Where to Use Undercounter, Door-Type, and Conveyor Commercial Dishwashers

Commercial dishwashers are designed for very different restaurant environments. The three most common types—undercounter, door-type, and conveyor dishwashers—differ mainly in capacity, speed, size, power requirements, and workflow.

Understanding these differences is the first step toward choosing the right commercial dishwasher for your restaurant.

1. The Three Main Types of Commercial Dishwashers

These are representative manufacturer ranges, not universal limits. Actual capacity depends on the model, rack configuration, cycle time, and operating conditions. Hobart's commercial dishroom guidance places undercounter machines at roughly 13–48 racks/hour, door-type machines at roughly 36–60 racks/hour for standard configurations, and rack conveyors at approximately 202–342 racks/hour. Some specialized door-type configurations can reach higher capacities.

Undercounter: Best when kitchen space is limited but commercial dishwashing performance is still required.

Door-Type: Best when the restaurant has a dedicated dishwashing area and needs more capacity during busy periods.

Conveyor: Best when hundreds of racks need to be processed continuously.

2. How Much Dishwashing Capacity Does Your Restaurant Need?

The most useful number to understand is racks per hour (RPH).

A rack is the standard unit used to organize dishes, glasses, and other ware for washing.

For example, if your restaurant needs to process 120 racks during a 3-hour dinner rush:

120 ÷ 3 = 40 racks/hour

That means your dishwasher system needs to average at least 40 racks/hour during that peak period.

This is why restaurant owners should look at peak dishwashing demand, not simply the number of seats.

A 40-seat restaurant with a busy dinner service may have very different dishwashing requirements from a 100-seat restaurant with slower table turnover.

As a general manufacturer guideline, Hobart associates undercounter machines with operations serving up to about 50 meals/hour, door-type machines with approximately 50–100 people per meal, and rack conveyors with approximately 250–1,500 meals/hour. These figures are guidelines rather than universal restaurant-sizing standards.

A Simple Rule

Required RPH = Peak racks to wash ÷ Peak washing hours

For example:

• 90 racks ÷ 3 hours = 30 RPH

• 120 racks ÷ 3 hours = 40 RPH

• 180 racks ÷ 3 hours = 60 RPH

• 300 racks ÷ 3 hours = 100 RPH

Once you know your required RPH, the choice between dishwasher types becomes much easier.

3. Speed, Cycle Time, and Temperature

Dishwasher speed is not determined by one specification.

Three numbers are particularly important:

Rack capacity + cycle time + wash temperature

Cycle Time

Cycle time tells you how long one complete washing cycle takes.

These are theoretical cycle frequencies. Actual racks/hour can be lower because employees still need to load and unload racks.

For example, an undercounter machine with 85-second, 115-second, and 175-second cycles provides different operating options depending on the workload and cleaning requirements.

Temperature

Commercial high-temperature dishwashers commonly operate with a main wash temperature around 140–160°F and a final rinse around 180°F or higher, depending on the machine and applicable requirements.

The main wash and final rinse perform different functions. Cleaning performance also depends on wash pressure, spray coverage, detergent, wash time, rack loading, and water conditions.

NSF/ANSI 3 covers commercial warewashing equipment and establishes requirements for design, construction, materials, and performance. Exact sanitizing requirements depend on the equipment type and configuration.

4. Power, Space, and Installation

Commercial dishwashers generally require more electrical power than residential machines because they must heat water quickly and repeatedly during commercial operation.

However, there is no single standard power rating for each dishwasher type.

Power requirements depend on:

• Voltage

• Phase

• Amperage

• Tank heater

• Booster heater

• Wash pump

• Rinse system

• Machine capacity

For example, many commercial machines are available in 208–240V configurations, but the actual electrical requirements vary by model.

The installation should always be checked against the machine's specification sheet and the restaurant's available electrical service.

Space Can Be a Deciding Factor

A conveyor dishwasher may offer several hundred racks per hour of capacity, but it also requires significantly more space.

An undercounter machine may provide substantially less throughput, but its compact footprint can make it much easier to integrate into a small kitchen.

Therefore:

More capacity is not always better if your kitchen cannot efficiently use it.

5. Which Dishwasher Type Is Right for Your Restaurant?

The easiest way to choose is to compare dishwashing volume, available space, and peak service requirements.

Quick Decision Guide

Choose an Undercounter Dishwasher if:

• Kitchen space is limited

• Peak demand is moderate

• You need approximately 20–40+ racks/hour

• You want a compact commercial dishwasher

• You do not need continuous rack washing

Choose a Door-Type Dishwasher if:

• Your restaurant has a dedicated dishwashing area

• Peak demand is higher

• You need approximately 40–80 racks/hour

• You want more capacity without moving to a conveyor system

Choose a Conveyor Dishwasher if:

• You need to process hundreds of racks per hour

• Dishwashing is continuous during service

• Your kitchen has enough space for a dedicated dishroom

• High throughput is more important than compact installation

The Bottom Line

There is no single "best" commercial dishwasher.

The right choice depends on four numbers:

Peak Racks/Hour + Cycle Time + Temperature + Available Electrical/Physical Capacity

If your restaurant needs 40 racks/hour, a machine capable of around 40 racks/hour may be sufficient. If you need 200+ racks/hour, a conveyor system becomes much more appropriate.

The goal is not to buy the biggest commercial dishwasher.

The goal is to match the dishwasher to your restaurant's actual workload and kitchen.