Plumbing – Dishwasher drainage problem

dishwasherdraindrainagemotorplumbing

I recently got a "new" (used) dishwasher and have installed it myself. It is a Frigidaire Ultra Quiet iii. There is a problem with it draining water. Here is what the setup looks like:

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The pink is the drainage hose. Note that the hole in the side of the wall is near the ground while the pipe is about 2ft off the ground.

The water does not drain (at least not fully). There is always a little puddle in the bottom of the diswasher. I've researched a bit and found some discussion about a high loop. So I tried that. I used the clips on the side of the dishwasher to make a loop:

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This still does not properly work. I checked the end of the drainage pipes and there doesn't seem to be anything blocking in there (I put a screw driver in and it's clear, plus the sink drains just fine).

So to diagnose, I disconnected the pipe end of the hose and put it into a bucket just to see if it drains, like so:

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THIS WORKS!

It drains very well into a bucket. The pump is clearly doing it's job.

So my suspicion is that the 2nd loop is a bit tough for the pump to push through. Could that be correct? The fix would be to drill a hole near the top of the wall such that there is no loop down before it goes into the drainage pipes. Before I drill, I just want to confirm that this could be the issue.

Thanks for the help!

Best Answer

The drain loop is taking the place of a vacuum breaker you'd see on the counter. The loop really has no bearing on how the machine drains. It only stops (hopefully) water from flowing back to the DW from the drain. The pump is obviously working correctly as you mentioned when you checked with a bucket. What you didn't mention or check was whether the DW was empty of water. In fact unless the water level inside is sloshing around, some residual water will most likely remain simply because the impellers cant force small amounts of liquid out the hose. Some will remain in the sump at the case bottom and then pumped out on the next drain cycle. Your first and only loop should be above the drain where the hose enters the sink drain. Make the top of the loop touch the counter top underside. Unless your DW pump is faulty or damaged it will expel water easily through the loop and down the drain.