temperature and chemistry cleans the items to be washed. Rotating nozzles spray or spray the strongly alkaline soapy water against the dishes. Here, the high are pH-value of the liquor, the degreasing surfactants (and possibly in the detergent contained starch - and proteolytic enzymes as important for dissolving the food residues such as temperature, reaction time, pressure and flow rate of the water jets).

Dishwashers have several washing programs that differ from one another in terms of duration and temperature range. Wash programs are divided into a pre-wash cycle (cold water without detergent) to remove easily removable food residues, a main wash cycle (temperature approx. 30 to 70 ° C with detergent) and a final rinse (temperature approx. 65 to 85 ° C). The wash ware is cleaned in the two wash cycles, while the final rinse cycle is used to remove the contaminated wash water and dry the wash ware. It also prevents the formation of limescale and water stains.

When using a dishwasher, in addition to water and electricity, machine dishwashing detergent , rinse aid and regeneration salt are consumed, which are filled into containers (with closable lids) in the interior of the machine. Washing-up liquid is available in powder and gel form (especially in the USA) or as tablets (tabs). At the beginning of the wash cycle, the detergent dispenser opens and the dishwasher detergent, provided it is powdery or liquid, is immediately distributed in the interior, tablets take some time to dissolve. Liquid rinse aid prevents stains from forming during the drying process by releasing the surface tension of the water. With hard water, regeneration salt is needed to regenerate the machine's ion exchanger , which softens the water , preventing the formation of lime soap and scale deposits in pipes and on heating elements.


After switching on, water is let in or pumped in from the water supply network. With the help of an impeller, floats or pressure sensors, the incoming water volume is measured and limited. The fresh water reaches the pump sump , which is located at the bottom of the dishwasher , via the softening unit . From there, the water is pumped up and sprayed over the items to be rinsed using moving spray arms, which are driven by the spraying water .

Rinsed, water-insoluble substances are filtered out with the help of two sieves that cover the pump sump. The first sieve filters out the coarse impurities. Under the first sieve there is a second sieve with which fine impurities are filtered out of the water. The filtered water is pumped back to the spray arms in a circuit. Next to the second sieve is a container for temporary storage of the filter material, which is vacuumed off after the second wash cycle.

In the second rinse cycle, the detergent is added to the rinse water; an alkaline solution is created, which is heated to the set temperature in the pump sump. This is distributed over the items to be washed in the main wash cycle (second wash cycle). Insoluble impurities in the water are still filtered out.

In the last rinse cycle, rinse aid is rinsed out of a previously filled chamber when using individual components. The rinse aid reduces the surface tension of the water, which makes it easier for the items to run off.

After the last rinse, the contents are dried. There are different drying systems for this:

  • Heating of the rinse water up to 75 ° C; the resulting inherent heat of the cleaned goods and the evaporation effect can lead to a good drying result.
  • In the case of devices with blower drying, the moist air is drawn out of the device.
  • Drying with a closed circulating air condensation drying system: a fan guides the warm, moist air through a cold water-filled heat exchanger in the side or rear wall of the device, where the moisture condenses.
  • Internal tubular heating elements in older devices heat the air by means of heating pulses during the drying phase.

In addition to widespread household dishwashers, which typically have maturities of up to 3.5 hours, are dishes to be washed, such as in hotels, restaurants, nursing homes, hospitals and in large kitchens with significantly more frequent and rapid catering , industrial dishwashers used whose running times are usually between one and five minutes. This short program duration is sufficient, as the dishes are usually washed immediately after use and therefore no dried-on dirt has to be removed. In dishwashers with a continuous conveyor belt, pre-wash, main wash and drying take place in different sectors.

The chemicals used for cleaning stick to the dishes in traces and are carried over to the next wash cycle or wash as a “ carry-over effect ” via the liquid residue remaining in the pump sump. Because surfactant residues remain on the glasses even when using rinse aid, beer glasses are often pre-rinsed before filling in order to remove the surfactants and thereby extend the shelf life of the head of the beer. Over time, detergents can form a film on the glass, which makes it almost impossible to form a head of foam.

Comparison with manual flushing

According to a study published in the International Journal of Consumers, which was sponsored by the industry, washing a place setting by hand would require an average of 49 liters of water and 1.7 kWh of energy, with a certain dishwasher tested only 13 liters of water and 1, 3 kWh of energy. Other authors point out weaknesses in the study:

  • Depending on the way in which the water is heated, the consumption of final energy can improve with manual washing;
  • It was not taken into account that detergents for the dishwasher are usually “harsher” than hand washing-up liquids
  • The 12 place settings according to EN 50242 (a standard machine load ) used both for hand washing and washing with the machine are rarely used in practice. When washing smaller quantities, the specific consumption of water, energy and detergent per place setting increases, both with hand washing and with dishwashers.
  • The option of having dishes cleaned by the machine can mean that a household produces more dirty dishes because you don't have to do the washing yourself.

