Garbage disposal plumbing

[kactuskid]

Lots of folks nowadays are installing deeper undermount sink bowls and granite counter tops in their remodeling projects. Then they install a disposal and find that the disposal drain is lower than their wall outlet drain. This allows the disposal to sit in a few inches of water and requires it to "pump" water up instead of relying on gravity.

Taking the proper measurements prior to installation can of course avoid this problem, but my question is what are the options to ensure a proper installation other than lowering the wall outlet drain. And are there any working remedies once an installation like this has been installed. I don't think I've seen any GD that are shorter in height to accomidate a situation like this.

As always, thanks

[LazyPup]

Mounting the discharge of a disposal below the waste arm and relying upon the disposal to pump the discharge upwards is not an option. The codes require that the disposal must discharge into a gravity drain.

Normally a kitchen drain waste arm is set at 18" above the finished floor. Even with deep sinks that should provide adequate clearance for s disposal under a deep sink. Where most people encounter a problem is when connecting a disposal to a double sink when one or both sinks are deep sinks. Here again, it is not normally a problem except most people attempt to use a conventional "End Waste" or "Center Waste" kit to make the connection. A conventional waste kit requires the discharge from the disposal to be turned 90 deg downward before attaching to the drain. This results in loosing about 2.5" of vertical clearance.

The proper method is to select a waste kit that is set up for a disposal. When attaching a "Disposal waste kit" the preformed 90 deg bend that comes packed with the disposal is not used. The Disposal waste kits have a cross tube that has a flat flanged end that connected directly to the disposal outlet and runs the cross tube to the TEE at the same height as the Disposal drain port. This will allow another 2.5" tp 4" of vertical clearance above the trap.

Raising the Tee section will then allow raising the P-trap to the appropriate height.

[kactuskid]

Wow, great explanation of how to make this work. Thanks so much for your time, always appreciated.

[Max]

Our garbage disposal has recently developed a slowness too, it never used to run slowly. Switching on the disposal forces the water away with no problems though. I used some foaming plumber (the kind recommended for disposals) and left it for an hour then flushed it away. I'm not sure if that did anything or not, it appeared to alleviate the problem a little bit. I did a lot of reading online but it's still not clear to me where the problem might be. Any ideas? We did fit a deeper sink last year but the problem did not manifest itself at that time, this is a relatively recent thing.

Here's a pic of the configuration under the sink:


Cheers, Max

[LazyPup]

Good Morning Max..

You stated that your disposal is running slow but you also referred to having used a chemical drain opener so I presume you mean the drain is running slow, rather than the actual RPM of the disposal motor.

While there are some rather harsh chemical cleaners that we occassionally use in the trade, I think you will find that most trained plumbers are rather vehemently opposed to the use of chemical drain cleaners for a number of reasons.

1. Chemical drain cleaners are seldom effective at truely alleviating the problem. In most instances as soon as they open a passage through the clog large enough for the liquids to flow, the chemical goes down the drain leaving the majority of the clog stick stuck to the pipe walls where it will quickly form another clog.

2. If the chemical drain cleaner can not open a passage you are then left with a sink full of very dangerous liquid that you must deal with before you can get the traps or cleanouts open to snake the line. Do not take this caution lightly, many drain openers are Akali or sulphuric acid base and in concentrated form they can cause 2nd and 3rd degree chemical bunrs on your skin, instant blindness if splashed in your eye, or will litterally cause your clothing to crumble and fall off your body leaving you in a rather delicate position, especially when in a customers home.

3. Harsh chemical drain cleaners can also cause severe damage to disposal housings as well as cause stains and discoloration on the chrome drain baskets or the finish of porcelan, fiberglass or synthetic sink or tub materials.

4. If chemical drain cleaners are splashed on cabinets or spilled on the floor they can cause severe damage to the wood finish, permanent stains in ceramic tile grout and may lift vinyl tiles.

5. Under some rare circumstances chemical drain cleaners can react very harshly with the materials causing the clog and will form tremendios heat or pressure to develope in the pipes. Although it is extremely rare, none the less, there have been many instances of a drain pipe literally blowing off from the pressure and spewing the chemical all over the kitchen or bath area.

Perhaps one of the cheapest investments a homeowner can make is a 3/8" x 15' wire drain snake. The look like a long screen door spring with a little hook formed on one end and a short lenth of tubing with a lockdown screw attached. You simply open a trap or cleanout, insert the hooked end of the spring into the drain and push it in till you hit the clog. When you hit the clog you can try jamming the snake in or out a few times and if that don't work slide the tube up close to where the snake enters the pipe, tighten the lockscrew then use the bent tube as leverage to rotate the snake a few turns. In most cases that with break the clog loose from the pipe wall and clear the drain. Inexpensive wire drain snakes can be found in all hardware stores for about $6 to $10 and under normal circumstances it will last for years. (Here is a tip, the snakes often come packed in a plastic bag. After use, wipe the gook off the wire with a rag, then roll the snake up in a coil and tie with a piece of wire, but do not store it in a plastic bag. Simply hang it in the garage, shed, basement or utility room where it can air dry. Leaving it sealed in a bag will cause it to rust through)

Here is another tip, about once a week run a few ice cubes through your disposal. Grinding ice cubes will help clean the buildup debris off the cutters and keep the disposal working clean and free.

