Kitchen and Dining

Kitchen + Dining

Kitchen + Dining

Replace a Dishwasher

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BLACK+DECKER B+D Contributor 186 Projects

A dishwasher that’s past its prime may be inefficient in more ways than one. If it’s an old model, it probably wasn’t designed to be very efficient to begin with. But more significantly, if it no longer cleans effectively, you’re probably spending a lot of time and hot water pre-rinsing the dishes. This alone can consume more energy and water than a complete wash cycle on a newer machine. So even if your old dishwasher still runs, replacing it with an efficient new model can be a good green upgrade. In terms of sizing and utility hookups, dishwashers are generally quite standard. If your old machine is a built-in and your countertops and cabinets are standard sizes, most full-size dishwashers will fit right in. Of course, you should always measure the dimensions of the old unit before shopping for a new one to avoid an unpleasant surprise at installation time. Also be sure to review the manufacturer’s instructions before starting any work.

How to Replace a Dishwasher

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    Start by shutting off the electrical power to the dishwasher circuit at the service panel. Also, turn off the water supply at the shutoff valve, usually located directly under the floor.

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    First unscrew the front access panel. Once the access panel is removed, disconnect the water supply line from the L-fitting on the bottom of the unit. This is usually a brass compression fitting, so just turning the compression nut ounterclockwise with an adjustable wrench should do the trick. Use a bowl to catch any water that might leak out when the nut is removed.

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    The dishwasher has an integral electrical box at the front of the unit where the power cable is attached to the dishwasher’s fixture wires. Take off the box cover and remove the wire connectors that join the wires together.

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    The hose is usually connected to the dishwasher port on the side of the garbage disposer. To remove it, just loosen the screw on the hose clamp and pull it off. You may need to push this hose back through a hole in the cabinet wall and into the dishwasher compartment so it won’t get caught when you pull the dishwasher out.

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    Remove the screws that hold the brackets to the underside of the countertop. Then put a piece of cardboard or old carpet under the front legs to protect the floor from getting scratched, and pull the dishwasher out.

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    Tip dishwasher on its back and attach the new L-fitting into the threaded port on the solenoid. Apply some Teflon tape or pipe sealant to the fitting threads before tightening it in place to prevent possible leaks.

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    Like the old dishwasher, the new one will have an integral electrical box for making the wiring connections. To gain access to the box, just remove the box cover. Then install a cable connector on the back of the box and bring the power cable from the service panel through this connector. Power should be shut off at the main service panel at all times.

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    Just turn the legs into the threaded holes designed for them. Leave about 1⁄2" of each leg projecting from the bottom of the unit. These will have to be adjusted later to level the appliance. Tip the appliance up onto the feet and slide it into the opening. Check for level  in both directions and adjust the feet as required.

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    Then pull the discharge hose into the sink cabinet and install it so there’s a loop that is attached with a bracket to the underside of the countertop. This loop prevents waste water from flowing from the disposer back into the dishwasher. Note: Some codes require that you install an air gap fitting for this purpose. Check with your local plumbing inspector.

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    Push an adapter over the disposer’s discharge nipple and tighten it in place with a hose clamp. If you don’t have a disposer, replace one of the drain tailpieces with a dishwasher tailpiece, and clamp the discharge tube to its fitting.

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    Adjust the L‑fitting on the dishwasher’s water inlet valve until it points directly toward the water supply tubing. Then lubricate the threads slightly with a drop of dishwashing liquid and tighten the tubing’s compression nut onto the fitting. Keeping the brass bushing between the nut and the L-fitting. Use an adjustable wrench and turn the nut clockwise.

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    Complete the electrical connections by clamping the cable and joining the wires with wire nuts, following manufacturer’s instructions. Replace the electrical cover, usually by hooking it onto a couple of prongs and driving a screw. Restore power and water, and test. Replace the toe-kick.