Thread: Sink drain drain line configuration

This drain is at a laundry sink in a 65 yr old home. I think an artist got ahold of the plumber. It is configured like the old 'S-trap' style, no longer approved, and it has a mobile home style mechanical vent.
Any thoughts are welcome. I called for a licensed plumber to r/r.

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Originally Posted by Mark Ryan

This drain is at a laundry sink in a 65 yr old home. I think an artist got ahold of the plumber. It is configured like the old 'S-trap' style, no longer approved, and it has a mobile home style mechanical vent.
Any thoughts are welcome. I called for a licensed plumber to r/r.

The line coming in from the right is the washing machine drain line.

I do not see a S trap anywhere?

A: There is a P trap.
B: A horizontal DWV entering a vertical DWV .
C: An (AAV) air admittance valve atop the a vertical DWV.

What appliance if any is to the the right of that basin in the photo?

S-trap, appears to be enough room there to put a proper p-trap.
Also AAV should be above flood rim (vent should be on top of counter).

No "S" trap is present (because it ties into a vertical vent with a sanitary tee).

No AAV is present (there is a mechanical vent installed).

The height for the AAV (when installed, and the height of the mechanical vent - which is not permitted there) only needs to be 4 inches above the weir of the trap.

Originally Posted by ROBERT YOUNG

I do not see a S trap anywhere?

A: There is a P trap.
B: A horizontal DWV entering a vertical DWV .
C: An (AAV) air admittance valve atop the a vertical DWV.

What appliance if any is to the the right of that basin in the photo?

The drain line from the right is the washing machine

Originally Posted by Mark Ryan

The drain line from the right is the washing machine

That is why the AAV was installed.
Let me look at the image again.

Originally Posted by ROBERT YOUNG

That is why the AAV was installed.
Let me look at the image again.

Originally Posted by Mark Ryan

Another view of drain

You're the best.
From my understanding, limited as it may be, no Y.

How wide is the pipe? Does not look 2".

Originally Posted by ROBERT YOUNG

How wide is the pipe? Does not look 2".

2" I believe

Originally Posted by ROBERT YOUNG

From my understanding, limited as it may be, no Y.

That's not a 'Y', that's a 'combination wye and eight bend', it is allowed to be used for changes in direction as follows: horizontal to vertical (as shown in the photo); vertical to horizontal; horizontal to horizontal. See Table P3005.1 in the IRC.

Mechanical vents were only permitted in manufacturedifferent houses. For quite a few years they have only been approved for use in RVs. So, regardless of the piping configuration it is wrong.

I thought I read were AAV's can be used under certain circumstances.
I was waiting o post th AAV.
I will look to find the article when I find some time.

NPC
A-2.2.10.16.
To limit the probability that the installation "of inappropriate air admittance valves" or of valves that do not conform to the appropriate standard will lead to the entry of sewer gases into occupied space, which could lead to negative effects on indoor air quality, which could lead to harm to persons.

Originally Posted by ROBERT YOUNG

I thought I read were AAV's can be used under certain circumstances.
I was waiting o post th AAV.
I will look to find the article when I find some time.

AAVs are still not (to my knowledge) permitted to be used in Illinois.

I'm not sure if California has limitations on their use.

Other than those two states, I think AAVs are permitted to be used.

There are limitations, restrictions, and requirements which must be met ... but every product has limitations, requirements, and restrictions to meet.

AAVs can provide venting in areas where it may otherwise be difficult to provide venting.

One key point, though, is that those black vents are not AAVs - they are "mechanical vents" which use springs for operation.

An AAV uses the differences in air pressure for operation.

Originally Posted by Jerry Peck

AAVs are still not (to my knowledge) permitted to be used in Illinois.

I'm not sure if California has limitations on their use.

Other than those two states, I think AAVs are permitted to be used.

There are limitations, restrictions, and requirements which must be met ... but every product has limitations, requirements, and restrictions to meet.

AAVs can provide venting in areas where it may otherwise be difficult to provide venting.

One key point, though, is that those black vents are not AAVs - they are "mechanical vents" which use springs for operation.

An AAV uses the differences in air pressure for operation.

Good points.

Originally Posted by ROBERT YOUNG

I thought I read were AAV's can be used under certain circumstances.
I was waiting o post th AAV.
I will look to find the article when I find some time.

