Garbage Disposal Types and Features
Disposals come in continuous feed and batch feed types. Continuous feed disposals are most common and easiest to use. They are the open mouth disposals that turn on and off with a wall switch. Batch feed types of disposals require you to place the waste food into the hopper chamber, close a stopper lid to activate the grinder and then the food is pulverized. Batch feed types are more expensive and safer for people who have a hard time keeping their hands out of small holes filled rotating knife blades or can't seem to keep cutlery out of the disposal. Fortunately most of us can handle these basic skills and continuous feed disposals are just fine and the most commonly used.
You'll find that disposals come mostly in a range of motor sizes including 1/3 HP, 1/2 HP, 3/4 HP and 1 HP. If you're grinding only soft foods like vegetables, then 1/3 to 1/2 HP is fine. But paying a bit more for a 3/4 to 1 HP motor will provide you less jams and smoother operation and finer pulverization of the food waste, and that means less clogged drain lines and less stress on the waste water system. I recommend buying at least a 3/4 HP disposal.
The grinding chamber is where the action takes place. Smaller HP motors will have smaller chambers because they have limited torque and limited power to pulverize the food waste. Conversely, larger HP motors will usually have larger food grinding chambers because they can handle more waste food volume. In addition to a minimum 3/4 HP disposal, I also highly recommend a food chamber that is stainless steel or at least glass filled nylon. This will be the easiest to clean and will not rust. I really recommend the impellers be stainless steel.
Although all disposals are somewhat noisy, there is still a big difference between cheap small HP units and better quality, higher HP, insulated grinding chamber units.