I have examined your photo and it looks like you have a very good installation. All of your drain fittings are glued PVC with the exception of the "Trap Adapter" where the disposal output connnects. Fortunately the installers left you numerous options for snaking the line. I have noted both the cleanout caps which can be unscrewed to permit running a drain snake in the line.

You can also access the line by removing the two drain flange mount screws on the disposal body, then loosen the trap adapter and the 90 deg elbow can be pulled off the disposal leaving access both to the cutters in the disposal and the top of the trap for snaking the line.

The only thing on your installation that you might want to change is the postition of the dishwasher drain line. It should run up to a high loop inside the cabinet, which your does, then it should loop just a bit below the disposal input port and back up for final connection to the disposal. The purpose of the loops is to create a natural air trap in the dishwasher drain line to prevent any waste from backflowing back into the dishwasher which could result in contaminating your dishwasher.

[Max]

Hi LP,

Thanks for the information, a pipe snake will be picked up in due course (maybe tomorrow).

I shouldn't have said the disposal is slow, I should have said the DRAIN is slow but switching on the disposal pumps the water away. One test I am thinking of doing is disconnecting the dishwasher drain and running water through the sinkto see how fast the water drains. If it drains quickly then I know there is a clog in the plumbing / pipes.

How are cleanout traps secured? I know they thread in place but do I need to put something in there as well to make the seal water tight?

Also, thanks for the tips on the drain cleaners, I will stay away from them in future. I guess they are an easy product for anybody to use which is why they sell even though they seem to be potentially very dangerous. I know they have warning all over them but I'll bet most folks don't read them and just think, "as long as I don't splash it around I'll be fine".
Cheers, Max

[LazyPup]

Cleanout plugs have an NPT (National Pipe Taper) thread, which means the diameter of the male thread gets larger as you tighten it into the female fitting deeper. While normally not required to effect a good seal, I would recommend applying a few wraps of PTFE (Teflon Tape), in this case as a thread lubicant as well as sealant. This will aid in preventing the threads from getting stuck in the event you need to open the cleanouts again in future.

Before you open the cleanout cap on the bottom of the trap be sure to put a catch pan under the trap to catch the water in the trap.

In regards to removing the dishwasher line to check the flow. Once you disconnect the line you will need to find a way to plug the dishwasher input port also. A simpler method would be to bend a kink in the dishwasher line and hold it with your hand while you run the water. That will prevent the possibility of water backflowing to the dishwasher.

[Max]

Thanks again, LazyPup.

I made another booboo, this time in my 2nd post. I didn't mean to say dishwasher, I meant to say disposal. Wow, me and the typos, huh!

What I attempted to say was I will disconnect the pipe from the disposal and run water through the sink. If the water flows out of he disposal at a good rate then I know there is no blackage in the unit. I have an old cat litter box under the sink to catch the water. Chances are, I think, that if there is a blackage I will find it in the trap.

[LazyPup]

If you were to disconnect the discharge line from the disposal and look in the port you will see it is nearly wide open directly to the edge of the cutter wheel Unless you have attempted to pour discarded plaster of paris or cement in the disposal it is highly unlikely that the clog could be in the disposal itself.

I think if you open the cleanout port on the underside of the trap you will most likely find the clog right there, if not, it will probably be near the point where the horizontal waste arm enters the wall.

[Max]

OK, here's what has happened. I bought a pipe snake from Sears. When I got home I disconnected the disposal unit and ran water through and the water came out very strong so that ruled out the disposal. I tried shoving the pipe snake down into the trap but it got stuck right away, it didn't go around the u-bend. Using a flashlight and a mirror I could see into the u-bend and it was crystal clear. I took off the bottom cleanout plug and confirmed that. I then took off the top cleanout plug and ran water through the sink. Using the mirror and flashlight again I looked into the horizontal pipe (from above) and I could see the water flowing through the pipe. The force wasn't strong enough to push the water out of the cleanout hole. I ran a couple of partial sink-loads of water through the pipe and then heard a weird glug sound from the sink and ever since then the water appears to be flowing fine. Is it possible that opening up the top cleanout plug and running water through the pipe could clear out a clog? That's what it sounded like. Weird.

[LazyPup]

There is an infinite number of things that could have accounted for why the drain mysteriously opened up. The only firm fact in drain cleaning is that you will seldom see whatever it was tha caused the original problem.

[Max]

Thanks for the tips 'n tricks.