Plumbing drain help

[MikeC55]

I'm replumbing an area where a sink used to be for a washing machine. I plan to use one of those outlet boxes for the drain (ABS plastic) with a 2" drain connection. I know I'll need a P-trap in the wall and the pipe I'm connecting to is 1-1/2 copper. Since I don't want to take out a 2nd mortgage, I'd like to adapt the copper to 2" PVC before the P-trap. Is this what I need to do that? I'm not quite sure I understand how this would connect to the end of a 1-1/2 pipe. You can't sweat it on there with the plastic inside...

https://www.supplyhouse.com/Sioux-C...-x-1-1-2-Male-CTS-MetalHead-Press-Fit-Adapter

Or this (looks like a shark bite-type) https://www.amazon.com/Adapter-1-5i...-Products/dp/B018A2ZJ00/?tag=atomicindus08-20

 

[hans109h]

Copper for DWV, aah the good old days. Pull it out and scrap it to pay for replacing with pvc? I'm sure someone will have the actual answer you're looking for

Hans

 

[The Cobbler]

to upsize to 2" is not a great idea... it will leave a pool of water at the bottom of the pipe and that will lead to residue getting there & eventual clogs.
There are fittings to adapt to copper with a tapered washer & a nut to tighten down like this... you can use what you're showing , just wrap a wet rag around it to keep it cool as you solder

 

[MikeC55]

Or what about this? https://www.supplyhouse.com/Spears-835-015-1-1-2-PVC-Schedule-80-Female-Adapter-S-x-FPT

https://www.supplyhouse.com/Elkhart-30368-1-1-2-Copper-x-Male-Adapter

I would have to solder a male pipe thread adapter on end of copper. I've not soldered copper that large before, is it something I can still do with a propane torch?

 

[Wiz02]

Or what about this? https://www.supplyhouse.com/Spears-835-015-1-1-2-PVC-Schedule-80-Female-Adapter-S-x-FPT

https://www.supplyhouse.com/Elkhart-30368-1-1-2-Copper-x-Male-Adapter

I would have to solder a male pipe thread adapter on end of copper. I've not soldered copper that large before, is it something I can still do with a propane torch?

If the pipe is dry and you clean the copper thoroughly and use flux, you should be fine. Get a heat shield if the pipe is not out in the open.

 

[MikeC55]

Cool, thanks, Wiz02.

 

[housewolf]

I would probably use something like this to transition from copper to pvc. Like was posted before, it’s not a great idea to increase pipe sizes like that. If you can do it in the vertical at least you wouldn’t have the pipe holding water. I’m not sure an 1-1/2” p-trap will handle the amount of water your clothes washer pumps out. If it’s possible, do it all in 2”

 

[dogdog]

Get a heat shield if the pipe is not out in the open.

This is very important if you are using a torch to sweat the copper pipes... or at least check the pipe area inside the wall and make sure nothing flammable like fiberglass insulation or news papers. Don't do it if you are not sure.

propane torch probably a TS8000 would work fine or TS4000 maybe....

 

[carlaisle]

The Sharkbite style Amazon job you linked will do the trick just fine. This here is another easy option. You could also just solder a threaded end on to the copper. You might need two torches (and an extra set of hands) to do that with propane, but it's easily doable. 2" is current code for a washing machine drain, but I wouldn't worry about that. You should make the transition in the vertical section of pipe. You don't want a drain reduction in a horizontal run. Junk will accumulate there over time and at some point that will come back to bite you.

 

[75gmck25]

In most cases you should not use 1 1/2" for a washing machine drain unless you have something to act as a buffer if the water flow overcomes the pipe diameter. That is one reason older houses drained the washing machine in to a deep utility sink, and then the sink drained into a 1 1/2" pipe. I'm not saying it won't work, but you really need to ensure that drain pipe can't fill up and start overflowing.

 

[MikeC55]

Thanks for the tips, guys. I understand about the possible excess flow for 1-1/2 pipe. I really don't have much choice, though, unless I rip out a finished bathroom, and even then, I know the main drain pipe to out of house is cast iron and my septic guy said I didn't want him to mess with that or it would cost a lot more (getting a new septic system). One thing I do know is that the existing washer drain is 2" PVC as far as the vertical pipe (open end for washer output) and P-trap, but it get's adapted to the 1-1/2" copper. The washer is maybe a dozen years old and had had no problems draining. I guess it could be a problem if the new machines pump the water out that much faster.

