1:WHAT IS DISHWASHER EMERGENCY ? If leaking or burning smell.
2:SIZES? The standard size for a dishwasher is 24 inches. The large (nonstandard size is 30 inches)
3:WHAT IS AN "IMPELLER"? Impeller is necessary on the dishwashers to drain
4:WHAT IS AN "AIRGAP" A common use of the term "air gap" in home plumbing refers to a fixture that provides back-flow prevention for an installed dishwasher. This "air gap" is seen above the countertop as a small cylindrical fixture mounted parallel with the faucet. Below the countertop, the drain pipe of the dishwasher feeds the "top" of the air gap, and the "bottom" of the air gap is plumbed into the sink drain below the basket, or into a garbage disposal unit. When installed and maintained properly, the air gap works as described above, and prevents drain water from the sink from backing up into the dishwasher, possibly contaminating dishes.[2] Water flowing from the fixture into the sink indicates a need for maintenance or repair.

2 The manufacturer´s repair man states that this is a defect on all dishwashers when they are not used within a week or two.  However when it is being used at least once a week it will go unnoticed because the excess water gets drained,  if it does not get used it will start to overflow from the bottom of the door on its side.