Installing a built-in dishwasher requires basic mechanical, electrical, and plumbing skills, so the average handy person can install a dishwasher in 1 to 3 hours depending on if it is a new installation or a replacement dishwasher. If you are replacing an existing dishwasher, it will take less time.

New Installation

1. Prepare the cabinet area in which the dishwasher will be installed. The opening should be 24 inches wide for most models, 24 inches deep and 34 1/2″ from the floor to the underside of the countertop. The back wall can not have pipes or wires on it. The power and water supply lines will come into the cabinet in the 4″X4″ area at the bottom back of the cabinet through a 1 1/2″ hole. Make sure the floor is level and the cabinet is squared.

2. Choose your drain method based on your local codes and height of the drain tee. Some codes require an air gap. If the drain tee is less than 18 inches from the floor, you must use an air gap. If an air gap is not required and the tee is over 18 inches from the floor, you can use the loop method for the drain connection. If the drain hose will be connected to a garbage disposal, you have to remove the knock out plug so that the dishwasher will drain.

3. Inspect or install wiring by making sure there is a 120V, 60Hz dedicated circuit with a 15 or 20-amp breaker or time delay fuse. Wiring has to be 2 wire with a ground and rated for 75 degrees Celsius or 176 degrees Fahrenheit. The wiring can come into the cabinet from either side in the rear bottom area. The hole should be a maximum of 1 1/2″, and it can be the same hole used the the water supply line and drain hose if its being hardwired. If it is a flexible power cord, it must have a separate hole. Hardwiring cable will come up the right side along the bottom 24 inches of the cabinet to the right front electrical connection on the dishwasher.

4. Prepare the water supply line that enters through the 1 1/2″ hole in the rear bottom of the cabinet. Turn off the water to install a hand shut-off valve under the sink. The water connection is on the left side of the dishwasher. Use 3/8″ O.D. copper line to extend a minimum of 19 inches from the rear wall. The water heater should be set between 120 and 150 degrees (closer to 120 if children are in the home to prevent scalding accidents) and the pressure should be between 20-120 PSI.

5. Prepare the dishwasher by checking the door balance and adjusting the spring tension if necessary. If the legs have to be attached, do that close to where it will be installed.

6. Connect the drain hose to the dishwasher's drain port if it did not come factory-installed. Position the electrical wiring and water supply lines so that the base of the dishwasher will not catch them. Slide the dishwasher in front of the opening so that you can feed the drain hose through the hole you drilled for it.

7. Inch-by-inch slide the dishwasher into the cabinet as you fee the drain hose through its hole. Stop with a few inches left and make sure nothing is kinked or pinched. If all is in good order, push the dishwasher all the way in so that the edges of the door are behind the cabinet frame. Test the door for smooth opening and closing.

8. Level the dishwasher front to back and side to side by adjusting the leveling legs.

9. Align the brackets and secure the dishwasher to the countertop according the manufacturer's instructions.

10. Through the access panel, connect the water supply line and electrical supply. Also connect the drain hose under the sink. You are ready to do a wet test with the “rinse only”
cycle. Check for leaks and proper draining.

Replacing an Existing Dishwasher

You will not need to drill the holes since they will already be there from the existing dishwasher. However, you do need to inspect the wiring and plumbing to make sure they are capable of servicing the new dishwasher. Once that is established you should turn the power off at the main and turn the water supply off before beginning the removal of the old dishwasher. All lines and wires must first be disconnected. Take the drain hose off the garbage disposal or drain pipe under the sink. If the dishwasher has a power cord, you need to unplug it. If the dishwasher is hardwired, you have to open the access panel and electrical junction box. Remove the wire nuts and disconnect the black and white wires. Also remove the ground screw to disconnect the green ground wire. Use a catch pan while disconnecting the water supply line. Once all of these lines and wires have been disconnected, you can take out the screws and brackets that hold the dishwasher in its place and carefully pull out the old dishwasher.

Then follow the same procedures to install the new dishwasher with the exception of drilling the holes and running the wiring and water supply lines.

Once you have installed your new dishwasher and tested it for leaks, you are ready to start cleaning.

Source by Dan Tardio