NPC
A-2.2.10.16.
To limit the probability that the installation "of inappropriate air admittance valves" or of valves that do not conform to the appropriate standard will lead to the entry of sewer gases into occupied space, which could lead to negative effects on indoor air quality, which could lead to harm to persons.

AAV valves are permitted in the IRC. I don't know Canadian codes. That vent valve is a mechanical vent, which is not permitted. If you look at ads for them you will see that they have a NSF 41 approval or something like that. That approval is presently only for RVs. It used to be for manufactured houses also. Some people refer to these valves as AAVs, but they are not.

True AAV's are allowed in Canada. They are a must in a modern kitchen with the sink(s) in an island. And they go in under the usually granite counter top.

I posted a pic a few years back of an island drain vent built from loops of cast iron and a half dozen Fernco connectors. High-rise condo. The AAV eliminates all that pipe.

That pipe is 1 1/2" diam. The drop tube is 1 1/4". That long sweep pointing down in the clothes washer drain is wrong because air can only get in below the bend.

BASED ON THE ONTARIO BUILDING CODE 2012, O. REG. 332/12
7.5.9.2.

7.5.9.2. Air Admittance Valves
(1) Air admittance valves shall only be used to vent,
(a) fixtures in buildings undergoing renovation, and
(b) installations where connection to a vent may not be practical.
(2) The air admittance valves shall be located,
(a) above the flood level rim of the fixture it serves,
(b) within the maximum developed length permitted for the vent,
(c) not less than 150 mm above insulation materials, and
(d) installed in a location not subject to back pressure.
(3) Air admittance valves shall,
(a) only vent fixtures located on the same storey, and
(b) be connected to the horizontal fixture drain.

7.5.9.3. Installation Conditions
(1) Air admittance valves shall not be installed in supply or return air plenums, or in locations where they may be exposed to freezing temperatures.
(2) Air admittance valves shall be installed in accordance with the manufacturer’s installation instructions.
(3) Air admittance valves shall be rated for the size of vent pipe to which they are connected.
(4) Installed air admittance valves shall be,
(a) accessible, and
(b) located in a space that allows air to enter the valve.
(5) Every drainage system shall have one vent that terminates to open air in conformance with Sentence 7.5.6.2.(1).

Waste Plumbing and the Importance of Venting

Originally Posted by Mark Reinmiller

AAV valves are permitted in the IRC. I don't know Canadian codes. That vent valve is a mechanical vent, which is not permitted. If you look at ads for them you will see that they have a NSF 41 approval or something like that. That approval is presently only for RVs. It used to be for manufactured houses also. Some people refer to these valves as AAVs, but they are not.

.......mechanical vents may still be used in manufactured (HUD Code) homes..........Greg

Hello Raymond. Are you saying that you call for the AAV to be mounted above the counter top?

It is simply not done that way here. Maybe water drains uphill in Ontario? No, those rules are archaic.

JP, thanks for the clarification and you are right, standpipe lets air in.

Originally Posted by John Kogel

That pipe is 1 1/2" diam. The drop tube is 1 1/4". That long sweep pointing down in the clothes washer drain is wrong because air can only get in below the bend.

The drain from the right, from a standpipe for a clothes washing machine, is 2" and goes into a combination wye and eight bend (which is allowed for that use because: a) the fitting itself is allowed for that use; b) the vent for a clothes washer standpipe is the standpipe itself, the hose going into the standpipe from the clothes washer should never ... never ... fill the standpipe and seal it off).

The 2" combination wye and eight bend go into a 2" pipe - at the top of the 2" pipe is a 2" x 1-1/2" reducer bushing, and into that reducer bushing is a 1-1/2" pipe.

The piping from there up is 1-1/2", with the exception of the 1-1/4" tailpiece from the sink.

Looks funky, but right, to me. It looks funky because the combination wye and eight bend is usually in the wall and not seen, usually what is seen is the trap arm sticking out of the wall going to the trap. I suspect there are many places where this is normal and typical because the plumbing is not necessarily "in the wall" as I usually find. I know that "European Cabinets" (as I've heard them referred to) have the bottom of the cabinets short from the wall to allow for plumbing which comes up out of the floor outside the wall.

Originally Posted by John Kogel

Hello Raymond. Are you saying that you call for the AAV to be mounted above the counter top?

