Air gap issues with kitchen sink to dishwasher

[MikeKenmore]

i'm reconnecting my plumbing following a kitchen remodel.

we reused the dishwasher, but the sink and faucets are new. our old sink was a two bowl setup and the current is a single bowl sink with the disposal directly attached below.

i'm having an issue with the air gap connection. i've run the 5/8" line up from the dishwasher to the air gap and the 7/8" from the disposal to the air gap. this is the same connection as far as i can tell with our old setup which never had an issue.

now, however, i get water shooting out the airgap into the sink when i run the dishwasher. i tried blowing out the air gap (not the best effort in the world, but i was getting resistance from water), but that didn't seem to do anything.

any thoughts on what's going on?

 

[Bluebinky]

Did you remove the knockout in the disposer?

 

[Sponsor]

 

[MikeKenmore]

sorry. the disposal is the old one too, so yes, it was functioning before hand.

 

[MikeKenmore]

one thought i had is that it could be the 7/8" line. i don't have a clean shot to the air gap, so i have a J-shape coming from the disposal to the air gap. i think it all flows downhill, but it's probably close in spots.

 

[Widgit Maker]

It is most likely you have a crimp in the hose from the air gap to the disposal restricting it's flow.
Suggest that you disconnect the trap and hose from air cap, spin the disposal from it's present position of 3:00 o'clock to 10:00 o'clock. Turn trap and reconnect to disposal. Then reconnect the hose from the air gap.

 

[Plumbs Away]

Make sure the disposer inlet is clear. I have encountered situations where the inlet was blocked from the natural accumulation of "disposer gunk," so the water draining from the dishwasher had nowhere to go but out of the air gap. This should not happen, however, if the dishwasher is used regularly.

 

[Smooky]

The air gap fitting has to be connected correctly. Maybe it is backwards.

 

[Reach4]

Try taking a photo of the underside of the air gap. If you are using a camera, put it into macro mode before reaching under the sink bowl and snapping the picture.

 

[MikeKenmore]

widgit maker: your suggestion is how i originally had my disposal in there. alas, the p-trap interfered with the backside of the sliding drawer (by about 1/2" vertically). i really don't have much room there. i think i might be able to rotate to 12:00 or 1:00 and get a cleaner shot for the 7/8" line.

 

[Widgit Maker]

OK, the purpose is to not have any sharp bends in the hose from the air gap where it might kink. Try rerouting the hose. Try following the dishwasher hose down then make a gentle bend around to the disposal. Kink is probably up close to the underside of the sink. What is holding the hose up in that position?

How about switching the location of the air gap and the soap dispenser? That would give you a straight shot to the disposal.

 

[MikeKenmore]

the 7/8" hose is pretty rigid. it took some effort to get it in that position in the first place. any tighter of a radius and i think it'll kink for sure.

i toyed with the idea of swapping positions of the surface mounted items, and that might ultimately be a better choice than replumbing things (using solvent weld at the wall connection and figuring out how to cram more crap and bends behind the disposal).

i like the soap where it is (out of the way of the water flow from the sink). i suppose i could swap the air switch on the disposal (though my line might be a smidge short now after i cut it)

 

[Reach4]

If you wanted to troubleshoot, you could disconnect the 7/8 hose from the disposal/disposer and feed the water into a bucket. If you still get water out of the air gap fixture, you would know that that air gap fixture will not work.

Of course you would want to be sure how to cut the water pumping before the bucket fills.

It looks like you have 5 holes in your sink behind the bowl. If we call the hole with the air gap #2, could you move the air gap to #4 and leave the soap dispenser in hole #5, or does that interfere with the operating handle

 

[rjbphd]

Remove the useless air gap and pipe the dishwasher drain right to disposal.. the drain hose must be up against under countertop.

 

[MikeKenmore]

i'm going to try swapping locations of #2 and #4 (air gap and air switch).

is there any chance the 5/8" from the dishwasher has some kind of issue that would be affecting the performance of the air gap?

thanks

 

[Reach4]

I am not a plumber, and I don't have relevant experience. But I don't think that any flaw in the incoming 5/8 could do anything to increase the flow. And lower flow would make it it less likely you would get water out of the air gap.

The fact that the input port on your air gap is smaller than the output port makes it highly unlikely that you reversed the lines. You are using smaller line from the dishwasher and the larger 7/8 to the disposal.

One thing I might try is to see if the problem happens if you run the disposal while the water pumps. Now I don't have an answer as to what you would do about it based on the result... I know that often disposals accept water faster when running. If the air gap did not emit water in that case, I guess it would point to the problem not being as serious as a kinked line.

It seems odd to me that there is not easy-to-find comparison of dishwasher air gaps. There are a lot of comparisons written comparing many other things.

I see there is a copper air gap available in the $3x price area. I wonder if that would work better. I don't know if it would be better or not. Maybe somebody will publish a test as to how many GPM they can put through a few air gaps before water comes out the side.

 

[MikeKenmore]

got it figured out. it WAS the knockout in the disposal! i guess the previous setup didn't use the disposal for the air gap setup and must've done a direct discharge to the drain line. i should've looked more closely. instructions for troubleshooting should be something like:
1. check to see if plugged in.
2. check to see if knockout is removed in garbage disposal
...

lesson to self: never assume