"Washing with the machine needs on average 50 percent less water and 28 percent less energy than hand washing," according to a study funded by four household appliance and detergent manufacturers.

On the other hand, the Association of Energy Consumers came to the opinion that energy-conscious washing by hand would use "up to 70 percent less energy, detergent and total costs and about the same amount of water" ; But “for the majority of households, the dishwasher is probably more economical in terms of water and energy consumption than washing by hand.” Some dishes are not dishwasher-safe, i. That is, it does not tolerate the commonly used aggressive cleaners and high temperatures; therefore it must be rinsed by hand (see below ).


Up to the mid-1990s, electromechanical program controls were common in dishwashers , similar to those in washing machines. These consisted of a rotary knob which, depending on its position, opened or closed different contacts to the components of the machine (heater, pump, etc.).

To start a program, turn the program knob to the appropriate mark (which means it was on the first step of this program) and then switch on the machine. Once a program step had been processed, the knob was turned further using a stepper motor . Different programs were therefore only possible to a very limited extent, insofar as the program steps of all programs could be arranged on the switchgear. Often such machines had the following three programs:

  • Normal program with pre-wash (heavily soiled dishes)
  • Normal program without pre-wash (normally soiled dishes)
  • Pre-wash.

With some models, however, a selection of the temperature was already possible.

From the end of the 1990s, the mechanical program control mechanisms were replaced by microprocessor-controlled components, which enables different flushing programs. Frequently during this time were z. B. an intensive program with a high temperature (e.g. 65 ° C), a "normal program" with usually 55 ° C, a short program with a lower temperature and a "pre-wash" program. In dishwashers with electronic controls, the main switch must first be switched on and then the program selected. The actual program start then takes place by pressing the start button or (especially in the case of fully integrated dishwashers) by closing the appliance door.

With more modern dishwashers, the programs changed again significantly. On the one hand, they usually last considerably longer than before, since a considerable saving in energy can be achieved by reducing the temperature and the amount of water. In order to achieve the same cleaning result, the water remains in the machine longer. On the other hand, a "normal program" in the classic sense is often no longer available; The eco and automatic programs that are available instead are now the usual programs for normally soiled everyday dishes.

The program selection varies depending on the manufacturer and model. However, current dishwashers usually have at least the following programs:

  • Eco program : an energy saving program that is commonly used as a reference for the energy efficiency class . In older dishwashers, the only difference between the eco program and the normal program was the lack of pre-wash. Today we mean something different: the temperature is usually around 50 ° C, the amount of water used is less than with other programs and the water works for a very long time to achieve the desired cleaning effect. Typical eco programs last more than three hours.
  • Automatic program : With automatic programs, the dishwasher continuously detects the cloudiness of the wash water. This allows conclusions to be drawn about the load and the degree of soiling of the dishes. The device adjusts the temperature (usually within the range of 45 and 65 ° C), the amount of water or the program sequence accordingly. The duration of the program is therefore variable and not precisely predictable.
  • Quick program : If this is to be reused as quickly as possible dishes to be washed, the quick program can be used. It washes at a higher temperature (usually 70 ° C) and takes about as long as the normal program of an older dishwasher, usually around 75–90 minutes. The energy consumption is considerably higher than in the Eco program.
  • Short program : Not to be confused with the quick program, as fewer rinse cycles are used and they take less time. The short program is used for dishes that are only slightly soiled, usually rinses at 35 ° C and usually lasts 30 minutes.
  • Pre-wash : rinse once with cold water to avoid odors if the dishes have been in the machine for several days (and the machine is not full enough for a complete wash program). This takes between a few and a maximum of 15 minutes.

The magazine test tested dishwashers and found in 2013 that on average a wash cycle with detergent in tablet form costs 48 cents in the quick program, but only 38 cents in the eco program, which would result in additional costs of more than 35 euros per year if the quick program were used daily .

Depending on the manufacturer, other special programs are offered, for example an intensive program for heavily soiled dishes, a gentle glass cleaning program or a particularly quiet night wash program.

Operation problems

Although the screens to separate most of the solids detached, it can still happen that lint from the detached paper labels or chipping of porcelain pass harness the wires and then constrictions, such as the nozzles become clogged. In most dishwashers, the spray arms can be removed without tools in order to clean the nozzles. Cleaning the sieves to remove any leftover food is part of regular dishwasher care; Otherwise the leftovers can start to rot and spread bad smells, which can also be seen on the cleaned dishes.

Too frequent use of programs that operate at a reduced temperature can cause grease drops to solidify, build up in the water circuit, clump together and other solids, which ultimately leads to clogging of a pipe in the circuit water network and the The machine's cleaning performance decreases or the machine blocks. The manufacturers therefore recommend cleaning the dishes at regular intervals using the program with the highest temperature in order to dissolve such fat deposits and to prevent emergency shutdowns when the machine is at a standstill. Pouring boiling water into the pump sump can sometimes resolve incidents at this location.

Oversized crockery or cutlery hanging from cutlery baskets can also block the rotation of the spray arms.

