How Dishwashers Work

Dishwasher Operating Principles

Baikal Services, Baikal Plumbing, Baikal Heating, Baikal Electrical, Baikal RooterEven though there is a wide variety of many different dishwasher models, they all operate on similar principles. There are five basic principles as to how dishwashers operate: filling, washing, draining, rinsing, and drying. In most cases, the filling cycle will begin with removing the water from the dishwasher. Some of the water remains in the housing. It prevents the seals from drying out and cracking when the dishwasher is not in use. Most dishwashers have a timed filled cycle that will allow no more than two gallons of water to enter during the operation. The home water supply line connects to the water inlet valve on a dishwasher. When you select a wash cycle, the control sends 120 volts of alternated current to the inlet valve solenoid, opens the lid, and allows the proper amount of water into the tub. In most dishwasher models, the voltage sent by the control will keep the valve open between 90 and 120 seconds. If the control fails and does not shut off energy to the valve, a float will fluctuate a switch that shuts off the water. Keep in mind that the purpose of the float is to prevent over filling. Having the correct amount of water is vital to the dishwasher’s performance. If the tub does not receive a proper amount of water, the dishware will not wash properly. In most cases, under-filling is caused by a restricted water inlet valve. To determine this, fill the machine with one to two quarts of water and run the cycle. If washing performance did not get better, then the valve is probably blocked and should be changed. Do not try to clean out and use the old valve. It is not recommended to use the old part due to the risk of part failure after repair.

Once the right amount of water enters the tub, the washing stage begins. The three factors that affect the wash cycle are – water circulation, detergent, and water temperature. The control sends voltage to a circulation motor to circulate the water inside the dishwasher. The motor turns a pump that uses an impeller to push the water through the wash arms. The water is getting out of the holes and directs the arms. If the wash arms are not rotating or you experience pore wash performance the cause could be a worn or damaged impeller. As the food debris is cleaned from the dishware, it collects in the sump which filters and retains the larger particles. This filter prevents the food particles from being circulated through the wash arms. Over time, some particles may still reach the wash arms, clogged the holes, and reduce wash performance. So you may need to clean out the holes periodically. Also, be aware that it is normal for the arms to feel a little loose when not in operation. A wax motor or solenoid causes the dispenser to open, releasing detergent and mixing with the water. Sense dishwasher detergent does not create suds like other soaps; you should only use a cleanser that is made for dishwasher use. Be aware that too much detergent may not wash away and lives residue on your dishware. BAIKAL SERVICES® recommends following the manufacturer’s instructions. During the wash cycle, the dishwasher may use a heating element in some settings. The control will send voltage to the element periodically to maintain the water temperature between 120 – 160 degrees Fahrenheit. If a problem develops, a high-limit thermostat will turn off the voltage to avoid the damage to the machine. If you think the heating element is not working, you can test for continuity to determine if the continuous electrical path is present.

After the completion of each wash cycle, the dishwasher will drain the dirty water from the tub. The control sends voltage to a drain pump to force water through the drain hose to a disposal or pipe. To ensure proper draining and that the water does not flow back into the tub, make sure that the drain hose that goes above the drain has a loop. If the water does not drain, first check the drain hose for any abstractions. It may be that the drain pump could be defective and need to be replaced.

The dishwasher will go through several rinse cycles which are similar to the wash cycles and may also use the heating element. The final rinse cycle deposits rinse aid from the dispenser instead of detergent. Rinse aid helps to dry the dishware and prevents spots caused by hard water. You should consult the owner’s manual to determine the optimum rinse aid setting for your use. Following the rinse cycles will be a final drain cycle. As stated above, some water will stay in the tub to protect the seals from cracking.

The drying process will begin right after washing and rinsing the dishware and draining the water from the unit. Two things are required to dry dishware efficiently – heat and venting. Some models will use the heating element to heat the air; other models will generate the heat by the final rinse cycle. The hot moist air will either exit through a prominent vent or through a vent in the door, which is open by a wax motor solenoid. Without proper venting, the moisture or water vapor would condense back into the liquid and collect on the dishware.

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