Commercial Dishwasher Maintenance: What to Check, Common Faults and When to Replace Parts
Commercial dishwasher maintenance comes down to three routines: clean the filters and wash arms every day, keep limescale and chemical dosing under control, and inspect wear parts such as pumps, heating components and door gaskets before they fail. Many drops in wash quality can be traced back to one of these areas.
Problems rarely appear overnight. Residue on plates, cloudy glasses, longer cycles or water left in the tank usually build up over weeks. This guide links each symptom to its most likely cause, explains what the key components do and shows how to decide whether a part needs cleaning, adjustment or replacement.
How a Commercial Dishwasher Cleans
Every wash cycle relies on four systems. If one of them underperforms, results suffer even when the rest of the machine is in good condition.
Circulation and drainage: filters keep food soil out of the wash water, the wash pump drives water through the wash arms, and the drain pump removes used water.
Heating: heating elements, the boiler, thermostats and temperature probes keep wash and rinse water at the set temperature.
Water inlet and chemical dosing: solenoid valves and pressure switches control filling, while dosing pumps add detergent and rinse aid.
Sealing and control: the door gasket keeps water and heat inside, and the controller runs each stage of the programme.
Temperature deserves particular attention. Winterhalter points out that grease is only removed effectively above 55 °C. Dishwasher manufacturer Sistema Project Italia gives typical values of 55–65 °C in the wash tank and 80–90 °C for the final rinse. The correct setpoints for your machine are in its manual, so check the display against them regularly.
Commercial Dishwasher Not Cleaning Properly? Troubleshooting by Symptom
Start with the simplest explanations. Blocked filters, empty chemical containers and overloaded racks are quick to check and frequently to blame, so rule them out before suspecting a component.
| Symptom | Likely causes | Check first | Parts that may need replacing |
|---|---|---|---|
| Food residue on plates | Blocked filters or nozzles, low wash temperature, too little detergent, overloaded racks | Clean filters and nozzles, check detergent level and wash temperature, reload racks with more space | Wash pump, heating element, detergent dosing pump |
| Cloudy glasses or white film | Limescale from hard water, incorrect detergent or rinse-aid dosing | Check the water softener and salt, review dosing settings, descale if deposits are visible | Water filter cartridge, dosing pump tubing |
| Streaks, spots or poor drying | Rinse temperature too low, rinse aid empty or incorrectly dosed | Check rinse temperature and rinse-aid level, prime the dosing line | Boiler heating element, thermostat, temperature probe, rinse-aid pump |
| Water left in the tank | Blocked drain filter or drain area, drain pump fault | Clean drain filters and accessible drain areas | Drain pump |
| Slow or incomplete filling | Blocked inlet filter, low supply pressure, faulty solenoid valve | Clean the inlet filter, make sure the water supply is fully open | Solenoid valve, pressure switch |
| Longer cycles or slow heating | Limescale on heating elements, faulty thermostat or probe | Descale, compare the displayed temperature with a measured value | Heating element, thermostat, temperature probe |
| Excessive foam | Unsuitable or overdosed detergent, heavily soiled wash water | Check the detergent type and dosing, drain and refill the tank | Detergent dosing pump |
| Water leaking at the door | Worn or displaced door gasket, debris on the sealing surface | Clean the gasket and sealing surface, check it is seated correctly | Door gasket |
| Programme stops or recurring error codes | Sensor, switch, wiring or control fault | Note the error code and look it up in the manual | Probe, pressure switch, PCB (diagnosis by a technician) |
Error codes differ between manufacturers and models. Always check them against the machine’s documentation before ordering parts.
Key Components: What They Do and Signs of Wear
Before opening any panel, disconnect the machine from the power and water supply and follow the manufacturer’s servicing instructions. Work on electrical, pressurised or hot components should be left to a qualified technician.
Filters, Wash Arms and Nozzles
Tank and pump filters stop food soil from circulating and reaching the pumps. The wash and rinse arms spread water through small nozzles, which block easily with debris or limescale. Sistema Project Italia recommends removing and rinsing the filters, arms and nozzles at the end of every service, and Meiko notes that busy kitchens may need to clean the filters several times a day.
Replace dishwasher filters that are torn, bent or no longer sit correctly, because debris will bypass them. Wash arms that are cracked or warped should also be replaced, as they cannot spray evenly.