If the pump is not used for a long time, the water in the pump sump can begin to rot; a run at the highest temperature can solve the problem.

According to one manufacturer, corrosion can develop explosive hydrogen gas when standing for long periods in the water supply network of the house. To avoid accidents, the manufacturer recommends flushing the water supply network before using the dishwasher.

Pitting corrosion on stainless steel or aluminum in cutlery or on device components such as the inner walls can result from

  • steel alloys unsuitable for the purpose,
  • poor surface quality and improper processing of the steel,
  • Water with too high a chloride content , together with dissolved table salt from leftover food or residual solutions from ion exchanger regeneration,
  • acidic and / or salty food residues that act for a longer period of time before washing
  • too little detergent dosage,
  • a malfunction of the water softener due to regeneration salt carryover,
  • a badly placed or badly closing or torn lid of the salt container, which leads to salt being discharged,
  • Salt spilled during filling.

Residues after washing can be due to the fact that the dishes were in a " spray shadow ", that is, the water jets did not reach them sufficiently because the water jet was blocked by other items to be washed. Spinach and other herb residues stubbornly stick to dishes or settle again during the washing process and then stick to them; Such soiled dishes should be pre-washed by hand.

The ion exchanger, which pre-decalcifies the rinsing water, must be regenerated regularly; it is therefore automatically backwashed after each wash cycle with the aid of regeneration salt and can then bind alkaline earth metal ions again . If the regeneration does not take place regularly because no salt has been refilled, the ion exchange resin calcifies due to deposits (not chemical bonds) and is damaged in such a way that it can no longer be regenerated later. As a result, users have to rely on using a dishwasher detergent that contains a softener in the long term (otherwise the washing result will not be satisfactory). Advertising claims for machine dishwashing detergents like “replaces the regenerating salt” or “dishwashing detergent, rinse aid and regenerating salt in one” seduce consumers into permanently damaging the ion exchanger. Many manufacturers therefore reject guarantees when using such combination products.

Wash items not suitable for dishwashers

Antique dishes and cutlery are not dishwasher-safe. Valuable vases, old porcelain glazes, glass decor (metal decor) and drinking glasses made of cheap or older types of glass are not suitable for cleaning in a strongly alkaline environment at high temperatures. Glazes can get hairline cracks or chip off. Frequent washing in dishwashers can lead to glass corrosion in the form of milky veils on these glasses . A remedy against this type of corrosion is to sort the dishes according to the degree of soiling, if possible: glasses and other slightly soiled dishes go into a wash cycle that is operated at a reduced temperature with less aggressive detergents, heavily soiled pots and heavily soiled cutlery in one other. A low pH and salinity of the liquid and a high temperature accelerate the corrosion. Thus causes softer water in the dishwasher higher dissolution of minerals from the surface.

The information contained in the cleaners peroxide can cause in dishwashers purified domestic appliances, with rubber (for example, dough spatula or gaskets ) or the rubber seals of the devices embrittle and become brittle.

The prolonged rinsing with hot water can cause deleterious bisphenol A from polycarbonate containers (e.g., measuring cup, feeding bottle or blender cup) is dissolved (see baby food # dangers of baby food ) and this is distributed in tracks on the remaining items to be washed.

Containers, crockery and cutlery made of wood are leached out in the dishwasher, swell and become unsightly. Some adhesives that are used for bonding wood to metal or gluing wood to wood are loosened by hot water.

The paintwork can flake off on painted wood, as well as on painted vases or cups.

Thermoplastics can permanently deform at the high temperatures.

Clay such as terracotta, earthenware and other pottery can become dull in the machine and get scratched. Open-pored, unglazed clay also soaks up water during the long wash cycles; Subsequent heating in a microwave oven can lead to unexpectedly high heating of the material and burns if touched.

The detachment of burnt leftovers from heavily burnt pots can lead to the remaining sieve becoming clogged (because this type of leftover food is poorly water-soluble). Metal cutlery, especially such of silver, copper, brass and tin and alpaca , and bare parts of cutlery baskets can also corrode or during washing in a dishwasher color start , as many cleaner with peroxo have -Sauerstoffverbindungen (active oxygen) which cause this, or corrosion elements are formed under the influence of the alkalis . Some machine dishwashing detergents therefore contain corrosion inhibitors as antidotes , for example benzotriazole , which form a water-insoluble protective film on the metal cutlery.

Unalloyed aluminum reacts with both acids ( fruit acids from food and beverages residues, in some rinse aids ) as well as with bases . Then the surface of pots, pans and kitchen utensils (for example garlic presses or older meat beaters ) becomes matt .

Knife blades made of rusting carbon steel and non-corrosion-resistant and mostly magnetizable, ferritic knife steel can start to rust due to the conditions in the dishwasher (chlorides, humidity, temperature, organic acids in rinse aid and food and drink residues), chromium-nickel steels usually only on stress cracks , ceramic knives not at all . Corrosion of this kind also occurs with the spring steel of the spiral springs of poultry shears or older ice cream scoops .