It is simply not done that way anymore, and the rule you posted is wrong or out of date.

John,

Remember, Raymond presented what Quebec uses ... and Quebec still insists on speaking French, unlike the rest of the Canada and those 'South of the border' down here in the US of A.

Originally Posted by Jerry Peck

John,

Remember, Raymond presented what Quebec uses ... and Quebec still insists on speaking French, unlike the rest of the Canada and those 'South of the border' down here in the US of A.

Well actually, the provincial government insists on a 50/50 approach to marketing by it's residents as the residents speak the native languages they are accustomed to.

As well, Raymond represents Ontario, that has no official language and doubled it population and financial growth at its neighbor's expense.

Money flows like water, downstream and is affected by the path of least resistance.

John

I am not saying it, the building code is dictating the location.
(a) above the flood level rim of the fixture it serves,
and under installation - (2) Air admittance valves shall be installed in accordance with the manufacturer’s installation instructions.

And Jerry this is the Ontario code I published and not the Quebec code.

Originally Posted by Raymond Wand

And Jerry this is the Ontario code I published and not the Quebec code.

Yep, my error, I looked at the link before clicking on it and thought I saw QBC instead of OBC, and didn't look further to see which it was, that's why I mentioned French to Robert as he is in Quebec and I thought you were showing the Quebec building code to Robert ... I need to look closer (or get new glasses ... actually, I need to get new classes anyway as my eyes have changed since I got these a couple of years ago - just have not made the time to get new ones because it is such a hassle).

Originally Posted by Gregory Booth

.......mechanical vents may still be used in manufactured (HUD Code) homes..........Greg

Myers understanding is that the HUD code references the NSF 41 ? Standard but that standard no longer approved mechanical vents for manufactured houses. I have documentation regarding this.

Originally Posted by Mark Reinmiller

Myers understanding is that the HUD code references the NSF 41 ? Standard but that standard no longer approved mechanical vents for manufactured houses. I have documentation regarding this.

NSF-41 does not relate to vents, it is for non-liquid systems, composting toilets: NSF/ANSI 41: Non-Liquid Systems - NSF International

"SF/ANSI Standard 41 certifies composting toilets and similar treatment systems that do not use a liquid saturated media as a primary means of storing or treating human excreta or human excreta mixed with other organic household materials."

From the HUD 24 CFR Part 3280 - MANUFACTURED HOME CONSTRUCTION AND SAFETY STANDARDS: https://www.law.cornell.edu/cfr/text/24/part-3280

24 CFR Part 3280, Subpart G - Plumbing Systems: https://www.law.cornell.edu/cfr/text...3280/subpart-G

24 CFR 3280.611 - Vents and venting: https://www.law.cornell.edu/cfr/text/24/3280.611
- (d) Mechanical Vents. Where mechanical vents are used as a secondary vent system for plumbing fixtures that are protected by traps, the mechanical vents must comply with paragraphs (d)(1) or (2) of this section. - - (1) Spring-operated mechanical (anti-siphon) vents must comply with the following:
- - - (i) No more than two fixtures individually protected by the spring-operated mechanical vent may be drained by a common 1 1/2 inch diameter drain.
- - - (ii) The drain size for three or more fixtures individually protected by a spring-operated mechanical vent must be at least 2 inches in diameter.
- - - (iii) Spring-operated mechanical vents are restricted to venting fixtures with 1 1/2 inch traps.
- - - (iv) A spring-operated mechanical vent must be installed in a location that allows a free flow of air and is accessible for inspection, maintenance, and replacement. The sealing function must be at least 6 inches above the top of the trap arm.
- - - (v) Materials for the spring-operated mechanical vents must be as follows:
- - - - (A) Cap and housing must be listed acrylonitrile-butadiene-styrene, DWV grade;
- - - - (B) Stem must be DWV grade nylon or acetal;
- - - - (C) Spring must be stainless steel wire, Type 302; and
- - - - (D) Sealing disc must be either:
- - - - - (1) Neoprene, conforming to CISPI-HSN-85, Specification for Neoprene Rubber Gaskets for HUB and Spigot Cast Iron Soil Pipe and Fittings (incorporated by reference, see § 3280.4), and to ASTM C564-97, Standard Specification for Rubber Gaskets for Cast Iron Soil Pipe and Fittings (incorporated by reference, see § 3280.4); or
- - - - - (2) Other material, conforming to ASTM C920-02, Standard Specification for Elastomeric Joint Sealants (incorporated by reference, see § 3280.4), and to ASTM D4635-01, Standard Specification for Polyethylene Films Made from Low-Density Polyethylene for General Use and Packaging Applications (incorporated by reference, see § 3280.4).
- - (2) Gravity-operated mechanical (air admittance valves) vents must comply with the following:
- - - (i) Where installed to vent any fixture, the drain system must have a minimum 1 1/2 inch diameter vent that terminates outside the manufactured home.
- - - (ii) Where gravity-operated mechanical vent devices terminate in the attic cavity, the following requirements must be met:
- - - - (A) The attic cavity must be accessible;
- - - - (B) The sealing device must be installed a minimum of 6 inches above the insulation materials; and
- - - - (C) The attic must be vented in accordance with § 3280.504(c)(1)(i);
- - (3) Mechanical vents must be installed in accordance with the vent manufacturer's instructions.

