How To Size A Commercial Dishwasher

Buying the right sized dishwasher is critical to your restaurant’s ability to keep up with demand. Too little capacity means you fall behind at critical moments – no one like to get a pint glass still sweating condensation and heat because it just came off the last rack. Too much capacity means you spent too much money up front that could have gone towards another part of your business. Meanwhile, the dishwasher puts an extra burden on monthly energy expense.

The most common unit used for measuring dishwashing capacity is racks per hour.

Most dishwasher manufacturers list the number of dish racks per hour a particular model can process. Be sure to get this information for any commercial dishwasher you’re considering.

In general, racks can hold 18 dishes or 36 glasses. A flatware rack’s capacity varies widely, depending on how much flatware gets piled into the rack, but as a general rule the average is 25 – 50 pieces per rack. Calculate how many racks you generate per hour and then weigh that number against the number of racks the dishwasher you’re looking at can handle.

To calculate how many racks you generate per hour, first count up the dishes at each place setting: bread plate, appetizer plate, entrée plate, water glass, flatware, etc. Next figure how many place settings you go through in an hour on average and at peak volume times by looking at the number of meals you sold.

Be sure to account for peak volume as opposed to average volume. The trick is to buy enough capacity to keep up with peak volume (even if dishes pile up a little) while not buying so much capacity that your staff is running half-full racks every weeknight. The larger the unit, the more energy and water it consumes, and if dishes are processed too quickly then racks tend to go through half empty, resulting in inefficient operation. Make sure you take the time to accurately calculate dish load and select the right sized dishwasher.

Finally, take future growth into account. A commercial dishwasher should have a 5 – 10 year life, and in that time your business should be growing. If you purchase some extra capacity at the beginning, you’ll save yourself some serious cash later on. Also don’t forget about seasonal trends! Certain times of year can also be much busier. Make sure the dishwasher you buy can handle these peak dish load times.