How To Install A Dishwasher

by Darwin Hall


Installing a dishwasher requires planning for the project.

The main points to remember when planning to install a dishwasher are: location of your waterlines, the location of an electrical outlet to plug or wire the unit to, and the drain outlet that is usually connected to an undersink garbage disposer.

The best installation area for a dishwasher is next to the kitchen sink, preferably with an electrical outlet ready to go underneath the base cabinet.

1.  Preparing the opening.  It is usually best to install new flooring first so that the dishwasher can be removed for repairs or be replaced without tearing up the floor.

The flooring material should cover the space under the dishwasher so its edge won’t form a dam and trap any water that leaks.

Vinyl floors are especially suitable because they are water-resistant and can be tightly sealed.

Before installing a dishwasher, check the manufacturer’s specifications for all clearances and rough-in dimensions.  The specifications will also indicate where pipes and wires can run without interfering with the mechanisms.

See also:  Fix A Dishwasher That Won’t Cut Back On

Most cabinet openings should be 24 1/8 inches to 24 ½ inches wide.  If the installation is next to a sink, you can tap into the plumbing.

Most dishwashers require water that is somewhere between 120 degrees and 140 degrees F, unless they have a preheating feature.

dishwasher and wood2.  Roughing-in the drain hose.  A 5/8 inch diameter (inside) drain hose comes with the dishwasher.

It is usually 6 or 7 feet long.  If it is not long enough, buy more hose and join it by slipping a short piece of copper tubing inside both hose ends and clamping the ends of the hoses tightly around the tubing.

Most codes require that the drain hose have an air gap to prevent overflow from a clogged sink drain from siphoning back into the dishwasher.

This device is mounted in a hole in the sink deck or countertop.

The drain hose is connected to the air-gap inlet under the counter, and another short hose connects the outlet to the disposer or sink drain.

Water can flow only one way through the air-gap.  If you are not required to install an air-gap,  you should still loop the drain hose up to the bottom of the countertop and attach it there with a clamp.  Then run the hose into the disposer or sink drain.

3.  Roughing in the hot-water supply.  The dishwasher should have it’s own valve.  Install a tee in the hot water supply pipe running to the sink faucet or run a new hot-water line under the floor and stub up into the dishwasher space.

Check specifications for the size of the tubing needed to connect the valve to the dishwasher (usually 3/8 inch), and be sure the valve has an outlet for a compression fitting the size of the tubing.

4.  Roughing in the electrical wiring.  Dishwashers are usually required to be on a separate circuit protected by one 20-amp breaker, but in some cases you may be able to wire the dishwasher into the same circuit as the disposer.  Check your local code.

If the dishwasher requires it’s on outlet or junction box, check the manufacturer’s specifications for locating it.

Some units have a standard household cord for plugging into a wall receptacle, often located in the dishwasher space or under the sink.  Others have a shortened cable for wiring directly to the junction box.  Still others include their own junction box for mounting on the floor.

5.  Installing the dishwasher.  Slide the dishwasher in place and secure it to the floor with lag bolts or heavy screws.  Make connections, usually underneath the unit, according to the manufacturer’s instructions.

Watch the VideoTurn on the circuit breaker and the water supply valves and run the machine through a cycle test.  If everything checks out, secure it to the countertop and install the base panel.

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