Improperly installed DW - Air gap. Permanent damage? Proper install?

**svs128** · 01-18-2011, 08:17 AM

I have two questions. Is my DW installed correctly? Has it been damaged from being used while improperly installed? Here are the details....

My DW does not drain through a sink. It's drain hose connects to plumbing in the basement. According to the DW installation manual, an air gap is required for this type of set up. I found this on page 1 of the Frigidaire DW (model FGHD2433K) manual. See section 4.3, under figure 6 - http://manuals.frigidaire.com/prodin.../154427301.pdf

My DW was installed in July 2010. It ran great for 3 months - very quiet and super clean dishes. Unfortunately, it has been downhill since then. It slowly started sounding like a jackhammer during the latter 2/3 of a run. Frigidaire recommended a local appliance repair company and a technician came out on 1/4/2011. He determined that it was installed improperly - no air gap.

The installation has since been fixed... I think. The original installer (a local reputable plumbing company - not handyman or DIY) come back out on 1/ 14/2011.

This was the original set up we used for 6 months: DW drain hose ran through floor and connected directly to a pipe in the basement that connected directly to our main sewer line in the basement. No P trap and no air gap. Drain hose is looped on side of DW as required.

Here is the new set up: DW drain hose runs through the floor and connects to the same pipe as our washing machine in the basement. This pipe runs approx 6 feet up a wall. Washing machine connects at the bottom and DW at the top. The top of the pipe connects to a P trap and then to our main sewer line in the basement. Does this sound OK?

Now, after the new installation, the DW is slightly quieter, but still loud AND doesn't clean; leaving small particles and film over all the dishes and glasses.

Also, if you need more description of the drain plumbing, I can provide it. A tech is coming back to look at the noise/cleaning issue again. All I know is that the non airgap installation might have caused siphoning of the wash/rinse water. Can siphoning cause damage to a DW? Should the original installer replace the DW?

hj · 01-18-2011, 11:07 AM

I have absolutely no idea how the "new setup" looks because it is too convoluted to determine where the various connections are. A dishwasher without a PROPERLY installed air gap CAN siphon the water out of the tub, whether it does or not depends on the timing of the fill cycle compared to the drain phase. The only possible damage would be to the heater if it was operating without water around it. IF the water siphons out, it CANNOT clean because there is no water to do it. AND, if the hose goes from the DW directly into the hole in the floor, the water will usually drain out as fast as it is entering the DW. The air gap, if you install one MUST go on top of the cabinet, not in the basement or anywhere else.

**geniescience** · 01-18-2011, 11:37 AM

a counter air gap = "fix". Is this what you wrote when you said "fix"? Not below the floor.

Originally Posted by svs128

The installation has since been fixed...

I opened the PDF. It does mention that the hose could go below the floor. (It also shows S traps instead of P traps, btw.)

If my reading of your situation is accurate, the problem changed; it's now different. It used to be a jackhammer in the last 2/3rd of its cycle. Now, it just doesn't clean. And this change happened exactly when the air gap got installed. Is this what you wrote?

And it had a high loop before. Y / N ?

hj · 01-18-2011, 04:57 PM

High loop only works for a disposer connection. When connected to a trap under the floor, it becomes a "perfect siphon tube".

**svs128** · 01-19-2011, 04:49 PM

geniescience - Air gap does not = fixed. No air gap was installed the first OR second time around. I still have two issues - jackhammer noise and not cleaning. After using the DW today, I can add some other very weird noises to my problem (grinding and squeaking). Another development - while using the DW today the drain hose disconnected in the basement and leaked water everywhere.

The original installed is coming back out ASAP. Does anyone have a detailed diagram of how to drain a DW below the floor without a sink? It would be great to just show him and picture and say "DO THIS!." It would also help me check his work.

A picture of my layout is available here:http://www.flickr.com/photos/57286676@N08/5370972887/ The back of the DW is accessible via the basement stairs.

**cacher_chick** · 01-19-2011, 05:01 PM

You need an air gap installed ABOVE the level of the dishwasher on the countertop. The drain must go up through the air gap before it can go down.

The other noises might or might not be damage from the dishwasher running without enough water in it.

**DavidTu** · 01-20-2011, 12:18 PM

I've heard some dishwashers not require an airgap above the counter b/c they are built in to the machine. What is the scoop on that (and Terry: is it allowed in Seattle?)

**mcconnellplumbing** · 01-25-2011, 01:12 AM

In OKC, we route the drain line over to the kitchen cabinet space where it is looped up high, bracketed, then drops back down to the disposal in most instances. Some of the D/W manufacturers install a loop bracket on the back of the D/W to make sure the loop is installed and not simply ran over to the garbage disposal. Without the hig bracketed loop, water from a full sink draining through the disposal could run downhill back into the D/W through the drain hose. Inspectors here suggest the hole through the cabinet to be high and thus the inspector knows the drain hose is looped high and will not allow drainage back into the D/W.

**cacher_chick** · 01-25-2011, 03:08 PM

Originally Posted by mcconnellplumbing

In OKC, we route the drain line over to the kitchen cabinet space where it is looped up high, bracketed, then drops back down to the disposal in most instances. Some of the D/W manufacturers install a loop bracket on the back of the D/W to make sure the loop is installed and not simply ran over to the garbage disposal. Without the hig bracketed loop, water from a full sink draining through the disposal could run downhill back into the D/W through the drain hose. Inspectors here suggest the hole through the cabinet to be high and thus the inspector knows the drain hose is looped high and will not allow drainage back into the D/W.

This is great, but the post is about a D/W that is not draining to a disposal or sink p-trap. They need an air gap to prevent siphoning.

**geniescience** · 01-25-2011, 04:30 PM

Or, a standpipe. But only if the standpipe is in the same room (on same floor level as the DW).

svs, I re-read the thread and i see you have the drain hose now going into your washer's standpipe, and That Was The "Fix"...

This is not good enough. As cacher_chick and hj wrote, it needs an air gap if it goes down thru the floor, or else it siphons itself dry. (afaik.)

svs, the image you need to post is one of the hose and drain pipes. The only thing to show plumbers is an image of the hose and drain pipes. The geometry of those pipes. Not a picture of your kitchen.

**svs128** · 01-26-2011, 10:56 AM

Thanks for all the advice. Everyone pretty much confirmed that we needed an air gap. Armed with this advice and the installtion manual, I have resolved the issue.

The plumber came back on Friday, the 21st, and installed an air gap above the level of the dishwasher. The DW is cleaning A-OK now. Still making some draining noise but I believe that is a seperate issue. Thanks again.