Thread: Open trap downstream of primary trap

Came across an open trap that is connected to the drain line after the sink trap. They have a dehumidifier hose draining into this trap. It seems that sewer gas could could enter from the open trap and that the primary sink trap is therefore not functioning as intended. Am I right on this one?

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Looks like both traps go into a wye fitting,

As such, each trap would operate independently ... until there was a back up in the sink trap, which would cause the other trap to overflow - would not be pretty.

Also, the drain line into the other trap should have an air gap and not go down into the trap as shown.

I can see too many risky things happening that I would not want that configuration - raise the drain trap riser to above the flood level rim of the sink and it would be less prone to problems.

I'm waiting to be convinced otherwise.

As such, each trap would operate independently

Yes, each trap operates independent of the other

... until there was a back up in the sink trap, which would cause the other trap to overflow ...

The other trap would overflow if it became blocked or if the drain line became blocked, not if the trap on the sink was blocked.

Originally Posted by Jerry Peck

As such, each trap would operate independently ... until there was a back up in the sink trap, which would cause the other trap to overflow - would not be pretty.

Originally Posted by Rick Cantrell

The other trap would overflow if it became blocked or if the drain line became blocked, not if the trap on the sink was blocked.

(slaps hand to forehead) DUH! Jeez, Jerry, did you actually even read what you wrote? (Apparently not!)

Love plumbing optical illusions.
Thanks!

Give the installer credit.
They color coded the independent water line traps.

I think it's a safety thing, you know, to advise technicians working downstream the main P-trap of possible sewer gas or flooding.

You never know, it could happen.

Originally Posted by sidney alstad

Came across an open trap that is connected to the drain line after the sink trap. They have a dehumidifier hose draining into this trap.

Originally Posted by Jerry Peck

Looks like both traps go into a wye fitting,

Also, the drain line into the other trap should have an air gap and not go down into the trap as shown.

I'm waiting to be convinced otherwise.

Discharge (drain line) from a dehumidifier is only required to have an air break, not an air gap.
There is no cross connection to potable water.

Why not change the tailpiece from the bowl to a 1.5" branch such as for a dishwasher and dump the condensate into it? You keep it as one P trap. Use the left branch of the wye as a cleanout.

Yes, being below the flood rim of the bowl is asking for trouble.

Originally Posted by Bob Harper

Why not change the tailpiece from the bowl to a 1.5" branch such as for a dishwasher and dump the condensate into it? You keep it as one P trap. Use the left branch of the wye as a cleanout.

Yes, being below the flood rim of the bowl is asking for trouble.

I concur, a sink tail waste refit is required.
Single Spigot Tail Sink Waste, P Trap & clean out would be more convenient. They would recoup some elbow room under the sink.
Single spigot tail piece and P trap.JPG

Rick, from this angle I personally see no use for the Y.
Can you elaborate on the setup please.

Note, might be an idea to recommendation replacing the PB/PEX speedways for rubber tube & stainless braid.
Not a big fan of brass compression fittings on plastic.
That type of setup tends to leak or fail when you are away for an extended time.

Originally Posted by ROBERT YOUNG

I concur, a sink tail waste refit is required.


Rick, from this angle I personally see no use for the Y.
Can you elaborate on the setup please.
.

Originally Posted by Bob Harper

Why not change the tailpiece from the bowl to a 1.5" branch such as for a dishwasher and dump the condensate into it? You keep it as one P trap. Use the left branch of the wye as a cleanout.

Yes, being below the flood rim of the bowl is asking for trouble.

Yes, it could be changed and may be more convenient, but why?
No, it is not required to empty into a tailpiece.
Also, we (HI's) should avoid designing the repair.
Finally, as shown, I do not see a violation. Maybe a little awkward, but it does the job.

Rick, wrong is wrong.

It is suspect to flooding, violation or not.
Below the primary trap.
Water does not flow upstream.
The trap is gravitational not mechanical.
Look at the image.


Just wondering, when is using an example on a Mb designing the repair?

Originally Posted by ROBERT YOUNG

Rick, wrong is wrong.

It is suspect to flooding, violation or not.
Below the primary trap.
Water does not flow upstream.
The trap is gravitational not mechanical.
Look at the image.


Just wondering, when is using an example on a Mb designing the repair?

