Dish Machine Basics

This energy efficient dishwasher is outfitted with an optional blower dryer and uses less space than many comparable models.

Dish machines are an essential part of every kitchen and a capital investment that can't be avoided. When it's time to buy a new one or replace an aging one with out-of-control maintenance costs, brush up on the basics and then locate expert help to identify costs, specifications and paybacks. Here are some tips to get you started…

Understand the process

Sure — racks of soiled dishes are fed into one side of a warewashing machine and come out clean on the other. But regardless of machine size, the cleaning process typically has five steps. Understanding these helps you understand how dishwashers operate and when and why different options are available.

First, dishes need to go through a prewash stage where large food waste particles are scraped or rinsed away. Often, this is done by hand, though larger units can be outfitted with automated pre-wash modules. Since code requirements increasingly restrict the use of disposers to handle such waste, food and some kinds of paper waste are sometimes transferred to a trough that uses a recycled stream of water to carry it to a pulper, where it is ground up.

In the second stage, dishes enter the machine on racks and go through a hot wash cycle. Typically, a pressurized spray of detergent and water heated to 140°-160°F softens and removes most of the remaining soil. The spray is applied by swirling jets that ensure all surfaces receive attention.

In a third, power-rinse stage, hot rinse water (typically 160°F or above) is again forcibly sprayed on the items being cleaned.

The fourth stage is a final, sterilizing rinse, this time with water usually brought to 180°F with a booster heater (in “lo-temp” machines, sanitizing chemicals replace the heat).

In the final stage, dishes are dried, usually by air (facilitated by the high temperature of the last rinse) or sometimes with an additional forced air module added to the machine's end to ensure more complete drying.

Get expert help to ensure equipment is appropriately sized to your needs

Dishwashers are long term capital investments and need to be specified to match the duty cycles, cleaning loads and other requirements of an operation. Undersizing a machine reduces efficiency, generates higher maintenance and creates backups in your kitchen. Oversizing means you'll be paying for unused capacity with capital dollars better spent elsewhere.

For small satellite operations with modest cleaning volume needs, an undercounter dish machine may be perfectly suitable. Door-type machines offer sigificantly greater throughput with a fairly small footprint in a kitchen.

Most larger operations need a conveyor-type machine, but the number and size of their tanks need to be sized carefully. “Value engineering” brings higher operating costs if tanks are undersized for the real load factors you experience. For the highest demand locations, flight-type machines are the way to go. These operate as continuous conveyors without the need for racks and are designed to be in continuous use for significant periods or shifts.

When all of the modules and options are considered, dish machines can be specified in a nearly infinite permutations. A qualified consultant can help you size and specify.

Consider all of the options

Pot washers, add-on air dryers, pulpers, automated pre-wash modules and other options all have a place in the right circumstances.

Ask for customer references in operations similar to yours that have installed and used the kinds of equipment you are considering. Contact them yourself, and don't settle for just one or two. You can learn a lot from other folks' experience, as well as the pros and cons of certain features that may really matter in your operation.

Energy and water conservation have become game-changers. Improvements in water recirculation, spray head and valve design, heat recovery and pump and motor specifications can generate very significant paybacks compared with the cost such enhancements add to a basic unit. Make sure you hire a consultant who can advise your about these areas, and make it clear that energy and water savings are high on your agenda.

Paybacks are faster in operations that have heavy duty cycles — some casinos have experienced ROIs in less than year by investing in new machines, but these often run dishwashers for two shifts or more. Onsite operations can more realisitically expect returns in 3-4 years, but that can still be an excellent investment given the life expectancy of this kind of equipment. Again, a capable consultant can help you evaluate which improvements will pay off and how long it will take.