Hooking up dishwasher drain question
I just had a remodel done to my kitchen. I had a peninsula built and moved the dishwasher from next to the sink over to the peninsula. The plumber (30 years experience) hooked up my dishwasher by drilling a hole through the tile down into the cellar and connected the drain hose to a 2" drain pipe which was formerly used for my washing machine before we built a laundry room on main floor 20 years ago.Hence, this pipe has not been used for 20 years. This 2" pipe connects to the main drain for the kitchen. In the meantime, right after the plumber left, the stove installer come to install my new stove. He went down into the basement to check the circuit box for the stove installation, and noticed the new plumbing for the dishwasher and proceeded to tell me that it was done incorrectly, not to code, and that I may burn out my dishwasher motor and have water siphoning up back into the dishwasher. He said that the drain hose must be hooked up 20 inches above the kitche floor to eliminate this. The plumber did not do this because did not want to drill through my new cabinets, and also said that the hose would lay inside the cabinets and may get disturbed and promote leaking. This is why he went through the floor. He said this was the easiest and most sensible what to do this since the old washer drain was already there in place and connected to the main drain/ Again, he is very experienced, I called him to tell him what the stove installer said and he said basically he was wrong and that it was done correctly and that he does jobs like this in kitchen islands all the time. He said something about there being a "trap" in the pipe downstairs. I don't know what this really meant.
So, who is correct????