In the case of antique cutlery with a so-called hollow handle, the blades or upper parts are fastened with a heat-soluble putty that can become soft or swell at the high temperatures in the dishwasher.

Temperatures above 80 ° C (with rinsing followed by drying and especially with commercial machines ) can temper steel alloys . This can reduce the hardness of the blade and lead to faster wear (see knife steel ) . Manufacturers of dishwashers and knives therefore partially recommend sharp kitchen knife not be cleaned in the dishwasher.


Due to their very different requirements, a distinction must be made between dishwashers for household and for trade / industry:

Household dishwashers

Dishwashers for private households are usually produced with a capacity of 12 to 14 place  settings in a device width of 60 cm (European standard EN 1116 ) or a niche width of 55 cm ( Swiss mass system ). Place settings are standardized in the European standard EN 50242 . So-called single dishwashers are generally 45 cm wide and hold nine place settings. In addition, these dishwashers are divided into four categories by manufacturers, depending on their design.

Can be built under
Almost all dishwashers offer the option of removing the upper appliance plate so that the appliance can be pushed under the worktop into the kitchen unit. A device that cannot be built under is referred to as a pure floor-standing device.
A 2 to 3 mm thick decorative plate, which is held by a frame attached to the device, can be inserted into the front of the device. Usually this decorative panel is selected to match the kitchen decor. The panel with the controls remains visible. A dishwasher that can be decorated can be built under.
As with a decorable machine, the control panel remains visible with an integrable machine. The difference is that instead of a thin decorative panel, a normal kitchen front (2 to 3 cm thick) is attached to the front of the appliance. This plate is not held by a frame. An integrable dishwasher can be built under.
Fully integrable
How integrable, only the attached kitchen front covers the entire front of the appliance. The controls are on the top of the appliance door. When the door is closed, no control elements (especially no display) are visible, and the dishwasher cannot be distinguished from the other cabinets in the kitchen.

Well-known manufacturers in the household sector are Bosch , Constructa , Electrolux , Miele , Neff , Siemens , Bauknecht and V-Zug .

Table dishwasher

Table dishwashers are small devices that can be placed free-standing on furniture or integrated into cupboard furniture. They hold 6–8 place settings. The table dishwashers are designed for a household of 1–2 people.

Industrial or commercial dishwashers

Washing tub of a gastronomic hood type dishwasher (with and without sieves)

Dishwashers used in trade or industry differ from those used in the household mainly in that they work faster so that the items to be washed can soon be used again and not so many dishes have to be kept in stock.

In the case of smaller units, the dishes to be cleaned are sorted into a standardized basket or rack , possibly temporarily stored, (manually) pre-rinsed, rinsed, dried (or left to dry) and cleared out again. Larger machines often use a conveyor belt for the purpose of transport , which feeds the dishes to the individual processing stages. Usually different devices are used for crockery and cutlery and also for glasses ("glass washers"). In the case of machines used commercially, it is usually worthwhile to use more complex water treatment systems that allow the same rinsing water to be reused several times for many rinsing cycles. In addition, cleaning is carried out with stronger detergents and at a higher temperature (cleaning cycle 65–85 ° C; rinse cycle 85–96 ° C, depending on the model). The rinsing water is only partially replaced, namely the water flowing through the heating boiler for final rinsing is then used for the next cleaning process of the next batch . The amount of three to five liters that flow in this way is pumped out beforehand.

A distinction is also made between the type of dosing: there are automatic dosing devices (mostly with liquid cleaning media) and manual ones (where you still have to fill in the powder). Since the water is reused over and over again, it is recommended that the often heavily soiled dishes and glasses be washed separately.

Front door dishwashers or glasswashers
The smallest commercial dishwashers are available in this design - which are often used as substructure machines in cramped spaces. Special dishwashing machines (e.g. pot washers or machines for cleaning gastro-norm containers) are often offered in this design.
Hood dishwashers or glasswashers
In contrast to the front door machine, with this design the entire housing of the wash cabinet can be lifted upwards, so this design makes the items to be washed accessible from all sides. With this technology, it is also possible to slide the wash baskets or racks into and out of the machine using a rail system. It is not necessary to stoop to fill it.
Belt type dishwashers
In the case of large quantities of crockery (such as canteens or company canteens ), it is worthwhile to have a belt that runs continuously through the dishwasher and that also has holding elements for the individual crockery items. Since the washing process runs continuously, this only makes sense if there are neither large gaps nor fluctuations in the amount of dishes in the dish supply. In the meantime, however, there are models that stop automatically if no dishes are placed on the front surface (the surface in front of the machine to line up the dishes) (the light barrier reacts to contact and then activates the machine; if there is no contact, the machine does not start. At the end there is also a light barrier that registers whether the dishes have arrived there). A major disadvantage is that improperly fitting the belt by guests can damage the dishes.
Through-basket machines
Similar to belt type dishwashers, purchasing a rack-type dishwasher is only worthwhile if you have a large number of dishes. Here the baskets are filled beforehand, and when they are full, they are placed on the front surface (see above) and move through the machine on a conveyor belt. Modern machines have color coding that reads off which program (conveyor speed / temperature) should run. This system also uses the light barrier technology explained above.