Wash Pump and Drain Pump
The wash pump supplies the pressure that removes soil, and the drain pump empties the tank. Weak spray, grinding noises, vibration or water left in the tank are typical signs of wear. Blocked filters cause the same symptoms, however, so clean them first. If the problem remains, have the pump checked before replacing wash and rinse pumps or drain pumps.
Heating Elements, Boiler, Thermostats and Probes
Heating elements in the tank and boiler bring water up to temperature, while thermostats and temperature probes tell the controller when to switch them on and off. Limescale insulates the elements, so heating slows down and cycles take longer.
A machine that cannot reach temperature does not necessarily have a failed element. A faulty thermostat or probe can give the controller a false reading, so check all three together before replacing anything.
Water Inlet: Solenoid Valves, Pressure Switches and Water Filters
Solenoid valves open and close the water supply, and pressure switches tell the controller when the correct water level has been reached. A blocked inlet filter or a sticking valve causes slow filling, while a faulty pressure switch can lead to overfilling, underfilling or interrupted cycles.
Water filters and softeners protect the whole machine from limescale. Replace or regenerate them at the interval the manufacturer specifies, and shorten that interval if your water is hard or the machine runs all day.
Detergent and Rinse-Aid Dosing
Many commercial dishwashers use peristaltic dosing pumps, which move detergent and rinse aid by squeezing flexible tubing with rollers. Over time the tubing hardens, cracks or loses its shape, and dosing becomes inaccurate. Greasy ware, streaks, poor drying, foam or a sudden change in chemical consumption are typical signs.
Check the suction lines and injection points first, then the tubing. Replacing worn tubing may be enough to restore accurate dosing without changing the whole pump. Sistema Project Italia, for example, includes replacing the suction and dosing tubes in its technician service every 5,000 wash cycles. For help choosing dishwasher detergents and rinse aids, see our guide to commercial kitchen cleaning detergents.
Door Gaskets
The door gasket keeps water, steam and heat inside the wash chamber. Wipe it daily so food debris does not stop it from sealing properly. Once a gasket is cracked, hardened or permanently deformed, cleaning will not help and the door gasket should be replaced.
Electronic Controls
The control board (PCB) runs filling, heating, washing, dosing, rinsing and draining. Irregular programmes or recurring error codes can point to a control fault, but the cause is often a probe, switch or loose connection that sends the board incorrect information. A technician should rule these out before a dishwasher PCB is replaced.
Commercial Dishwasher Maintenance Checklist
Use this checklist as a starting point and adapt it to the manufacturer’s instructions, your water hardness and how intensively the machine is used. Recording each task, together with replaced parts and recurring faults, builds a service history that makes gradual deterioration easier to spot.
| Frequency | Task | What to look for |
|---|---|---|
| Daily, end of service | Drain the tank, remove and rinse the tank and pump filters | Torn or displaced filters, heavy soil build-up |
| Daily, end of service | Clean the wash and rinse arms and nozzles | Blocked or damaged nozzles |
| Daily, end of service | Wipe the tank and door gasket, leave the door open to dry | Debris on the seal, odours |
| Daily, before service | Check detergent and rinse-aid levels, and salt if a softener is fitted | Empty containers, unusual consumption |
| Daily, during service | Watch wash results, wash and rinse temperatures, and cycle time | Residue, cloudy glasses, longer cycles |
| Weekly | Inspect the door gasket closely | Cracks, hardening or deformation |
| Weekly | Check suction lines and dosing tubes | Kinks, cracks, air in the lines |
| Monthly | Look for limescale on heating elements, in the tank and on nozzles, and descale if needed | White deposits, slower heating |
| Monthly | Check filling and draining | Slow filling, overfilling, water left in the tank |
| As specified by the manufacturer | Replace water filter cartridges or regenerate the softener | Record the date, shorten the interval in hard-water areas |
| As specified by the manufacturer | Preventive service by a qualified technician | Pumps, heating, dosing tubes, electrical components and controls |
Hard Water and Descaling
Limescale is behind many of the problems in the troubleshooting table. It builds up on heating elements, in the boiler and in the wash arms, and reduces heating performance over time. On the ware itself, it shows up as a white film on glasses and plates. Three measures keep it under control:
Treat the water. Check your water hardness and fit a softener or treatment filter where needed. Sistema Project Italia, for example, recommends an external softener for its machines above 15 °f (French degrees of hardness). Your manufacturer’s limit may differ.
Keep built-in softeners topped up. If your machine has an integrated softener, refill the salt regularly.
