When the washer discharges faster than the standpipe will accept it, it can spew out around the washer hose like a gyser. That's why I prefer to discharge into a wash tub. With your proposed hookup, the water could also back up into the sink.

So this set up will be OK? Are you saying my sink can serve as the back up mechanism?

I would think sealing can create a vacuum, no? Doesn't it need to be opened so the water can "fall"?

What is the AHJ?

I just measured my washer drain in the wall...it has a 2" drain, so I do not think the set up will work. And I never see water coming into the sink, so my drain can handle the flow.

AHJ stands for Authority Having Jurisdiction. In other words, whoever is responsible for building code interpretation in your area (the county/city building inspector)
A 2" drain will handle almost twice the flow of a 1-1/2", I would not expect a problem with the larger as I have experienced with the smaller.
I don't believe there would be a vaccuum formed, but neither do I see a problem if there is one

I am confused, but to be sure I am doing the correct thing, I can T tap my existing 1-1/2" line that goes from the sink to the main drain about 10 feet away. And having the sink will allow it to fill up the sink incase the flow from the washer is too much as an added security feature. Also, to avoid the water spilling behing the wall, can I leave the vertical washer drain on the exterior of the wall?

Here is the picture of the area. As you can see, I removed the washer, dryer, and slop sink. The current slop sink was located about 9 feet away from the main vertical drain in the house. I would need to tap into this for the vertical washer drain avoid discharging into the sink. I did notice there was no vertical vent on this 1-1/2" line, I always read discussion on venting, but did not see any. Also, I temporarily stuck the AC drain into the p-trap in case you are wondering what is sticking out of that.

Why not remove the 1 1/2" pipe and replace it with a 2"? You can leave the 1 1/2" connection on the sink but the washer discharge should have a 2".
Below is an example of a setup.

Here is a link that might be useful: plumbing

i think that the code minimum is 2" for the washer. Lazypup is the authority here on it. shoot him an email with some pics of what you have and maybe a drawing of what you want to do. he can tell you what must be done.

Per code both the washing machine & the air conditioner condensate drain line are required to discharge into an approved "Indirect waste receptor".

An approved indirect waste receptor is either a laundry sink or a laundry standpipe.

The post states that the existing 1-1/2" line runs 9 from the sink location to the stack, which is nearly twice the length currently allowed for a 1-1/2" un-vented fixture arm however, we can assume that the line is original work and further assume that it met code approval at the time of installation. The problem is that if you add to or alter the original layout in any manner you would be required to upgrade all the work to the code that is in force at the time of the new work.

This then leaves you an option. You can re-install the sink in the original manner and continue to use the sink as the approved waste receptor for the washing machine & AC condensate drain line or you can remove 1-1/2" horizontal line all the way back to the stack. You cannot install a laundry standpipe on the 1-1/2" line because code requires a standpipe to be a minimum of 2". Furthermore, a standpipe is rated at 2DFUÂs (drainage fixture units) and a sink is rated at 2DFUÂs for a combined load of 4DFUÂs while a 1-1/2" line is rated for a maximum of 3DFUÂs.

Code requires that a washing machine standpipe "Must Be" a 2" line. Once the 2" line is installed you could install both the sink and standpipe because the combined load would be 4DFUÂs while a 2" line is rated for a maximum load of 6DFUÂs.

I am assuming from the screen name that the structure in question is in New York and the NY plumbing code is based upon the IRC (International Residential Code).

Under the IRC we compute the maximum allowable length of a fixture arm by dividing the diameter of the pipe by the pitch. All pipes 3" or under are required to have a ¼" per foot pitch therefore the maximum length of a 2" fixture arm would be 2"/.25"= 8Â. Be very careful here. The pipe must be run with a ¼" per foot pitch but if you happen to get a steeper pitch the maximum length is shortened. Code requires that the bottom of the pipe at the trap weir may not be higher than the top of the pipe at the vent opening on the downstream end.

The next problem, if that vertical stack is serving a watercloset (toilet) on the upper floor you may not connect an un-vented fixture arm to the stack.

If there is a watercloset on the floor above, or if you require the standpipe location to be at a point greater than the allowable 8 you will be required to install a vent on the horizontal line within 8 of the fixture traps. Fortunately you are under the IRC so there is a simple solution to this problem. The IRC requires all structures to have one "Main Vent" which must run undiminished in size from the house main drain through the roof. After that is achieved you may reduce the size of auxiliary vents to ½ the diameter of the line they serve, but not less than1-1/4" Auxiliary vents may be terminated through the roof, in the attic space, through the wall under some very strict limitations or you may use an unlimited number of AAVÂs (air admittance valves). In this case you could install a Wye & 1/8 bend at any convenient point on the horizontal line within 8 of the furthest trap, then install a riser on the wye&1/8bend and run it up to a point that is a minimum of 4" above the level of the highest trap and install an AAV. The AAV must be installed in an accessible location so you could either;
1. Offset the vertical riser outside the wall and install the AAV
2. You could install the AAV in the wall with a vented removable cover grille that would allow air into the AAV.

