Trapped dishwasher drain line OK?

[Kenton H. Shepard, CMI]

The copper pipe connecting to the trap that connects to the cast iron waste is the drain line from the dishwasher above.

Since potential contamination from siphoning is the problem with the dishwasher drain line, this looks to me like it would be OK, but it also doesn't really seem right.

It wouldn't be installed according the manufacturer's instructions, but what exactly is the defect? Dissimilar metals in contact?

[Bob Elliott]

How is the copper line being connected to the top of that trap?


Is there an open gap or is it some how sealed?

[Bob Elliott]

Trying to find wordage but if the drain does not have a high loop too than I think the water will just drop out of the dishwasher with a siphon like effect.

Some brands have a loop built in , but some do not.

Where is the plumbing vent?

[Kenton H. Shepard, CMI]

Originally Posted by belliott

Trying to find wordage but if the drain does not have a high loop too than I think the water will just drop out of the dishwasher with a siphon like effect.

Some brands have a loop built in , but some do not.

Where is the plumbing vent?

It's OK if water drops OUT of the dishwasher, the siphoning problem is with dirty water being siphoned back into the dishwasher from the drain line. Not likely to happen here.

I didn't get a good look at the connection since I knew I was going to recommend correction for dissimilar metals and non-conforming installation. I wish now that I had jsut to satisfy our curiosity.

[Brian E. Kelly]

Looks like the copper makes a Hi Loop to me Kenton before it goes into trap. If an Air gap is not required a Hi Loop is acceptable.

You might be able to defect out the copper to trap connection as I can not tell from the photo how exactly that is made.

[Bob Elliott]

Kenton it is not OK for the water to completly drain out is what I am saying.
The seals will dry up.
The reverse loop has two reasons.
Cross contamination is one, and two is so the seals still have water in them .
C apish!

(think running a spa tub that has no water)

[Kenton H. Shepard, CMI]

Originally Posted by bkelly2

Looks like the copper makes a Hi Loop to me Kenton before it goes into trap. If an Air gap is not required a Hi Loop is acceptable.

You might be able to defect out the copper to trap connection as I can not tell from the photo how exactly that is made.

You're right Brian, it does. Man! I must have looked right at it. Haven't sent the report yet though, thanks!

I've never seen a production adapter for this situation so I'm thinking that it's something the plumber invented.

I'm going back up to retrieve the radon monitor. I'll get a photo.

[Bob Elliott]

Originally Posted by kshepard

You're right Brian, it does. Man! I must have looked right at it. Haven't sent the report yet though, thanks!

I've never seen a production adapter for this situation so I'm thinking that it's something the plumber invented.

I'm going back up to retrieve the radon monitor. I'll get a photo.

Do you know the Dishwasher make and model?

[Kenton H. Shepard, CMI]

Originally Posted by belliott

Do you know the Dishwasher make and model?

No, but it's an older model, Bob. I can find out tomorrow. What would I do with that information? Is there an easy way to find out if it has an integral anti-siphon device?

[Brian E. Kelly]

Originally Posted by kshepard

No, but it's an older model, Bob. I can find out tomorrow. What would I do with that information? Is there an easy way to find out if it has an integral anti-siphon device?

Intergal anti siphon is to protect the city water from you. Hi loop (Air gap) is to protect you from yourself.

[Kenton H. Shepard, CMI]

I thought the integral was an air gap device built into the back of the cabinet that prevented dirty water from siphoning back into the cabinet interior and contaminating the contents.

[Bob Elliott]

Originally Posted by bkelly2

Looks like the copper makes a Hi Loop to me Kenton before it goes into trap. If an Air gap is not required a Hi Loop is acceptable.

You might be able to defect out the copper to trap connection as I can not tell from the photo how exactly that is made.

Darn you Brian
I just saw that as I dismissed it as another line (***=uming the DW was straight above.

Still may be in the wrong place.

Kenton you can get mnfr instruction and find out if it is a high loop maybe.
Since that could end up time consuming ,it is much less intensive to call for a high loop rather than look up every unit you come across.

There are a few appliance look up sites but it could end up like when you need to find a Manuel for an 30 year old Furnace.

(edit) I can't believe they edited A-s uming

[dbolduc]

There is not a vertical drop with the installed 'T' in the copper DWV , more apt to have a problem there with waste plugging up the trap. The 'T' should have been turned up 90*, maybe something else used it previously and they decided to use the existing system as is.

I would question whether the manufacturer would allow an additional length of small diameter run, especially copper pipe. Next, I expect that the manufacturer requires their drain line to be installed to a DWV which the copper tubing is absolutely not. There is also another fitting on the copper on the upper right side of the pic which may further reduce flow by increasing restriction. There is probably a good amount of corrosion going on inside the copper pipe .

It just ain't right, IMHO.

http://www.copper.org/applications/p...th_table1.html

[Patrick Bolliger]

P trap NOT designed for that application! Incorrect use of piping. What about materials fellas? I see copper P traps but mixing a common sink P trap (possible) corrosion problems and sealing issues. This is a quick fix deal without professional design in mind. What happens with the pipe leaks regardless of the Dishwasher connection...

[Kenton H. Shepard, CMI]

Originally Posted by belliott

Darn you Brian
I just saw that as I dismissed it as another line (***=uming the DW was straight above.

Still may be in the wrong place.

Kenton you can get mnfr instruction and find out if it is a high loop maybe.
Since that could end up time consuming ,it is much less intensive to call for a high loop rather than look up every unit you come across.

There are a few appliance look up sites but it could end up like when you need to find a Manuel for an 30 year old Furnace.

(edit) I can't believe they edited A-s uming

I went back and looked. The line on the right is another line. It's the supply line for the dishwasher, so there's no high loop, but the siphon is not likely to be strong enough to pull water straight up, in fact, I don't think there will be any standing wagter in that vertical drain pipe at all. The connection to the P-trap was actually pretty good, but the whole thing is jury-rigged.
I just wrote it up as an incorrect installation and the buyer can have a tech figure it out if it bothers him enough. It's not really right, but I think it functions OK.
If it fails, I guess the failure would be the dissimilar metals in contact causing slow, long-term galvanic corrosion. Since the corrosion only happens when the metals are electrically connected with moisture, I think it'll last a while.