24 CFR 3280.604 - Materials: https://www.law.cornell.edu/cfr/text/24/3280.604
- Plumbing System Components for Manufactured Homes and Recreational Vehicles - ANSI/NSF 24-1988. (This is the closest thing I saw which might include mechanical vents and AAVs, I didn't find a specific listing for them.)

Originally Posted by Jerry Peck

From the HUD 24 CFR Part 3280 - MANUFACTURED HOME CONSTRUCTION AND SAFETY STANDARDS: https://www.law.cornell.edu/cfr/text/24/part-3280

24 CFR Part 3280, Subpart G - Plumbing Systems: https://www.law.cornell.edu/cfr/text...3280/subpart-G

24 CFR 3280.611 - Vents and venting: https://www.law.cornell.edu/cfr/text/24/3280.611
- (d) Mechanical Vents. Where mechanical vents are used as a secondary vent system for plumbing fixtures that are protected by traps, the mechanical vents must comply with paragraphs (d)(1) or (2) of this section. - - (1) Spring-operated mechanical (anti-siphon) vents must comply with the following:
- - - (i) No more than two fixtures individually protected by the spring-operated mechanical vent may be drained by a common 1 1/2 inch diameter drain.
- - - (ii) The drain size for three or more fixtures individually protected by a spring-operated mechanical vent must be at least 2 inches in diameter.
- - - (iii) Spring-operated mechanical vents are restricted to venting fixtures with 1 1/2 inch traps.
- - - (iv) A spring-operated mechanical vent must be installed in a location that allows a free flow of air and is accessible for inspection, maintenance, and replacement. The sealing function must be at least 6 inches above the top of the trap arm.
- - - (v) Materials for the spring-operated mechanical vents must be as follows:
- - - - (A) Cap and housing must be listed acrylonitrile-butadiene-styrene, DWV grade;
- - - - (B) Stem must be DWV grade nylon or acetal;
- - - - (C) Spring must be stainless steel wire, Type 302; and
- - - - (D) Sealing disc must be either:
- - - - - (1) Neoprene, conforming to CISPI-HSN-85, Specification for Neoprene Rubber Gaskets for HUB and Spigot Cast Iron Soil Pipe and Fittings (incorporated by reference, see § 3280.4), and to ASTM C564-97, Standard Specification for Rubber Gaskets for Cast Iron Soil Pipe and Fittings (incorporated by reference, see § 3280.4); or
- - - - - (2) Other material, conforming to ASTM C920-02, Standard Specification for Elastomeric Joint Sealants (incorporated by reference, see § 3280.4), and to ASTM D4635-01, Standard Specification for Polyethylene Films Made from Low-Density Polyethylene for General Use and Packaging Applications (incorporated by reference, see § 3280.4).
- - (2) Gravity-operated mechanical (air admittance valves) vents must comply with the following:
- - - (i) Where installed to vent any fixture, the drain system must have a minimum 1 1/2 inch diameter vent that terminates outside the manufactured home.
- - - (ii) Where gravity-operated mechanical vent devices terminate in the attic cavity, the following requirements must be met:
- - - - (A) The attic cavity must be accessible;
- - - - (B) The sealing device must be installed a minimum of 6 inches above the insulation materials; and
- - - - (C) The attic must be vented in accordance with § 3280.504(c)(1)(i);
- - (3) Mechanical vents must be installed in accordance with the vent manufacturer's instructions.