If the sanitary tee on the vertical stack where the 1-1/2" line currently connects is a 3x3x3" tee with a reducer on the side inlet you could remove the reducer and install a 2" reducer.

If the Tee is a 3x3x1-1/2" reducing tee you would be required to remove that tee and replace it with either a 3"sanitary tee with a 2" reducer on the side inlet or a 3"x3"x2" reducing tee. Keep in mind that changing a tee on a cast iron stack is an extremely dangerous job and one that should never be undertaken by an unskilled novice that has not been trained in the hazards.

It was mentioned in one of the previous posts that you should tape or otherwise seal the top of the washer standpipe. WRONG- that is totally code prohibited. Code requires that the top of the standpipe must remain open to atmospheric air. And before anyone chimes it telling us about the cute little rubber caps they sell in the hardware stores to cap your standpipe, those caps are code prohibited, but then we could make a sizeable list of code prohibited items sold every day.

Wow, Lazypup, some response...thank you !

If you want to use something that holds the drain hose in the standpipe and is still vented to the air, fernco makes a cap with vent holes. I have one and it works great.

Lazypup, here are the pictures of the connection. Unfortunately when I removed the wall, I found it was a 1.5 inch connection, and I also found the clean out behind the wall (something I will provide access for before I close the wall).

Question, does this procedure seem valid below?

I am considering cutting with a good carbide blade on a sawzall directly below the 1.5 inch connection, then adding in a PVC and fernco connection to the existing cast iron main going into the floor. I appears if I cut directly below the 1.5 inch connection, I will have 2 inches of cast iron pipe to get a fernco around. This cast iron piece is the kind that has the okam and lead fill (spelling??). I know cast iron has issues, but it is cuttable in this fashion? I would remove the stud for temporary access to cut this.

I will then take a 4" PVC section with the 2" nipple and make the connection with a fernco. It appears the 2" connection may be a bit higher because I need to add a small piece of 4" PVC straight pipe to get the fernco connection around. Then I would remove the cast iron clean out section and continue PVC along with a reducer to 3 inches, install a 45 degree turn, install a 3" clean out and then connect to the 3" copper with a fernco. The clean out will get it from out behind its current location behind the stud.

Lazypup...someone....is my concept valid? Thanks...

I have a much simpler solution the will not require cutting the cast iron.

First remove the stud that is in front of the cleanout and remove the cleanout cap. (You may need to use a hammer & chisel and break the cap out)

Clean the female threads in the 4" cast iron cleanout opening then install a 4" PVC Male thread adapter into the CI cleanout hole. (Be sure to apply pipe dope to the threads on the male thread adapter.)

Cut a X-close nipple of 4"PVC pipe and insert it into the thread adapter, then attach a 4"x 4"x2" WYE on the nipple so that the Hubs of the Thread adapter and the WYE & 1/8bend are almost touching each other.

On the opposite end of the 4"WYE install a 4" Female thread Adapter and a cleanout cap. In this manner you have retained the original cleanout location.

You can now tie in your new 2" PVC line to the side opening of the WYE & 1/8bend.

In this manner you cleanout will be extended outside the stud wall where it is required to be and you will not have to cut any CI pipe.

You will also be required to install an AAV on the 2" horizontal line as was described above.

You can then cut & cap the existing 1-1/2" copper line.

Question...if you have a laundry sink, can't that provide a source of back up in case the 1.5 inch washer discharge line gets backed up? This way, all that work gets avoided. The washer pipe will be higher than the sink. It may not be to code, but it may work fine, no?

I like your idea though Lazypup.

Lazypup...thanks. I think that method may not work because their is a toilet in the area and the connection to the existing 4" cast will stick out too far in the room. With those connections...how much length is that approximately? If I want to connect a sink, I guess I should still use the 1.5 inch connection in addition because the other method may be too high by the time it gets to the sink.

I doubt that cutting the cast fitting with a sawzall will work. If height is an issue, just replace the two cast fittings with PVC. Cut the copper above the cast iron, drill out the lead in the joints and pull (or break) out the cast fittings. Replace with PVC and the appropriate rubber connecting fittings. Vent as per lazypup's notes.

Brewbeer...If I drill out the lead and pull out the cast iron, how does a new PVC fitting connect back into the cast iron piece comming out of the floor? I assume it is not a female threaded piece which is why lead and oakum is used? Does a propane torch heat the lead enough to soften it so the fitting comes out easier.

ABSOLUTELY DO NOT ATTEMPT TO HEAT THE LEAD WITH A TORCH. Sewer gas is highly flammable and in high concentrations it can be explosive. In fact, it is very risky to even smoke while working on DWV piping.

Use a drill to drill a series of holes close together to get a starting point in the lead, then use a pointed pry tool to pry the lead out. I use an old automobile tire tool but someone else commented that a Craftsman gasket puller also works. Once you get it started it will come out easy.

Once the lead is out you will need to pry the old oakum out and use a wire brush to clean the inside of the hub.

You can get a fernco rubber donut to fit the new PVC into the hub.