Why is a commercial dishwasher not cleaning properly?

1. Are the wash and rinse arms blocked?

Arms and nozzles get blocked by food debris, lemon pips, toothpicks or scale. A blocked nozzle leaves part of the rack completely unwashed.

Remove the arms as the manufacturer describes, clean the nozzles, and after refitting them turn them by hand to check that they rotate freely.

2. Are the filters and the tank water clean?

The tank water is reused for every wash and gets dirty during the day. Full filters and dirty water carry grease and debris back onto the dishes you are washing.

Empty the filters during the day as well, change the tank water as it gets dirty, and at the end of the day drain and clean the tank completely.

3. Are the dishes loaded correctly?

• Scrape food residue off before loading; soak dried-on food in advance.
• Do not overload the rack; plates should not cover each other.
• Place glasses and containers upside down in the right rack.
• Put cutlery upright and spread out in the basket.

4. Are the detergent and rinse aid reaching the machine?

The container may be empty, the suction hose may not reach the bottom of the container, or there may be air in the hose. Even if the dosing pump is running, the product will not reach the machine if the hose is kinked or blocked.

Use only products made for commercial machines and suitable for automatic dosing. Household detergent foams; the foam reduces the pump’s power and spoils the wash.

5. Are the temperatures high enough?

In commercial dishwashers the wash water is usually around 55–65 °C and the final rinse water around 80–85 °C; the correct values are in the machine’s manual. If the wash water is too cool, grease does not dissolve; if the rinse water is too cool, dishes are neither hygienic nor do they dry quickly.

If the display shows a low temperature or the machine keeps waiting to heat up, the heating element, thermostat or contactor needs to be checked. That is a job for a technical service.

6. Is there limescale?

In hard water, scale coats the heating elements and slows heating, and narrows the rinse nozzles. A white film and dullness on glasses is also often limescale.

If there is a softener, check its salt and setting. If scale has built up, descaling of the heating elements and boiler is done at scheduled maintenance.

7. Are the water pressure and water supply sufficient?

Rinsing is done either at a certain water pressure or with a rinse pump. If mains pressure is low or the inlet filter is blocked, the rinse is weak and detergent residue leaves marks on the dishes.

8. Is the pump working properly?

When the wash pump weakens, the arms turn slowly and the water pressure drops. Foreign objects that get into the pump (broken glass, labels, toothpicks) can damage the impeller. An unusual noise or a water leak from the pump needs a service visit.

What do the marks tell you?

• Greasy film: low wash temperature, too little detergent or dirty tank water.
• White spots and dullness: limescale, hard water or an incorrect rinse-aid setting.
• Drip marks and streaks: too little rinse aid or a low rinse temperature.
• Food particles: blocked arms, a full filter or an overloaded rack.
• Foam: household detergent, or detergent residue carried into the machine on the dishes.

When should you call a technical service?

• If the problem continues even though the arms, filters and tank water are clean.
• If the machine does not heat or keeps waiting to heat up.
• If it does not fill, does not drain or leaks water.
• If the pump is noisy or the circuit breaker trips.

During a service visit we measure the wash and rinse temperatures and check the dosing pumps and heating elements. Every job ends with a written service report.