The primary trap for the condensate drain has nothing to do with the overflow rim on the sink.
They are two separate traps.

I saw that Jerry was looking at this thread a moment ago.
What say you Jerry?

Originally Posted by Rick Cantrell

The primary trap for the condensate drain has nothing to do with the overflow rim on the sink.
They are two separate traps.

Why ask Jerry.
You are or were a teacher.

Is it a indirect drain line?
I asked previously.

Double trapping is not compliant. Hydraulics thingy.

Awaiting a reply.

Question, If the DWV gets blocked downstream, past the primary sink P, the backup can be as much as that basin contained by volume unless frozen when returned, LOL
So the basin, sink, wll hold its own liquid I presume?

Rick, what about the non-compliant trap & basin, off the Y?
Ops, none. No basin.
It will flood the sink water.

Sorry for the edits.

Originally Posted by ROBERT YOUNG

Question, If the DWV gets blocked downstream, past the primary sink P, the backup can be as much as that basin contained by volume unless frozen when returned, LOL
So the basin, sink, wll hold its own liquid I presume?

Rick, what about the non-compliant trap & basin, off the Y?
Ops, none. No basin.
It will flood the sink water.

Sorry for the edits.

Sorry Robert I don't follow what you are trying to say.

Originally Posted by ROBERT YOUNG

Why ask Jerry.
You are or were a teacher.

Is it a indirect drain line?
I asked previously.

Double trapping is not compliant. Hydraulics thingy.

Awaiting a reply.

I don't see a double trap.


Tell me what is/ are the violations you see.

So sorry Rick.
My narrative confuses Confucius.
Confucius Say
The inventor of shag carpet made a big pile.

IRC
P3201.6 Number of fixtures per trap.
Each plumbing fixture shall be "separately trapped: by a water seal trap.
The vertical distance from the fixture outlet to the trap weir "shall not exceed 24 inches (610 mm) and the horizontal distance shall not exceed 30 inches (762 mm) measured from the center line of the fixture outlet to the centerline of the inlet of the trap. The height of a clothes washer standpipe above a trap shall conform to Section P2706.2.
"Fixtures shall not be double trapped."
Chapter 32 - Traps

P3201.3 Trap setting and protection.
Trap seals shall be protected from siphonage, aspiration or back pressure by an approved system of venting (see Section P3101).



IPC. 1002.1 IRC. (2) P3201.6 Exc. 2
Combination plumbing fixture "can share a trap" as long as one compartment is not more than 6" deeper than the other compartment and compartment outlets are 30" or less apart.

http://www.iccsafe.org/wp-content/up...tral/9211S.pdf

Sorry for the edit. I thought I included Trap setting and protection.

What is pictured is two separate traps, not a double trap.
There is one trap serving the sink, and a separate trap for the condensate drain line.
Nothing wrong with that.
Do you see something I don't see?

Originally Posted by Rick Cantrell

What is pictured is two separate traps, not a double trap.
There is one trap serving the sink, and a separate trap for the condensate drain line.
Nothing wrong with that.
Do you see something I don't see?

P3201.3 Trap setting and protection.

- - - Updated - - -

All the best Rick.
Flogging a dead horse.

Originally Posted by ROBERT YOUNG

P3201.3 Trap setting and protection.

- - - Updated - - -

All the best Rick.
Flogging a dead horse.

????

What does this:
- P3201.3 Trap setting and protection.
- - Traps shall be set level with respect to their water seals and shall be protected from freezing. Trap seals shall be protected from siphonage, aspiration or back pressure by an approved system of venting (see Section P3101).

Have to do with the original photo or the discussion?

There are two traps in the original photo, nothing is "double trapped".

Originally Posted by Jerry Peck

????

What does this:
- P3201.3 Trap setting and protection.
- - Traps shall be set level with respect to their water seals and shall be protected from freezing. Trap seals shall be protected from siphonage, aspiration or back pressure by an approved system of venting (see Section P3101).

Have to do with the original photo or the discussion?

There are two traps in the original photo, nothing is "double trapped".

I stand corrected.
Gees Louise...Thanks.
Sorry Rick.

P3201.3 Trap setting and protection. Trap seals shall be protected from "siphonage", aspiration or back pressure by an approved system of venting