How to Install a Dishwasher
A new dishwasher in 10 easy steps
Boy, the retired couple you bought your house from left behind one incredibly energy-efficient dishwasher! Okay, maybe just efficient to them, because they didn't need to run it more than once a week and only had a full load when the grandkids came for Thanksgiving. But you—you pack that thing with pots, plates, and glasses every night, sometimes again in the morning. Its age is starting to show, especially in your electric and water bills.
Time to switch it out for a new Energy Star–qualified dishwasher, which can save you more than $30 a year on power and almost 500 gallons of water. These units have sensors that self-adjust to wash with just the right amount of water. And today's models are so good at scrubbing, you don't have to prerinse in the sink—which translates to even less of your hard-earned money and time down the drain. But the biggest cost-saver of all is that you can install one yourself in an afternoon, as This Old House technical editor Mark Powers demonstrates on the following pages. No plumber, no electrician—and no worries that you're squandering your retirement money on a load of clean dishes.
Energy-efficient and water-saving dishwashers may have the most up-to-date technology, but thankfully they have the same three basic connections dishwashers have been using for decades: a water supply, a drain line, and an electrical hookup. That means if you're replacing a dishwasher, you only need to break these connections from the old appliance and reattach them to the new one. (Shut off power at the breaker panel and close the hot-water valve under the sink first, and be sure to unscrew the old unit from the underside of the counter before pulling it out.)
The existing electrical wiring is still good, but both plumbing lines should be replaced. Dishwashers come with drain hoses, but you'll need to buy a supply pipe—preferably copper tubing, which TOH plumbing and heating expert Richard Trethewey uses instead of braided steel. "Copper is time-proven," says Richard. "Inside a braided line is rubber, which can eventually fail. Copper lasts 60 to 80 years—longer than any dishwasher."
Though traditionally dishwashers get hooked up to the hot-water supply, you can save even more energy by connecting to the cold water because the heating element in the dishwasher uses less power than a water heater. However, check manufacturers' literature—some companies' models must be supplied with hot water.
The most difficult part of the installation may be snaking the copper tubing through the cabinet without kinking it. An invaluable tool for this is a tube-bending spring, which fits either inside the pipe or around it and bends it with even pressure. But Richard points out that it's the easiest of the connections—the drain line—that actually causes the most trouble. It must be installed strapped up high in an upside-down U to prevent sink backflow from going into the dishwasher. Also, if you're installing a model that sits flush with the front of the cabinets, you may have to drill new, lower holes from the dishwasher bay to the supply valve so the plumbing lines snake along a narrow inset at the back of the unit, allowing you to push it all the way to the wall.
Luckily, the electrical connection is fairly straightforward; just make sure to clamp the wires - be they metal-sheathed BX cable or vinyl-wrapped Romex - to the unit's junction box. This protects against electrocution should there be any leaks.