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Washing machine drain solution

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azward
azward Member Posts: 20

This is the PVC drain inside the vanity.

Is it possible to add a T above the p trap and tie the drain hose there from the washing machine?

IMG_20260205_105758.jpg
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Comments

  • mattmia2
    mattmia2 Member Posts: 16,167
    edited February 5

    no. the drain is too small for a washing machine, at least without adding a laundry tub to buffer it

    you'd have to add the washing machine to the stack that ties in to, assuming that has the capacity for it

  • azward
    azward Member Posts: 20

    I can upsize the PVC tube to 2" but the connection to the stack is fixed size

    This is the ci stack behind the drywall. ~2" piping. How do you cut the pipe and insert a T?

    Aug_3_2025_7_49_12.jpg
  • Intplm.
    Intplm. Member Posts: 2,948

    You would need a two inch pipe, measured from the inside diameter. From your picture you have inch and a half pipe. This would be too small to accept a washing machine. Cutting in a drain into what looks like four inch cast iron is where the washing machine should discharge to.

    mattmia2
  • Intplm.
    Intplm. Member Posts: 2,948

    There are a few different methods used in cutting cast iron pipe

    A reciprocating saw with cast iron cutting blade, metal grinder or a chain snap cutter.

    ( I have tried to upload a few demonstration videos here but have had some trouble. )

    mattmia2
  • mattmia2
    mattmia2 Member Posts: 16,167

    i would replace that steel pipe with pvc while you have it open. the cast iron stack is probably fine but that galvanized waste will be rusting out soon.

    Intplm.
  • azward
    azward Member Posts: 20

    Could you push to YouTube and share the link?

  • mattmia2
    mattmia2 Member Posts: 16,167

    all of the smaller pipe in the wall that is gray and mottled in color is galvanized steel. it rots out after 3/4 of a century or so.

    ethicalpaulazward
  • azward
    azward Member Posts: 20

    Cut a section off, or cut the entire galvanized grid away, then plug in assembled PVC piping, join to the existing stubs using Fernco no hub couplings, correct?

    If not using PVC. Does such practice exist: cut off a small section and plug in a threaded T (black steel)?

  • mattmia2
    mattmia2 Member Posts: 16,167
    edited February 5

    i would remove the threaded pipe from the ci and screw a threaded pvc adapter in to to ci. it might unscrew but if it doesn't it is easy enough to cut the pipe close to the ci stack fitting then make 2 cuts almost to the threads inside the fitting, break out a little piece of the pipe between the cuts with a small chisel then unscrew the remaining piece of pipe. once you cut the piece it it will release the tension on the pipe and it will unscrew easily.

  • pecmsg
    pecmsg Member Posts: 6,961

    just replace it all with PVC /ABS as long as it’s open.

    mattmia2Intplm.
  • azward
    azward Member Posts: 20

    Thanks for all your posts.

    Back to the initial question.. now I see the code requires minimum 2" pipe for a washer, connecting to the existing PVC pipe as is will cause water back up.

    If I change the PVC pipe to 2", does that make it sufficient to accept the washer drain by providing enough buffer?

  • pecmsg
    pecmsg Member Posts: 6,961

    just replace it all while the wall is open!

    Intplm.
  • azward
    azward Member Posts: 20
    edited February 6

    Heard you.

    The wall is already closed. See my first post and this

    The washer is planned behind the wall. It will be a front loading 2.4 cu ft washer dryer combo that features water saving.

    IMG20250801202125.jpg
  • KC_Jones
    KC_Jones Member Posts: 5,921

    My understanding is you need 2" all the way to the main drain stack in the wall. If you are proposing adding a 2" stub outside the wall, that's not going to cut it.

    In addition to that, will you be able to have the proper height requirements for the drain hose? I grabbed this from a whirlpool manual, but as far as I know they all have these requirements. 4" inserted into the pipe, Minimum 24" tall and straight down into a trap. I really don't see how you would accomplish any of this under a bathroom sink.

    image.png
    2014 Weil Mclain EG-40
    EcoSteam ES-20 Advanced Boiler Control
    Boiler pictures updated 2/21/15
    azward
  • Intplm.
    Intplm. Member Posts: 2,948
    edited February 6

    Everything is finished!? To your first post then. The answer is no, you cannot install it where you ask.

    If you can access the wall from the other side of the finished bathroom, exposing the cast iron stack there, then you should be able to add a washing machine.

  • hot_rod
    hot_rod Member Posts: 27,136

    what is the 2” pipe connected to the heel outlet for the toilet?

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    Larry Weingartenmattmia2
  • Intplm.
    Intplm. Member Posts: 2,948
  • azward
    azward Member Posts: 20

    Shower drain

    I was told the toilet flush might cause the shower drain p trap to lose seal, or it might work out ok. I have yet tested it out.

  • Larry Weingarten
    Larry Weingarten Member Posts: 4,048

    Hi, Two thoughts. It would be working with physics more than code, but you could add a valve to the washer drain outlet to slow it down. It would work, but's a bit of a hack…😈 The other thing is at the shower, copper pipe is attached directly to steel pipe. This will fail as the copper forces the steel to rust. It's another reason to redo the water lines… possibly in PEX.

    Yours, Larry

    bjohnhyazward
  • hot_rod
    hot_rod Member Posts: 27,136

    that is an illegal connection as it is before the toilet vent, which is the cast iron stack

    Is there a vent on the 2” pvc before the shower trap?