24 CFR 3280.604 - Materials: https://www.law.cornell.edu/cfr/text/24/3280.604
- Plumbing System Components for Manufactured Homes and Recreational Vehicles - ANSI/NSF 24-1988. (This is the closest thing I saw which might include mechanical vents and AAVs, I didn't find a specific listing for them.)

...........as I said, they are allowed, and used, in the building of HUD Code homes..........Greg

Originally Posted by Jerry Peck

The drain from the right, from a standpipe for a clothes washing machine, is 2" and goes into a combination wye and eight bend (which is allowed for that use because: a) the fitting itself is allowed for that use; b) the vent for a clothes washer standpipe is the standpipe itself, the hose going into the standpipe from the clothes washer should never ... never ... fill the standpipe and seal it off)..............


Looks funky, but right, to me......

What is bothering me is this - the trap at the bottom of the standpipe, not shown in the pic. The trap arm gets not much air from that end.
The long sweep means air from the vent stack, the 'AAV', has to flow up that curved elbow, the eight bend. 2" diam makes it work, but it is awkward.

I was quoting the NSF standard number from memory. The actual standard is NSF 24.

NSF 24-2016
Plumbing System Components for Recreational Vehicles

The HUD code is referencing an older version of the NSF standard.

Originally Posted by Mark Reinmiller

NSF 24-2016
Plumbing System Components for Recreational Vehicles

The HUD code is referencing an older version of the NSF standard.

And until the HUD code references the newer standard, the edition of the standard which is referenced is the edition of the standard which is applicable - 1988.

The wheels of government turn slowly ... v-e-r-y s-l-o-w-l-y in some cases. Especially where there is no $$$$ greased lobbyist promoting 'something new'.

Their thinking may be ... if it's worked for 30 years ... it ain't broke ... if it ain't broke ... there is nothing to fix ... so why fix it?

It's not an S trap. We all agree on this, hopefully.

AAV's were discussed.

Still leaves two waste lines and one vent.

907.1 Individual vent permitted. Each trap and trapped fixture is permitted to be provided with an individual vent. The Individual vent shall connect to the fixture drain of the trap or trapped fixture being vented.


http://www.plumbingpros.com/pdf/dwvents.pdf

(underlining and bold are mine)

Originally Posted by ROBERT YOUNG

Still leaves two waste lines and one vent.

907.1 Individual vent permitted. Each trap and trapped fixture is permitted to be provided with an individual vent. The Individual vent shall connect to the fixture drain of the trap or trapped fixture being vented.


http://www.plumbingpros.com/pdf/dwvents.pdf

Not "required" to be individually vented.

Originally Posted by Jerry Peck

No "S" trap is present (because it ties into a vertical vent with a sanitary tee).

No AAV is present (there is a mechanical vent installed).

The height for the AAV (when installed, and the height of the mechanical vent - which is not permitted there) only needs to be 4 inches above the weir of the trap.

Sorry, mechanical trap.

Am I mistaken or does the washer require a separate wet vent?

Originally Posted by Mark Ryan

The line coming in from the right is the washing machine drain line.

NO!

first give away is BOCA vent. It is double trapped. How would you snake that!
I see something like that and I tell my customer the first thing we have to do is replumb it before I can snake it . Will it work yes! bUT IT IS HOME OWNER DONE AND WRONG!
Pay me know or pay me later.

Morning David.
I see one trap and 2 waste lines.
The OP acknowledged there is a standpipe upstream.
Jerry correctly pointed out the 8" wye complies to a plumbing code.
If that is the case, each waste line and trap therein is accessible for mechanical snaking. The mechanical trap is being assessed.

Review the thread. There is a lot of great reference material offered on this subject.
Best Robert.

Trap arm needs to be 2 times the trap arm diameter....so there should be a small section of pipe between the trap bends and the drain vent (sanitary t)....IRC 3201.6-7, 3105.1-3,3201.1

Originally Posted by Ray Thornburg

Trap arm needs to be 2 times the trap arm diameter....so there should be a small section of pipe between the trap bends and the drain vent (sanitary t)....IRC 3201.6-7, 3105.1-3,3201.1

Doesn't actually require a "small section of pipe" between the trap and the vent, it requires "length" (what the code refers to as "developed length"), and the two fittings appear to provide that "length" between the trap weir and the vent.