One advantage of the catering equipment is the extremely short rinsing time and the pre-rinsing for coarse dirt with already used water. The disadvantage of the devices is that they constantly consume electricity even when not in use because they have to keep the water at around 60 to 70 ° C. Furthermore, they need a lead time of 10 to 30 minutes before the first use.

Average rack or belt type dishwashers create 100 to 200 baskets, which corresponds to 1000 to 2000 plates per hour.

Average hood type dishwashers could theoretically clean 60 baskets per hour, but in practice only manage 45–50 baskets per hour (1 minute with the shortest program). Average front door dishwashers only manage around 30 to 40 baskets per hour (also 1 minute). This deviation is due to the set-up times (sorting dishes, etc.).

Dishwashers in the medical field

For cleaning dishes in the medical-technical sector specific to cleaning and disinfection equipment and bedpan washers and laboratory washers (for the analyzes pure reprocessing of laboratory glassware used).

Connection of the dishwasher to the hot water pipe

Connecting a dishwasher to an external hot water system can save energy. Due to the mostly small amount of water to be heated, this is usually only worthwhile

  • if the hot water is supplied via a solar system, or
  • An existing circulation line ensures that warm water is immediately available at the connection when the dishwasher is in operation, or
  • the water heater is right next to the dishwasher and is connected by the shortest route so that hardly any warm water remains in the pipe.

The program is usually idle while the water in the device is heated. If a dishwasher is connected to an external hot water supply, the running time of the programs can be reduced by 10–30 minutes. The shortened soaking time may have an impact on the cleaning performance.

In addition, external water heating has the advantage that hot water above approx. 55 ° C has a lower lime content, since the lime has already precipitated during the heating process.

If the temperature of the incoming hot water is more than 60 ° C, there is a possibility that plastic and rubber parts may deform in the machine.

Device with connections for hot and cold water

Energy consumption can usually be reduced if a dishwasher has separate connections for hot and cold water and both connections are used. However, this does not apply

  • if the hot water is heated with electricity. In this case, greater losses occur when the device is heated outside than with internal heating.
  • if more than two liters of cold water come out of the hot water pipe before hot water reaches the device. If the amount of water required by the device comes out of the pipe mainly cold, the water must be electrically heated in the device as usual. Then there are even additional energy losses due to the externally heated water, which is now in the hot water pipes leading to the machine and cools down unused.

Device with cold water connection

As a rule, it is also possible to connect a dishwasher without a second connection, which is provided for the supply of hot water, to the domestic hot water line instead of to the cold water line. Energy consumption and costs can be reduced or increased depending on the system for heating water and the amount of flushing water. If the device manufacturer does not allow the connection to the hot water, the guarantee claim may expire.

Whether the connection to the hot water network leads to energy savings must be decided on a case-by-case basis.

The possible savings in the case of hot water generation with gas or oil were calculated to be 30 to 60 euros per year if the machine is switched on five times a week.

Against this:

  • The water is usually only heated electrically in the main wash cycle, the subsequent pre-rinse, intermediate rinse and the regeneration process are usually carried out cold. If the machine only has hot water available, this can result in increased energy consumption.
  • Enzymes for dissolving starch and protein residues , as in many machine dishwashing detergents are included, are only effective at low water temperatures.

The connection to the hot water pipe is often only worthwhile if the water is heated by a solar thermal system.

Household dishwasher with heat pump

Since 2014 household dishwashers have been available on the market that are equipped with a heat pump to reduce the consumption of electrical energy.

Schematic diagram of a dishwasher with a heat pump, integration of the evaporator in a latent heat store

One possibility for integrating a heat pump is to embed the evaporator (cold side) in a latent heat storage device that is filled with clear water. The advantage of using a latent heat storage device is a high storage density, which leads to a compact component. In this heat accumulator, the heat flow from the water / ice mixture is transferred to the refrigerant, which then evaporates. The water, in turn, first cools down and partially solidifies along the evaporator pipe when further energy is extracted. The enthalpy of solidification is released from water to ice, which is used to evaporate the refrigerant. The latent heat accumulator cannot freeze through because the amount of heat withdrawn is limited by the control of the household appliance. After completion of the dishwashing program, the latent heat accumulator slowly regenerates itself through the ambient air of the installation location (usually the kitchen), i. H. the ice melts and the water warms up again to room temperature. As the regeneration of the latent heat storage and the cooling of the device progress slowly, the resident does not feel any temperature change in the kitchen. The energy balance of the installation room is positive, i.e. This means that the energy for melting the latent heat storage is not withdrawn at the expense of the room heating. Compared to purely electrically heated dishwashers, the net energy input into the installation room is smaller with a dishwasher with a heat pump. In the summer half of the year this can be an advantage, as the kitchen has to be heated up less or less cooling energy has to be generated with a building cooling system. The device is designed in such a way that it can be installed in standard kitchen environments without arranging aggregates (e.g. heat pumps) outside. Like a normal dishwasher, it can be installed in a kitchen with a standard dishwasher niche.