Descale on schedule. Use a descaler made for commercial dishwashers and follow the manufacturer’s schedule and dosage. Hobart warns that overusing descaler, detergent or rinse aid can harm the machine in the long term.
If heating is still slow after descaling, check the thermostat and probe, then the heating element itself.
Operating Habits That Affect Wash Results
Some cleaning problems have nothing to do with worn parts. Hobart and Meiko both highlight the same everyday habits:
Scrape or pre-rinse ware before loading. Large food particles block filters and nozzles quickly. A well-maintained pre-rinse unit makes this step faster.
Do not overload racks. Leave space between items so water and chemicals reach every surface, and use the right rack for each type of ware.
Match the programme to the soil level. Heavily soiled ware needs a longer or more intensive cycle.
Use only commercial dishwasher chemicals. Detergents made for domestic dishwashers are not suitable.
Protect stainless steel. Clean the machine with products suitable for stainless steel and never use steel wool.
Train every shift. These steps only work if all staff follow them consistently.
Clean, Repair or Replace?
When wash results decline, work through three steps.
1. Clean and test. Clean the filters and nozzles, descale if needed, prime the dosing system and run a normal cycle. If results return to normal, no part needs replacing.
2. Investigate problems that come back. If a fault returns soon after cleaning, a component is probably wearing. Narrow it down with the troubleshooting table, and rule out sensors, switches and wiring before blaming a pump, heating element or control board.
3. Replace what cannot be restored. Parts that are physically damaged, mechanically worn or electrically faulty need replacing. Typical examples are a cracked door gasket, a leaking solenoid valve, hardened dosing tubing, a noisy or weak pump, and a heating element that still cannot reach temperature after descaling.
Replacing a single worn component can restore normal performance without replacing the machine. Doing it during planned servicing also avoids emergency call-outs and protects connected parts. Where the manufacturer offers service kits that combine related wear parts, they are practical for planned servicing. Individual parts are the better choice once the fault has been clearly identified.
How to Find the Right Replacement Part
Component designs, part numbers and electrical ratings vary between manufacturers and even between models from the same brand. Before ordering a part:
Note the manufacturer, model and serial number from the rating plate.
Find the original part number in the machine’s documentation or on the old part.
Compare connection sizes, voltage and power rating with the replacement.
At Horecatiger you can search by part number or browse spare parts by brand, including Winterhalter, Hobart, Meiko, Comenda and Dihr.
Conclusion
Reliable wash results depend on a short daily cleaning routine, controlled water quality and chemical dosing, and the timely replacement of wear parts. Working from symptom to cause also avoids replacing parts that were never faulty. When a component does need replacing, you will find spare parts for commercial dishwashers at Horecatiger.
Frequently Asked Questions
Why is my commercial dishwasher not cleaning properly?
The most common causes are blocked filters or nozzles, a wash temperature that is too low, incorrect detergent dosing and overloaded racks. Clean the filters and wash arms first and check chemical levels. If results do not improve, check the wash pump, the heating system and the dosing pump.
How often should a commercial dishwasher be cleaned?
At the end of every service day: drain the tank, rinse the filters, clean the wash arms and leave the door open to dry. In busy kitchens, the filters may need cleaning several times a day.
What temperature should a commercial dishwasher be?
Typical manufacturer values are 55–65 °C in the wash tank and 80–90 °C for the final rinse. The exact setpoints depend on the machine, so always follow the manufacturer’s specification.
How often should you descale a commercial dishwasher?
It depends on your water hardness and how much the machine is used, so follow the manufacturer’s descaling schedule. White deposits in the tank, on the nozzles or on glasses, and slower heating, are signs that descaling is due.
Why are my glasses cloudy after washing?
Cloudy glasses are usually caused by limescale from hard water or by incorrect detergent or rinse-aid dosing. Check the water softener and salt level, review the dosing settings and descale the machine if deposits are visible.
Why is my commercial dishwasher not draining?
Food debris in the drain filter or drain area is the most common cause. Clean these first. If water still remains in the tank or the drain pump makes unusual noises, have the pump inspected by a technician.
Can I use domestic detergent in a commercial dishwasher?
No. Manufacturers such as Hobart advise using only chemicals intended for commercial dishwashers and recommended by your chemical supplier.
How do I know if the wash pump needs replacing?
If spray pressure stays weak after the filters and wash arms have been cleaned, or the pump grinds, vibrates or runs noisily, it may be worn. Have it checked by a technician before ordering a replacement.