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    mattmia2
  • azward
    azward Member Posts: 20

    Thanks. your post just reminded one more time of the gal corrosion.

    but the work has been completed that way. I'd wait for leakage to happen to give me a strong reason to redo everything.

    does the connection b/t the copper and steel pipe look like propress?

  • Larry Weingarten
    Larry Weingarten Member Posts: 4,048

    Hi, The connections look like copper female adaptors screwed onto steel pipe and soldered to the copper… I'm not seeing press. How fast they fail will depend on water qualities like conductivity and acidity. In agressive water, those connections could leak in months. With nice water they could go for years. I do not think of connections like those as "workmanlike manner", which contractors are supposed to deliver.

    Yours, Larry

  • hot_rod
    hot_rod Member Posts: 27,136

    the toilet flush will bounce the trap and may cause ut to loose its seal 5’ in two inch before it needs to vent

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    Intplm.
  • azward
    azward Member Posts: 20
    edited February 6

    Ok. I used to think there does not exist a copper pipe with threaded connection.

    He might have used Teflon or dielectric sealant b/t the steel and adapter, that may help as a buffer to slow down the rusting

  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 19,957

    I know 2" is required for a washer but I have seen many 1 1/2" standpipes and I was told by appliance technicians that a washer will pump to a 6' standpipe

    epmiller
  • azward
    azward Member Posts: 20

    5' in two inches? Do you mean the pitch of that PVC pipe?

  • mattmia2
    mattmia2 Member Posts: 16,167

    your joists are also essentially nonexistent, those should have been fixed before it was closed up unless there is another support system under the 1x wood.

  • epmiller
    epmiller Member Posts: 41

    @EBEBRATT-Ed I worked as maintenance for a company that had a bunch of group homes and except for a couple that were newer, there was nary a 2" wash machine standpipe in any of them. We went thru many different brands of machines and I never had to deal with a standpipe drainage issues. I really don't understand the code requirement of 2" drain line as the pumps on most household machines are 3/4" to 1" and really not that high volume, even our commercial grade equipment never gave us problems on 1-1/2" standpipes. We also had some machines that would pump almost 8' up without any special pumps. Funny how things can work fine when parts of the systems are not up to code.

    azward
  • azward
    azward Member Posts: 20

    Do you mean he opened a notch on the joist to channel the PVC pipe?

    It's probably ok. You see the steam pipe also goes through notches on all the joists. These joists are secondary structural. The major beams are along their perpendicular direction. I would not do such compromise. Next time it opens, I would repair it with fiberglass and reinforcement.

  • mattmia2
    mattmia2 Member Posts: 16,167

    the notches in the joists especially for the steam pipe means the span of the floor between the beams is essentially being held up by a couple pieces of strapping. the fix is to figure out how to route the plumbing and box out the joists to get the plumbing through or make it so the plumbing can run through a hole drilled in the middle of the joist preserving the top and bottom.

  • pecmsg
    pecmsg Member Posts: 6,961

    Being full dimensions and I assume old growth lumber it "Probably" wont fail.

    The plumbing should have been rerouted!

    mattmia2
  • Intplm.
    Intplm. Member Posts: 2,948
    edited February 7

    So, all agree that the pictured drain is a code violation.? That PVC drain would have to enter the stack behind the toilet and not as shown , but it seems to have worked out for the OP. But then this is off point.

    In order for a washing machine to have proper drainage it should be drained using a 2" drain with a 2" p-trap .

    To do this properly, the cast iron would need to be exposed and have the washing machine drain plumbed there. This would accommodate the newer high pressure pumps that are in pretty much all of todays washing machines.

    If the easy route were to be taken, drain water discharged from the washing machine would overflow into the room. Years ago the code changed from 11/2" to 2" . This code change was made because of the new high discharge / pressure pumps supplied in washing machines.

    The way to get this job done would be to access the wall from the other side of the new finished bathroom and cut into the cast iron vertical stack there.

    Alan (California Radiant) Forbes
  • azward
    azward Member Posts: 20

    the steam pipe is as old as this prewar townhome. so ppl at that time didn't mind notching the joists for plumbing. you mean replacing those joists and reroute the steel pipe? the project is too large to justify for a prewar row house. This requires reducing the bathroom to its raw state, jack support the walls on both sides.

  • azward
    azward Member Posts: 20
    edited February 7

    how does the 2" pvc connect to the 2 1/2" hole on the stack?

    i found this mechanical boss, but it supports up to 1 1/2" pipe

    pictures would help greatly

  • Intplm.
    Intplm. Member Posts: 2,948

    That "mechanical boss" is what's called a saddle tap or saddle fitting and are not plumbing code accepted in most areas.

    Here are some pictures as requested.

    shopping.jpeg

    One of these.

    shopping-1.jpeg

    Two of these. With the properly sized PVC, DWV Schedule #40 drain pipe.

    I suggest you hire a professional for this if you plan on following through.

    Where are you from?

    mattmia2
  • azward
    azward Member Posts: 20

    Location is near Jersey City.

    The stack weight above the cut would be over 300lbs, is this within the weight capacity of that PVC T?

    IMG_20260207_143232.jpg
  • mattmia2
    mattmia2 Member Posts: 16,167

    it was wrong then too. a lot of times retrofits got done by people that didn't know what they were doing carpentry wise. that is why renovating a bathroom in structures like this is a can of worms and the rough work is frequently far more of the job than the finish work.

    Alan (California Radiant) Forbes
  • azward
    azward Member Posts: 20

    Now I see the point.

    It looks like some temporary support needs to be in place before the PVC pipe is substituted in.

    I was looking for a draining solution that avoids demolition though.

    IMG20260207170732.jpg IMG20260207170637.jpg