DIY Home Improvement, Remodeling & Repair Forum

DIY Home Improvement, Remodeling & Repair Forum (
-   Plumbing Forum (
-   -   New Dishwasher Install (

tooltime 08-17-2006 04:13 PM

New Dishwasher Install
Hello folks. So this time I want to install a dishwasher. Of course I have googled, but all I seem to find is a typical replacement proceedure.
I want to isntall this dishwasher away from the sink. Running electrical w/ GFI I can do. Branching off the plumbing in the basement should be easy enough for me to do, but need to see if there is anything I am overlooking.
I think the 1/2" pipe and fittings should be pretty darn simple, but I am concerned with the drain mostly.
Any suggestions? Any other concerns I should be looking at?
Should have had this done a cpl weeks ago, but now it's way past crunchtime now :(

Oh, on a side note.. is there a such thing as a sink vent? I remember a pipe coming up out of the kitchen exterior wall while I was in the atic over the spring... is it something I should be concerned about if I relocate the kitchen sink? No idea if it is from the sink/drain inside the wall.. but it does run over to the bathroom in the attic, and from there I think to a vent in the roof.

As always, any and all help is appreciated, Thank You.

glennjanie 08-18-2006 09:50 AM

Hi Tooltime:
Yes, a dishwasher does need an air gap in the drain line to prevent siphoning sewage back into it. An air gap is inexpensive and is mounted on top of the counter. The drain hose is attached to one side of it and a larger hose is connected to the garbage disposal in your sink. Most plumbing codes require that a dishwasher be discharged into a disposal because it will be washing food particles off the dishes (which constitute sewage).
You are correct about the sink vent and yes, it should have a vent reconnected after you move the sink. It sounds like you are going to place the dishwasher away from the sink which is highly unusual. Most folks rinse the dishes before putting them in the dishwasher. If you'll give me more specifics and want my help; I will be glad to help.

skopper 08-18-2006 10:25 AM

Most newer dishwashers do not require an air gap as long as they are installed according to the manufacturers' instuctions.

Hube 08-18-2006 03:55 PM

and I too echo what 'skopper' has said; follow the manufacturers installation guide and you will not need any air gap whatsoever.
Just make sure you have the proper height in the "drain loop", that is the 'key 'to having no siphon effect or any need for an air gap.

Smashed Thumb 08-18-2006 07:26 PM

Yes you can get away with out a vent going out the roof if you need. There are 2 different options. 1 you can do a loop on your drain by putting a tee below the tee for the drain and looping pipe from top of drain tee back to bottom tee. It might drain slow or guggle a little. They also make a item called a pro vent come out of top of drain tee even in wall instal pro vent on top or as high as you can get it and it will suck a litle air to let it drain better. Hope this is of help.

glennjanie 08-19-2006 01:25 PM

Hi Tooltime:
My previous statements are according to the Kentucky Plumbing Code; one of the strictest in the country. I don't think Ohio would have that much less of a code than Kentucky.
Yes, I have heard the thing about a 'high loop' in the dishwasher drain line. My question is, "Have you ever siphoned any gas from your pickup turck for your lawn mower"? I have demonstrated this phenomenon to my plumbing class a couple of times much to their surprise.
I have used a Pro-Vent in the past. It uses a small plate that is spring loaded to pop up to the top of the vent and seal noxious air in the plumbing system while a negative pressure in the system will pull the plate down and allow some air in the system. It works just great; until the spring rusts away leaving the plate down all the time and giving a strong whif of sewer gasses. I'm not trying to be contentious about this; I just want you to know there are dangers lurking in your sewer systme, like botulisim, ptomane poison, and methane gas. Procede with caution.

Square Eye 08-19-2006 02:10 PM

Say 5 different people take the plumber's license exam in different states.
They all proceed to become Masters.
I ask each of them the same question.
I may only have 2 of them agree on an answer.

Plumbing code and building code are to some degree, variable by the area that you are in, and further complicated by the state's own code restrictions.

As long as you guys keep things civil and, even better, friendly, there wil be something for everyone to learn.

The siphoning thing is a valid point, but the garbage disposal connection is well above the dishwasher drain, so it surely won't evacuate all the water from the dishwasher. BUT how much water flows back into the dishwasher after the drain cycle is complete? Is there a check valve in the line to stop the backflow? I have seen nasty stinking water in the bottom of a dishwasher before, does that indicate a plumbing problem?
It seems to me that an air gap should settle the drain quicker, and with less drain pipe, it should return less water into the dishwasher drain....right?

I ain't no plumber, I got questions too!

manhattan42 08-23-2006 10:19 PM

All due respect to Glennjanie, but Kentucky Code has absolutely NO jurisdiction in Ohio or anywhere outside his own state...
That said, why not simply go to what Ohio Plumbing Code states and answer authoritatively?


Section 802.1.6 Domestic Dishwashing Machines.

"The waste line of a domestic dishwashing machine discharging into a kitchen sink tailpiece or food waste grinder shall connect to a deck-mounted air gap OR the waste line rise shall be securely fastened to the underside of the sink rim or counter."

Ohio Plumbing Code allows a deck mounted air-gap OR the waste line rise without an air gap place as close to the underside rim of the sink or counter as possible...

Just like in Pennsylvania and 47 other US states.

All times are GMT -6. The time now is 03:36 PM.