Your reference to 3201.6-7 indicates you are referring to number of fixtures per trap, and there is only one per trap (a clothes washer standpipe has its own trap, not shown in that photo).

Originally Posted by Jerry Peck

Doesn't actually require a "small section of pipe" between the trap and the vent, it requires "length" (what the code refers to as "developed length"), and the two fittings appear to provide that "length" between the trap weir and the vent.

Your reference to 3201.6-7 indicates you are referring to number of fixtures per trap, and there is only one per trap (a clothes washer standpipe has its own trap, not shown in that photo).

Spoke too quickly I meant to say P 3105.3 a vent shall not be installed within two pipe diameters of the trap weir.....so it sounds to me like a small section of pipe....maybe 3" for 1.5" pipe. The above picture appears to have no trap arm at all.....am I wrong?

Originally Posted by Ray Thornburg

Trap arm needs to be 2 times the trap arm diameter....so there should be a small section of pipe between the trap bends and the drain vent (sanitary t)....IRC 3201.6-7, 3105.1-3,3201.1

Thanks Ray, misplaced reference.
Best

Originally Posted by Ray Thornburg

Spoke too quickly I meant to say P 3105.3 a vent shall not be installed within two pipe diameters of the trap weir.....so it sounds to me like a small section of pipe....maybe 3" for 1.5" pipe. The above picture appears to have no trap arm at all.....am I wrong?

Yes, you are wrong (you did ask ) in that the "two pipe diameters" is not a length of pipe, it is a length (developed length) as specified - between the weir of the trap and the vent fitting (where it gets air, i.e., is 'vented').

Measure from the weir of the trap to the end of the fitting, it is likely between 1-1/2" to 2", install another fitting to the vent and you have doubled that length, likely meeting the minimum required trap arm length to not be considered crown vented.

You are correct in that 'there is a short length of pipe' connecting one fitting directly to the other fitting (i.e., a street fitting may not work as a street fitting may allow too short of a length between the trap weir and the vent), but I read your intent as meaning there is a 'short length of pipe' is needed 'between' the two fittings.

I have a file back at the office with the code and image for vertical waste pipe venting requirements. I will try to remember to post it later on.

Fixture venting

International Residential Code 2003
Chapter 31 Vents
Section P3105 Fixture Vents
P3105.3 Vertical leg for waste fixture drains. A vertical leg (see Figure P3105.3) is permitted within a fixture drain of a waste fixture in accordance with the following criteria:

1. Minimum trap diameter shall be in accordance with Table P3201.7.
2. The diameter of Section A shall be equal to the diameter of the trap.
3. The length of Section A shall not be less than 8 inches (203 mm) and in accordance with Table P3105.1.
4. The diameter of Section B shall be one pipe size larger than the diameter of Section A.
5. The length of Section B shall not be more than 36 inches (914 mm).
6. The diameter of Section C shall be one pipe size larger than the diameter of Section B.
7. The total length of Section A and Section C shall not exceed the distance allowed in Table P3105.1.
8. Bends shall be the diameter of the largest connected section.

fixture vertical leg for drain fixtures.JPG

Originally Posted by Jerry Peck

Yes, you are wrong (you did ask ) in that the "two pipe diameters" is not a length of pipe, it is a length (developed length) as specified - between the weir of the trap and the vent fitting (where it gets air, i.e., is 'vented').

Measure from the weir of the trap to the end of the fitting, it is likely between 1-1/2" to 2", install another fitting to the vent and you have doubled that length, likely meeting the minimum required trap arm length to not be considered crown vented.

You are correct in that 'there is a short length of pipe' connecting one fitting directly to the other fitting (i.e., a street fitting may not work as a street fitting may allow too short of a length between the trap weir and the vent), but I read your intent as meaning there is a 'short length of pipe' is needed 'between' the two fittings.

Sounds like you're telling me I'm right...that the trap arm appears a little too short...is that correct?
trap-bw-2d.jpg
Around here I've noticed most plumbers will cut a section of pipe equal to the minimum trap arm length to use between the fittings to be on the safe side of meeting this requirement. From the picture above it appears that the minimum trap arm length starts at where the water in the trap turns to drain into the trap arm.