Heat pump unit with latent heat storage of a dishwasher

Instead of embedding the evaporator in a latent heat store, a lamellar air heat exchanger can be used. This heat exchanger is flowed through with warm kitchen air, which is conveyed with the help of a fan. A heat flow is transferred from the kitchen air to the refrigerant via the fins , which evaporates in the pipes. In return, the warm kitchen air is significantly cooled and fed back into the kitchen. The evaporated refrigerant is then compressed with the aid of the compressor. In the condenser of the heat pump, a heat flow is transferred from the condensing refrigerant to the process water, which is then warmed up. Compared to the previously described concept with latent heat storage, this system has the advantage that so-called continuous operation can be ensured, i.e. H. the process water of a directly following wash program can also be heated with the heat pump. This eliminates the need to thaw the latent heat storage device, which takes a certain amount of time. The disadvantages of this system are the marked cooling of the kitchen air, which the resident can feel due to the large temperature difference, and the additional energy required to drive the fan. Despite the noticeable cooling of the kitchen air, the energy balance of the kitchen is positive. In other words, when the dishwasher and the dishes cool down, more energy is supplied to the kitchen air than is withdrawn during the washing program by the cooling in the evaporator.

Schematic diagram of a dishwasher with a heat pump, use of a lamellar air heat exchanger for the evaporator instead of a latent heat store

The benefit for both heat pump concepts is the heat flow in the condenser, which heats up the process water - the expense opposing the benefit is the electrical power of the compressor and the spray pump. With the concept with lamellar air heat exchanger, additional electrical power is required for the fan, which transports the kitchen air through the heat exchanger.

A dishwasher with heat pump and latent heat storage technology for use in private households was launched for the first time in April 2014. The annual electrical energy requirement of a dishwasher with a heat pump, determined in accordance with the EN 50242 standard , is 137 kWh. The most efficient dishwasher without a heat pump but with drying by opening the door has an annual energy consumption of 196 kWh. Standard dishwashers, on the other hand, have an annual energy consumption of around 260 kWh. Thus, the need for electrical energy can be reduced by at least 30% by using a dishwasher with a heat pump (as of 2015).

Compared to the electrical resistance heating of a conventional dishwasher, the integrated heat pump requires some additional components. Therefore, in the context of a holistic view, the question of the so-called gray energy , which is necessary for the manufacture of the device, arises . In a model calculation, after a service life of around 1200 cycles, which corresponds to around 3 years with daily use, the point is reached at which the expenditure in the use of materials is balanced. This consideration is based on a cold water connection of the dishwasher.

Energy and resource consumption

The energy label for dishwashers indicates the electricity and water consumption for an assumed 280 wash cycles per year. The heating of the tub, dishes and water makes up the main part of the energy requirement. Machines with less than 44 dB ( decibels ) are considered quiet. The energy consumption label must show: manufacturer and type designation, energy efficiency class, annual energy consumption in kWh, water consumption in liters per year, classification of the drying effect, number of place settings with standard load and the noise emission in dB (A)

According to a study by the Freiburg Öko-Institut (funded by the German Federal Ministry of Education and Research ), dishwashers account for almost 3% of the total electricity demand in private households, 1.4% of the primary energy consumption and 1.1% of the global warming potential of private households (with an average Electricity consumption of 215 kWh per year and device). Added to this is the consumption of an average of around 3 m³ of water and around 4.8 kg of cleaning agent per year.

A study financed by four household appliance and detergent manufacturers comes to the conclusion that program temperatures that are too often selected in Germany are too high and that energy is wasted, and that the appliances are often only half full.

Between 1978 and 1994, the average electricity consumption of the dishwashers sold in Germany fell by 47%.

Modern dishwashers in efficiency class A +++ consume 237 kWh of electricity for 280 wash cycles (as of 09/2012), older machines often consume 365 kWh. By drying with the help of zeolites , the power consumption can be reduced to 232 kWh. Dishwashers with an integrated heat pump have an annual energy consumption of 137 kWh.

Modern devices use 40% less water than 10 year old models.

The mechanical processing of the dishes when washing by hand (wiping, rubbing, scratching) must be compensated for by the chemical effect of hot lye and enzymes when washing with a machine . It is therefore necessary to use more chemicals.

