It is fairly straightforward to install.
You will need:
1. A right-angle pipe connector of the appropriate diameter for the disposal outlet and existing pipe. One end should have a gasket that will screw onto the disposal, the other end is plain pipe. Make sure both ends fit!
2. A pipe-cutting wire saw to cut existing pipe to accommodate the new configuration.
3. Pipe primer & glue (ask someone in store for appropriate type)
4. Straight pipe connector (after you cut out a section of pipe, will need this to bridge the remaining ends)
5. Teflon sealing tape (the disposal outlet will screw into the pipe, use this tape on the threads to ensure a good seal if there is no washer in the connector gasket).
Depending on how the pipe enters from the wall to the sink, you may have to cut out a portion of the horizontal part coming out of the wall (prior to the U-trap) to accommodate the right-angle connector and garbage disposal's width, then bridge to two cut ends with the straight connector. Make just one cut first so you can adjust the vertical portion, proceed with the steps below, then make the second cut when ready to permanently seal things together.
Mount the top of the disposal into the bottom of the sink using the sealing material and brackets provided with the disposal. Rotate the dispenser so that the outlet is ideally at a right angle to the drain pipe heading into the wall. This will make it easier to access than if it is in-line (reaching behind the disposal). You will see while fitting pipes below that you may have to rotate the disposal to get the best fit for the outlet to the drain pipe.
Cut the vertical pipe that led from the sink drain to the appropriate height to accommodate the right-angle connector to the disposal outlet. It's best to under-estimate the amount you need to remove, fit things together (without the pipe cleaner & sealant, of course!), and cut a little more to achieve proper fit. There will be some amount of lee-way, but you want to maximize the amount of overlap between the right-angle connector and the pipe. Remember you will need to attach the horizontal part downstream of the U-trap back to the wall. If the vertical portion is too short or long, and the cut horizontal ends are out of alignment in the vertical plane, the pipe will have to bend and this stresses existing pipe joints within the wall.
Now, this is key: dry-fit the vertical pipe to the disposal outlet with the right-angle connector. You may notice that the horizontal pipe ends that you previously cut are out of alignment in the horizontal plane. You will need to rotate the disposal and the right-angle connector until they are back in alignment.
Once you have a good vertical fit and the horizontal ends are re-aligned in both vertical and horizontal planes, figure out how far back to make the second cut in the horizontal pipe coming from the wall. Remember you will bridge with a straight connector, so account for its internal length also.
Dry-fit everything together. If there is no tension from pipes bending, it will seal well. Proceed from disposal downstream to horizontal pipe while sealing. The purple stuff is caustic, apply it liberally to the ends that will be joined, then let it dry. The sealant is sticky. Apply a thin coat to both ends, fit them together, and twist slightly to spread the coat evenly within the pipe. Use gloves for this part as both chemicals can burn your skin! You should do one joint at a time instead of spreading it on all the joints and rushing to fit everything together.
Feel free to PM me if you have questions!