Originally Posted by Ray Thornburg

Sounds like you're telling me I'm right...that the trap arm appears a little too short...is that correct?

Wrong again.

I am saying that the trap arm looks like it might be long enough ... all based on presumptions from the photo, the angle of the photo (which can be optically deceiving) and the length of fittings.

trap-bw-2d.jpg
Around here I've noticed most plumbers will cut a section of pipe equal to the minimum trap arm length to use between the fittings to be on the safe side of meeting this requirement. From the picture above it appears that the minimum trap arm length starts at where the water in the trap turns to drain into the trap arm.

In the drawing you included, see where it says "Trap Weir"? That is the point you start measuring from (as you described), not the end of the fitting. On an 1-1/2" fitting you will gain about 1-1/2" to 2" from the trap weir to the end of the fitting, put two fittings back to back, and you probably have 3" to 4" of length, and only 3" is needed to meet the minimum to not be crown vented (crown vented is not allowed).

Originally Posted by Jerry Peck

Wrong again.

I am saying that the trap arm looks like it might be long enough ... all based on presumptions from the photo, the angle of the photo (which can be optically deceiving) and the length of fittings.



In the drawing you included, see where it says "Trap Weir"? That is the point you start measuring from (as you described), not the end of the fitting. On an 1-1/2" fitting you will gain about 1-1/2" to 2" from the trap weir to the end of the fitting, put two fittings back to back, and you probably have 3" to 4" of length, and only 3" is needed to meet the minimum to not be crown vented (crown vented is not allowed).

I respect your opinion so I will consider your thoughts on this matter carefully. I think you are right about the angle of the photo for sure.....To me it just doesn't look like three inches can fit between those two pipes....Thanks....

Originally Posted by Ray Thornburg

I respect your opinion so I will consider your thoughts on this matter carefully. I think you are right about the angle of the photo for sure.....To me it just doesn't look like three inches can fit between those two pipes....Thanks....

Ray,

In the smaller sizes, say 3 inch and less or so, the length of the pipe going into the fitting is typically close to, may just a little less than, the size of the pipe (rule of thumb from experience), the larger sizes I have forgotten how much they go into the fittings.

Thus, using that rule of thumb (which is, of course, fallible), that 1-1/2" pipe would go into the fitting about 1-1/4" to maybe 1-1/2", and then there is a little length of fitting beyond that before the weir - say about 1/8" to 3/8" (so let's say 1/4"), which would make the distance from the weir to the end of the fitting right at 1-1/2" (give or take), and two fittings would make that right 3" ... then add in for that little space between the fittings (maybe another 1/8") ... and that would meet the two pipe diameters requirement (or be very close to it).

Of course, though, the only way to know is to be there and measure it ... but an inspector walking by may use the same calculation I used above and think 'Yeah, that'll probably meet the requirement.' and then move on.

I prefer Ray's schematic , but think you both put forth some commendable points of reason.

Originally Posted by ROBERT YOUNG

I prefer Ray's schematic , but think you both put forth some commendable points of reason.

Robert,

No need to duck ... ... Ray's drawing simply shows a cross-section and points to the weir of the trap, which my annotations on the photo referenced.

Ray's drawing helped point out one end of the measuring points for trap arm length.

Jerry, as always thanks. I will review the schematics.
Both of you developed the great discussion allowing me to follow it point by point. Much thanks, Jerry and Ray.

There is someone I am missing. Wish I could put my finger on it.
1: The fixture venting has be eliminated as was the non S trap that started the thread.

The (2) lateral fixtures discharge pipes proximity/clearance on the vertical wet vent bothers me.
Can someone add to this?
Much thanks.

Originally Posted by ROBERT YOUNG

The (2) lateral fixtures discharge pipes proximity on the vertical wet vent bothers me.
Can someone add to this?
Much thanks.

Not exactly sure of your question, but fitting are made for two back to back fixtures - special double sanitary tees.

Thanks for the reply.
Double sanitary tees are "engineered" for two fixture drain pipes to connect to one vertical waste line.
My question is, when two fixtures are discharged into a vertical waste line/pipe without the use of a sanitary tee is there a clearance requirement for each fixture discharging on the vertical waste line.

Originally Posted by ROBERT YOUNG

My question is, when two fixtures are discharged into a vertical waste line/pipe without the use of a sanitary tee is there a clearance requirement for each fixture discharging on the vertical waste line.