Detergents pressed into tablets (so-called "tabs") are also offered as combination products that are intended to replace detergent, rinse aid and regeneration salt in some cases. One product is offered as an “11-in-1 dishwashing detergent powder”, which acts as a cleaner, rinse aid, glass protection, softener, stainless steel gloss agent, cleaning enhancer, low-temperature surfactant, quick dryer, odor neutralizer, degreaser and silver protection. Some of the ingredients initially washed in (e.g. the temperature-sensitive enzymes) or use (e.g. the cleaning surfactants) only in the main wash cycle, others only in the following wash cycle (e.g. all stain inhibitors, these are unnecessary in the main wash cycle) and others in both rinses (e.g. the softener ). After the main rinse, however, the wash water and all the dissolved chemicals are pumped out, leaving only a residue in the pump sump, the ingredients of which are carried over to the next rinse as a “carry-over effect” and (must) be diluted. So that the chemicals that are only to take effect in the next wash cycle (for example rinse aid and softener in the above-mentioned “11-in-1 dishwashing detergent powder”) are also present in the required concentration in this next wash cycle, they must be in the The tab used (or the required amount of powder) are heavily overdosed so that their concentration in the pump sump is still sufficient after the subsequent dilution. Most of the highly concentrated solution of these substances is already pumped out after the first wash. These chemicals are therefore ineffective for the washing process and pollute the environment.

Other ingredients are also sometimes not required (e.g. softeners for water that has already been softened) or poorly degradable in sewage treatment plants. They accumulate in the receiving waters and have unfavorable effects on the water (see main article machine dishwashing detergent ).

According to a study by the Lower Austrian Chamber of Labor (which, among other things, represents consumer interests in Austria ), many household chemicals are used unnecessarily in dishwashers. This often applies to rinse aid, fragrance rinse aid and machine care products.

Most machines cannot dose the amount of detergent ingredients according to the actual need and the amount added is often difficult or impossible to control manually. The composition of the ingredients in a detergent mixture must therefore always be based on the maximum requirement (full machine, dried-on food residues, high fat content, high water hardness) in order to be effective in every case. Individual ingredients are not required in every case or only in a lower concentration and are then definitely overdosed. If only porcelain is washed, for example, there is no need for “stainless steel protection”; with automatic water softening, no softener is required. If, for example, the automatic water softener could be switched off (because the majority of cleaners contain water softeners), salt loads in the waste water disposal systems could be saved.

In order to achieve an optimal dosage of the cleaning agent and to keep the environmental impact low, dishwashing powder, rinse aid and softener salt should be added separately and individually dosed instead of Multitabs. The tabs are always dosed for maximum contamination of the dishes in order to always get a good result. Powder, on the other hand, can be individually adapted to the degree of soiling and the amount of load. The cleaning process can be optimized by adding salt and rinse aid to the dishwasher's cleaning process in a timed manner and controlled by sensors. This is the only way to adapt to the short program or full program and the best time to wash in the respective components. The time-optimized feed reduces the amount of chemicals required.



  • Rudolf Huttary: Successfully diagnosing and repairing household appliances yourself . Instructions for repairing basic electronic circuits, power supplies, audio devices, televisions. Franz, Poing 2002, ISBN 3-7723-5100-X .

Web links

Commons : Dishwashers  - Collection of Images
Wiktionary: Dishwasher  - explanations of meanings, word origins, synonyms, translations

