Dishwasher and disposer rules

[Jeffrey R. Pope]

Originally Posted by rmaday

Local Code takes precedence over manufacturers instructions, yes?

Actually, no. In most cases, the manufacturers requirements override local code. The common exception is when those requirements are in direct contradiction to local codes.

In other words, if there is any ambiguity, you follow the manufacturers requirements.

For example, California's requirement is very clear;

CPC 807.4 No domestic dishwashing machine shall be directly connected to a drainage system or food waste disposer without the use of an approved dishwasher airgap fitting on the discharge side of the dishwashing machine. Listed airgaps shall be installed with the flood level (FL) marking at or above the flood level of the sink or drainboard, whichever is higher.

[relliott]

My cigarrette package says light and enjoy,but they still tell me I will get a ticket if I smoke. Go figure.

[Rick Maday]

Originally Posted by jpope

Actually, no. In most cases, the manufacturers requirements override local code. The common exception is when those requirements are in direct contradiction to local codes.

In other words, if there is any ambiguity, you follow the manufacturers requirements.

For example, California's requirement is very clear;

CPC 807.4 No domestic dishwashing machine shall be directly connected to a drainage system or food waste disposer without the use of an approved dishwasher airgap fitting on the discharge side of the dishwashing machine. Listed airgaps shall be installed with the flood level (FL) marking at or above the flood level of the sink or drainboard, whichever is higher.

Thanks for the clarification.

I did notice in reading some dishwasher install instructions on line that for this particular question the manufacturer gives you an either / or option and defers to local codes.

[relliott]

Makes sense ,or they would not even have a knockout

[James F. McKee]

I haven't seen a new dishwasher in years that the drain line was not factory mounted up over the chasis and then back down ...would this not satisfy the air gap need???

[Jeffrey R. Pope]

Nope. An air gap and a high loop are different, although they're intended to perform similar functions.

In CA it's clear. The air-gap must be a listed component and it must be installed above the flood level of the sink or basin.

High loops are not secured above the flood level, but rather, the highest point beneath the sink or cabinet, so there is still the potential for cross-contamination.

[James F. McKee]

does that not seem a bit like splitting hairs Jeff?

[Jeffrey R. Pope]

I don't believe so, no. One method eliminates the potential for cross-contamination, while the other method simply reduces the potential.

Notice the discoloration in the drain line in this picture. Even if there is a high-loop behind the washer, there is the potential for this "muck" to be drawn back into the dishwasher.

[James F. McKee]

I guess i see what you mean , although i think that in that picture it is apparent that the over the top of the chassis loop was abandoned and the drain line was brought in from the bottom of the cabinet....thanks....jim

[Jeffrey R. Pope]

You are correct about the configuration, but the point is this - The high-loop is a closed system, or vacuum (if you will) where there is always the potential for cross-contamination. The air-gap eliminates the closed system, just as with the anti-siphon valves required on exterior spigots.

The only way for an air-gap to fail, is if it were to become submerged, which is why it's required to be above the flood level of the sink.

[James F. McKee]

thanks Jeff

[relliott]

Not all models have the loop built in and it should still be bracketed up high.
I spent six years installing the things.
Yes an air gap is required but cross contamination would be very difficult as this is a drain system rather than a supply pipe.
By the way another reason for high mounting is to get it out of the way.

[William J. Decker]

Originally Posted by relliott

Not all models have the loop built in and it should still be bracketed up high.
I spent six years installing the things.
Yes an air gap is required but cross contamination would be very difficult as this is a drain system rather than a supply pipe.
By the way another reason for high mounting is to get it out of the way.

The "high loop" is supposed to be braketed to the underside of the countertop. Around here, most are stone. ABT, the large appliance supplier around here, always installs them wrong. They also use those stupid foile clothes dryer vent hoses, which are also not allowed.

Go figure. More work for us.

[Jack L. Gilleland]

No matter how they mount that loop, if the drain for the dishwasher is directly connected, when the home owner puts a plunger on the sink the water is pushed back into the dishwasher.

[relliott]

Ha... good point Jack.
Hence the air gap requirement.