I guess I am not following your question.

What type of clearance are you asking about?

Originally Posted by Jerry Peck

Ray,

In the smaller sizes, say 3 inch and less or so, the length of the pipe going into the fitting is typically close to, may just a little less than, the size of the pipe (rule of thumb from experience), the larger sizes I have forgotten how much they go into the fittings.

Thus, using that rule of thumb (which is, of course, fallible), that 1-1/2" pipe would go into the fitting about 1-1/4" to maybe 1-1/2", and then there is a little length of fitting beyond that before the weir - say about 1/8" to 3/8" (so let's say 1/4"), which would make the distance from the weir to the end of the fitting right at 1-1/2" (give or take), and two fittings would make that right 3" ... then add in for that little space between the fittings (maybe another 1/8") ... and that would meet the two pipe diameters requirement (or be very close to it).

Of course, though, the only way to know is to be there and measure it ... but an inspector walking by may use the same calculation I used above and think 'Yeah, that'll probably meet the requirement.' and then move on.

Thank you for your replay....like I said I respect everyones opinion here and have learned a lot reading the various debates. However I have taken the time to take some measurements. It appears that the trap arm cannot be inserted into the fitting more than 5/8". In addition it is sloped in such a way that the top of the weir begins at the lip where the trap arm can no longer be inserted (the point where the trap can no longer hold water and must drain off). This means that the minimum trap arm length is 3" for a 1.5" pipe and there would be 1.75" of it visible between the fittings. See attached photo. In the photo the trap arm I cut was exactly 3" long.

Trap Arm minimum.jpg

This make sense because if the fittings could just be jammed together why have a minimum trap arm distance at all. The fittings are designed so that you must insert a trap arm length of your choosing. Weir starts at the lip. see photo below.

trap weir starts.jpg

If you still feel I am wrong I sure would like a better explanation....thanks...Ray

Ray, I do not know if this will help as well, it is from CD
.proper vent location.jpg

Originally Posted by Jerry Peck

I guess I am not following your question.

What type of clearance are you asking about?

Both fixtures are discharging into a "vent", not a wet vent.
A double sanitary tee was not attached.
Is there a minimum/maximum fixture clearance when avoiding a double sanitary tee.
The P traps may not the same height.

Originally Posted by Jerry Peck

That's not a 'Y', that's a 'combination wye and eight bend', it is allowed to be used for changes in direction as follows: horizontal to vertical (as shown in the photo); vertical to horizontal; horizontal to horizontal. See Table P3005.1 in the IRC.

Jerry, the term would be 45% wye and combination wye and 1/8" bend.
Do not mean to correct you.

Originally Posted by ROBERT YOUNG

Jerry, the term would be 45% wye and combination wye and 1/8" bend.
Do not mean to correct you.

Robert,

Look the term up in the code, the term is what I used "combination wye and eight bend".

I am trying to correct you to the correct and proper terminology.

Originally Posted by Jerry Peck

Robert,

Look the term up in the code, the term is what I used "combination wye and eight bend".

I am trying to correct you to the correct and proper terminology.

Much appreciated as always.
Much regards Jerry.

This is what I got when googled the 2 fittings.
http://www.supplyhouse.com/PVC-DWV-C...lbows-14825000

https://www.supplyworks.com/Sku/455278

Originally Posted by Jerry Peck

Look the term up in the code, the term is what I used "combination wye and eight bend".

Originally Posted by ROBERT YOUNG

Much appreciated as always.
Much regards Jerry.

This is what I got when googled the 2 fittings.
http://www.supplyhouse.com/PVC-DWV-C...lbows-14825000

https://www.supplyworks.com/Sku/455278

Robert,

You quoted me, but apparently did not read what you quoted as you apparently did not do what I said in the quote - curious as to why you bothered to quote me if you were not even responding to what I said.

I was not paying attention.
Will pay more attention.

As to your post #61 “Look the term up in the code, the term is what I used "combination wye and eigth bend".”
I am not a code inspector. I want my clients to understand the manufactured name of the fittings.

As to your post #56, What type of clearance are you asking about?
Vertical clearances for 2 fixtures discharge into a vent.

Jerry lots to plumbing.
I do not mean to correct anyone but get more informed.

Can stateside spelling be different?
Combination Wye and "Eighth Bend."