Individual evidence

  1. Duden online
  2. DESTATIS, equipment from households with electric budgetary and other devices - Germany , Accessed on December 26, 2017th
  3. History of Dishwashers ( Memento from May 2, 2012 in the Internet Archive )
  4. Josephine Cochran's dishwasher , on
  5. Jonathan Chan: How One Woman Revolutionized the Modern Kitchen. In: March 13, 2014, accessed April 29, 2019 .
  6. Dishwasher .
  7. Roland Rieger: How the multifunctional tabs in the dishwasher work ( Memento from April 26, 2014 in the Internet Archive ) (PDF file), at
  8. Lens care. Retrieved November 21, 2019 . , on from the Swiss Brewery Association
  9. Petra Berkholz, Rainer Stamminger, Gabi Wnuk, Jeremy Owens, Simone Bernarde: Manual dishwashing habits: an empirical analysis of UK consumers. In: International Journal of Consumer Studies. 34, 2010, p. 235, doi : 10.1111 / j.1470-6431.2009.00840.x .
  10. Petra Berkholz, Rainer Stamminger, Gabi Wnuk, Jeremy Owens, Simone Bernarde: Manual dishwashing habits: an empirical analysis of UK consumers. (PDF) Accessed on January 6, 2014 : "The authors would like to thank Reckitt Benckiser Ltd and BSH Home Appliances Ltd for supporting this research"
  11. Ina Rüdenauer: Dishwashers as EcoTopTen products, product sustainability analysis (PROSA) of dishwashers and derivation of criteria for the EcoTopTen consumer information campaign , Öko-Institut, Freiburg, 2006, with the collaboration of Elisa Severini, (PDF file; 979 kB)
  12. a b Consumers use their dishwashers too inefficiently Press release from the University of Bonn on a study carried out there (author: Stamminger, Richter et al.) On the use of dishwashers, University of Bonn dated February 24, 2011, accessed on April 24, 2012.
  13. Association of Energy Consumers : Use the dishwasher's economy programs. .
  14. Which washing programs are there? In: Budget consciously. Retrieved on July 29, 2020 (German).
  15. Description of how the automatic program of a dishwasher works. Retrieved August 24, 2020 .
  16. In: test , edition 6/2013; quoted from: Short program users pay extra . t-online, May 28, 2013, accessed on March 18, 2018.
  17. Marco Jankowski: Broken dishwasher - what to do? ( Memento from September 1, 2012 in the Internet Archive ), synopsis of the broadcast from July 2, 2012, 8:15 pm at
  18. Operating instructions for a dishwasher ( Memento from April 26, 2014 in the Internet Archive ) (PDF; 2.1 MB).
  19. a b Commercial dishwashing & metal wash ware , publisher: Arbeitsgemeinschaft Gewerbliches Dishwasher, 2007, PDF file .
  20. a b c Correct washing , instructions from a manufacturer of dishwasher detergents , PDF file .
  21. a b c machine dishwashing detergent, cleanly cleaned .
  22. Stiftung Warentest: Dishwasher Tabs: 2: 0 for Somat , 1997.
  23. Glass expert Professor Reinhard Conradt from the Technical University in Aachen in conversation with Frank Eckhardt in The Small Inquiry: Glass Corrosion - Why does some glass go blind in the dishwasher? , at Leonardo - Wissenschaft und mehr, transmission date: May 14, 2009, PDF file at
  24. Stiftung Warentest : Glasses and cutlery in the dishwasher ( test 02/2004) accessed on February 4, 2013.
  25. a b Dishwasher guide , at
  26. Instructions for use from a manufacturer .
  27. Benziotriazol , accessed on January 3, 2012 found.
  28. a b Dishwasher to hot water? , Association of Energy Consumers, May 2006
  29. Excel data sheet Dishwasher ans Warmwasser ED , In: , 2004. The Federation of Energy Consumers offers a table to weigh up the advantages and disadvantages.
  30. Dishwasher to hot water? , In: May 2006. The Association of Energy Consumers calculates savings of 100 to 200 kWh per year. With an electricity price of 30 cents, you save € 30 to € 60.
  31. Jürg Werner, Ernst Dober: Dishwasher with heat pump . In: patent specification . EP 2 446 796 B1, 2009.
  32. ^ Albert Johann Loichinger, Ingo Gau, Ernst Dober, Stefan Flück: Dishwashers with latent heat storage . In: patent specification . EP 2 322 072 B1, 2011.
  33. Andre Bertram, Tobias Dahms, Martin Kornberger, Michael Reilmann: Dishwasher and method for operating a dishwasher . In: patent specification . EP 2 682 037 A2, 2014.
  34. ↑ A world first - dishwasher with heat pump technology. Retrieved March 10, 2015 .
  35. Dishwasher GA60KVSW. (PDF) (No longer available online.) Archived from the original on April 2, 2015 ; accessed on March 10, 2015 . 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. @1@ 2Template: Webachiv / IABot /
  36. Integrated XXL dishwasher with delay start and remaining time for maximum convenience at an affordable entry-level price. (No longer available online.) Formerly in the original ; Retrieved June 20, 2014 .  ( Page no longer available , search in web archivesInfo: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice.@1@ 2Template: Dead Link /  
  37. a b Comparison of built-in dishwashers. (No longer available online.) Archived from the original on February 10, 2015 ; accessed on March 10, 2015 . 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. @1@ 2Template: Webachiv / IABot /
  38. ^ Dishwashers , North Rhine-Westphalia consumer center
  39. The EU energy efficiency label, save energy and costs when purchasing a device! Advice and tips for buying and using, brochure from the Austrian Chamber of Commerce and the Austrian Energy Agency
  40. Ina Rüdenauer: Dishwashers as EcoTopTen products, product sustainability analysis (PROSA) of dishwashers and derivation of criteria for the EcoTopTen consumer information campaign , Öko-Institut, Freiburg, 2006, with the collaboration of Elisa Severini, (PDF file; 979 kB) .
  41. Ulrich Oltersdorf, Thomas Preuß: Households on the Threshold of the Next Millennium, Aspects of Household Research - Yesterday, Today, Tomorrow , Campus-Verlag, Frankfurt / Main, 1996, ISBN 3-593-35543-4 , page 229 ( limited preview in Google Book Search).
  42. Energy consumption of dishwashers , Öko-Institut eV Energy consumption of dishwashers ( Memento from October 24, 2013 in the Internet Archive ) (PDF file), on
  43. New dishwashers save electricity with innovative technology: The mineral zeolite dries cups and plates very energy-efficiently , eco @ work magazine, April 2010, ISSN  1863-2017 , Öko-Institut eV, PDF file ( Memento of the original from August 16, 2010 in 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. . @1@ 2Template: Webachiv / IABot /
  44. ↑ Saving water: Dishwashers - Are dishwashers really as economical as the manufacturers claim? .
  45. Rossmann / Domol 11in1 Dish Cleaner Tabs 2 tests , on
  46. ↑ Dosing correctly - washing dishes with measure and aim , last accessed in June 2013.