DIY Appliance Repair: How to Replace a Garbage Disposal

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John W. Hammes of Racine, Wisconsin really loved his wife and wanted to make her woman's work easier for her. An architect by day and an amateur inventor by night, he invented and patented the first garbage disposal unit in 1927. John sold manufacturing r

Garbage disposal units have come a long ways since John W. Hammes produced the first “Electric Pig” in his basement workshop 85 years ago. The modern version of that first garbage disposal is much more efficient, much more reliable, and only a fraction of the size of its grand forerunner. Today's garbage disposal units, with proper care and maintenance, will last for ten to twelve years. Still, the modern “Electric Pig” has a hard job to perform in its job of making the lady of the house's woman's work less arduous. Eventually the “Pig's” bearings start to wear out and the rotating cutters become nicked and dull. Motor bearings can be replaced and the nicked, rotating cutter can be replaced, but with the cost of garbage disposal units dropping more everyday, it is ofter easier and cheaper to replace the older “Electric Pig” with a new state of the art disposal.

Replacing a garbage disposal is so easy that even a rank beginner can do it as long as he or she allows him or her self sufficient time.

Purchasing a new garbage disposal unit.

The prices are dropping everyday. Entry level garbage disposal units that once sold for $300 can now be bought for $50 and the top-end stainless-steel models that once sold for $500or more can now be found for $250 to $300. Entry level models that come with a 1-year warranty will, with proper care and maintenance last five to ten years or longer.

Tools and Supplies that you will need for this project.

  • Non-Contact Voltage Tester

  • Screwdrivers

  • Long-Nose Pliers

  • Nut-Drivers

  • Electrician Pliers

  • Tongue-and-Groove Pliers

  • PVC Cutter

  • Roll of Plumber's Putty

  • Installation Kit that came with Disposal Unit

Preparing to replace Garbage Disposal unit.

The very first thing that you will need to so is to turn off the branch circuit breaker on the main service panel controlling the power to the disposal unit.

Then, once you have removed the terminal cover plate from the bottom of the disposal unit, use the non-contact voltage tester to double-check that the circuit is actually safe to work on. Once you have confirmed that power is off, disconnect the wires from the old disposal and remove the Greenfield Flex from the side of the motor.

Remove the old garbage disposal unit.

Begin by disconnecting the dishwasher drain hose, as shown in the above photo, if there is a dishwasher installed. Then disconnect the main drain fittings, using the Tongue-and-Groove pliers if the flange nuts cannot be loosened and removed by hand. Once you have the drain fitting removed, loosen the nuts securing the disposal unit to the mounting flange.

Disposal units mount in several different ways. Some use a three bolt mounting system, some use large hose clamps, but the ring assembly method shown in this tutorial is the most commonly used method.

To remove the unit, turn the mounting flange counter clockwise until the disposal comes free of the drain. Once the disposal is off the drain assembly, remove the three flange bolts, pry off the retainer ring, and push the drain assembly up through the hole in the sink. Scrape any remaining putty or caulking off the sing drain area.

Install the new drain assembly.

Begin by working a mound of Plumber's Putty into a 10-inch long, 1/2-inch thick rope by rolling it around on the kitchen counter-top. Once you have

formed the putty into a rope, press it around the drain flange as shown in this photo.

Then press the flange through the hole in the bottom of the sink. As you will see in this next photo, some of the putty will be forced out through the hole.

To finish the new drain installation, place the new cardboard washer on the bottom ring and slip the ring over the drain spout.

Next, slip the mounting flange over the drain spout, as shown here,

and snap the retaining ring into the groove machined into the drain spout. Finally tighten the retainer bolts until almost all of the Plumber's Putty is squeezed out between the flange and the bottom of the sink as shown here.

Preparing the new disposal unit for installation.

You will find it easier to wire the new disposal unit before installing the disposal unit on the sink drain.

Install the Greenfield Flex connector, the flex, and wires in the bottom or side of the disposal unit. Connect the ground wire to the grounding screw and wire nut the black and the white circuit wires to their corresponding motor pigtail leads. Double check your pigtail connections by tugging gently on the wires before installing the terminal cover plate.

Before lifting the disposal unit into place, poke the dishwasher fitting plug through with a screwdriver. Make sure that you reach inside the disposal with free hand to catch the plug as you poke it through. Make sure the plug does not remain inside the disposal.

If you do not have a dishwasher to connect, skip this step.

Installing the new unit on the sink.

Lift the garbage disposal unit into place and engage the tabs.

Insert a flat-blade screwdriver in one of the tab slots and rotate the whole unit clockwise until the mounting ring bottoms out.

To begin plumbing the disposal drain, install the rubber gasket on the flanged end of the drain's crosspiece and slide the metal flange on the crosspiece from the other end.

Insert the metal flange in the groove machined in the drain outlet on the disposal. Then insert the flange bolt through the top of the flange and tighten in place.

Trim the new crosspiece to length using a PVC Cutter and reassemble the sink's “P” Trap.

Turn on the water and check for leaks. Turn on the circuit breaker and give your new “Electric Pig” a test run.

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