BY JAMES DULLEY

When it’s time to replace an old — and obsolete — dishwasher, what are the important efficiency features? Is hand washing dishes more efficient?

Using an automatic dishwasher is typically more efficient than hand washing dishes (although if you take your time and are miserly with water usage, hand washing can be more efficient).

No matter which new dishwasher you select, you can be certain it will use less electricity and hot water than your old one. The vast majority of dishwashers made today exceed the Energy Star efficiency standards. Over the life of the new dishwasher, the energy and water savings can pay back your initial cost.

The majority of the cost of using a dishwasher comes from the energy to heat the water. A portion of this energy is used by the home’s primary water heater, the rest by an internal heater. So if a dishwasher consumes less water, less energy is needed. Always compare the overall water-consumption specifications for an average load cycle among the models.

Of course, the most important feature is how well a washer cleans dishes. If it doesn’t clean well, people tend to run it on the heavy cycle or hand rinse the dishes first. Rinsing can use more than 10 extra gallons of water, and if hot water is used, more energy is consumed. With a good dishwasher, a simple hand scraping of dirty dishes should be adequate.

Top-of-the-line dishwashers offer many cycle settings to fine tune the process to the cleaning needs of the specific load. This is a nice feature, but most families can get by with three basic cycles: light, medium and heavy (for pots and pans).

Some dishwashers also sport a two-pump design in the bottom of the tank: one small pump is used for spraying the dishes, and another is used to drain the unit. Many models still use a single reversing pump, which sprays in one rotation and drains in the other. Two smaller pumps require a smaller water reservoir, but the efficiency difference between one- and two-pump models has narrowed considerably. And newer electronic controls offer greater convenience and efficiency.

Newer dishwashers are also much quieter than older ones, accomplished by better motor/pump design and higher levels of insulation — both for noise reduction and for better efficiency. Layers of insulation are placed around the pump assembly and the walls of the cabinet and door. The stainless steel dishwasher I recently installed in my own home is significantly quieter and has shorter cycles.

Automatic dirt sensors measure the turbidity (cloudiness) of the water to determine when the dishes are clean and how long to run the cycles. There are several technologies that accomplish this, and they function pretty well. A filter option strains the water inside the dishwasher to remove food particles. Self-cleaning models use a grinder, but this may increase the noise level. A rinse-hold feature uses only 2 gallons of water to rinse the dishes if you don’t plan to run the dishwasher for a long while.

And as for efficient washing by hand? I’ve tested it in my own home using a Delta spray kitchen faucet with touch control, which allows me to minimize water usage when rinsing the washed dishes.

The overall energy savings when hand washing is really only realized during winter. I leave the warm sudsy water in the sink until it cools off. This heat is given off to the kitchen air, so the heating system has to run less (the same applies when taking a hot bath during cold winters). During summer, I don’t hand wash dishes to reduce the heat and humidity buildup indoors. It can actually be a double loss during summer because your air conditioner has to run longer to remove the excess heat and humidity.
The following companies offer efficient dishwashers: Asko, 800-898-1879, www.askousa.com; Bosch Appliances, 800-944-2904, www.boschappliances.com; Dacor, 800-793-0093, www.dacor.com; Kitchenaid, 800-422-1230, www.kitchenaid.com; and Miele Appliances, 800-843-7231, www.mieleusa.com.

Have more questions? Send them to: James Dulley, Colorado Country Life, 6906 Royalgreen Dr., Cincinnati, OH 45244 or visit www.dulley.com.