Plumbing - How To Install a Garbage Disposal
These days most garbage disposal unit installations are really replacements. Fortunately, that requires only simple tools and a little bit of guidance.
Garbage disposals are actually attached to the sink by a flange. The pipes attached provide some support, but are mainly for inputing and flushing out water. So, the key step is to undo the flange. But first, the pipes....
First, turn off any electricity to the garbage disposal. In some cases, that's as easy as flipping an under-sink switch. Usually it will require flipping off the circuit breaker that controls the supply to the garbage disposal. Don't rely solely on having the disposal turned off at the above-the-sink wall switch.
Next, depending on the design, it may be necessary to turn off the main water supply for an hour. Some plumbing designs make it necessary only to close the valves under the sink. The goal is to ensure that no water can run when you disconnect the pipes from the disposal.
Remove the electrical connections. Sometimes that's just a small plastic connector. Other designs require removing a plate and disconnecting wire from flathead screw mounts.
Then remove any attached hoses. Carefully clean the interiors of any remaining Teflon plumber's tape.
Next, using a pipe wrench or channel locks, loosen the nuts holding the pipes onto the disposal unit. Carefully remove any traces of Teflon plumber's tape here, too. A little sandpaper may be needed to get the interior clean.
Now the disposal unit should be attached only by the flange in the sink. There will be a large nut that holds the neck of the unit to the flange and possibly a mounting ring. Since most units last a long time, it may be corroded and stuck. A jerk on the wrench is more effective than a twist, but take care not to damage anything under the sink.
Once the flange nut and any mounting ring is removed, the thin metal part may or may not come out easily. Most will have been installed with plumber's putty, which solidifies over time. It's a mild adhesive, but it can require some force to get the flange loose.
Once the flange is removed it will not usually be needed again. New garbage disposal units come with a replacement as part of the kit. Thoroughly clean off any remaining putty from the sink. It's critical to have clean, flat surfaces in order to prevent any leaks.
A 1/4 inch bead of new plumber's putty around the surface will usually be enough. Drop the new sink flange into place and seat it accurately. Press down to squeeze out any excess plumber's putty, then wipe off the remainder before it has a chance to dry.
Most units will have a plastic or rubber gasket to fit on the underside of the sink. Slip them into place along with any other mounting rings that came with the unit, according to the instructions. Designs differ, but use all the parts that came with the unit. Tighten everything in place in preparation for the unit using supplied nuts and/or screws.
Many garbage disposal units will have a plate on the bottom to which the wires will attach. Others have a small outlet and the wire assembly just plugs in. Wire the unit according to the instructions.
Press the unit up onto the mounting assembly/flange. Apply Teflon plumber's tape to any hose nibs and re-attach all the hoses. Tighten the mounting ring and any clamps and you're almost ready to go.
Test for water-tightness before turning the circuit breaker back on.