The reduction will be in vertical position for the new location. I'm planning to insert a T in the drain line where pictured, then a short stub, then adapter. In the photo, you can also see the old sink supply and drain. One of the 2 vertical 1-1/2 inch coppers is a vent (I think), but I'm not sure which one (ceiling is sheetrocked and even with borescope I can't follw the pipes all the way to other end). I suspect the one on left is a drain from upstairs bathrrom sink, and one the right is a vent.In any case, the T will be very close to both, so I think venting will be ok.

I am very careful when soldering in-situ pipes and always use a heat shield near studs. I'm not sure how I'll get in there to cut the pipe. Hacksaw, I guess. Not much room between pipe and block wall behind it.

 

[housewolf]

Ditch the soldering idea, use one of the mission couplings like I posted above. They are an approved, high quality fitting made to transition pipes with different OD. If I were doing this in a hospital or hi-rise, it’s what I’d use. I’d also recommend cutting the tee in the vertical pipe to the left of where you want the trap. I’m assuming it’s a vent, or eventually becomes one. In either event you’re not getting past the fact you’ll install or tie into a tee on its back but at least you’ll have something resembling a vent on it.
You can cut it with a sawzall or hacksaw blade, it’s likely pretty this copper. I have some of these for cutting up to 3” copper in a tight spot. If you have some they’ll probably work on 1-1/2”. I wouldn’t run out and buy them though

 

[carlaisle]

The vent should be on the left, but you're close enough it doesn't really matter. Sawzall would be my weapon of choice to make the necessary cuts. Hack saw will work just fine, too. If this was my house I would definitely put in a clean out while the wall is open.

 

[MikeC55]

If I understand correctly, I want to splice in a 2" PVC T into the pipe on the left of where the P-trap will go (the shiny, vertical copper). Am I correct that I would have to glue in 2" pipe stubs on the T ends and then the Mission coupler (1-1/2" to 2") would clamp on the stubs (it's designed to fit on 2" PVC, not the larger OD of the T itself).

 

[TurnipTruck]

I recently remodeled a 70’s house with copper dwv pipes. I was able to find Fernco rubber&stainless clamp couplers specific for joining large copper and pvc pipes. I even found one for pvc-iron.

The white pipes are painted copper, back when they were exposed.

 

[housewolf]

If I understand correctly, I want to splice in a 2" PVC T into the pipe on the left of where the P-trap will go (the shiny, vertical copper). Am I correct that I would have to glue in 2" pipe stubs on the T ends and then the Mission coupler (1-1/2" to 2") would clamp on the stubs (it's designed to fit on 2" PVC, not the larger OD of the T itself).

Correct you’ll have to glue short pieces of pipe into the tee. The couplings are “pipe size”. Make sure you get the correct size. Steel & PVC are same OD, cast iron slightly small, and copper smallest

I recently remodeled a 70’s house with copper dwv pipes. I was able to find Fernco rubber&stainless clamp couplers specific for joining large copper and pvc pipes. I even found one for pvc-iron.

The white pipes are painted copper, back when they were exposed.

Fernco/Mission - Ford/Chevy
“Back in the day” I think Fernco only made adapter couplings w/o the SS band and Mission made none w/o the. Or maybe it was just the environment I came up in. The terms kind of took on their own meaning. I believe both companies have a similar line today.
Looks good.

 

[MikeC55]

Thanks, Housewolf!

 

[csp]

If you choose to use a solder on threaded fitting on the copper make it the female side. You never want a copper/black pipe/other metal male fitting threaded into a plastic female fitting. It has the potential to crack the plastic since it's a tapered fitting and will likely do it long after you have everything buried behind drywall.

Always go male plastic into female metal.

My home has all copper DWV fittings and the washing machine drain is also 1-1/2". Haven't had an overflow yet.

 

[The Cobbler]

potential to crack the plastic since it's a tapered fitting and will likely do it long after you have everything buried behind drywall.

Always go male plastic into female metal.

a good point, but, in my opinion, the pipe should never be so tight to crack the fitting.
you will have a good seal long before you crank it in so far to ever crack the plastic

 

[cgrutt]

I recently had to redo an old shower drain used a Fernco to attach new PVC to old copper drain pipe. Not pretty but it worked.

 

[MikeC55]

Always go male plastic into female metal.

Makes sense.

 

[csp]

a good point, but, in my opinion, the pipe should never be so tight to crack the fitting.
you will have a good seal long before you crank it in so far to ever crack the plastic

The problem is plastic gets brittle and dry over time and will change its form while the metal will not. It's not going to crack when it's initially tightened, it's down the road that this happens. How long? Who knows, that's why you don't use a female plastic fitting to play it safe.

 

[PackagingSea]

Looking at your setup, I'd go with the Mission coupling approach housewolf mentioned. I've done a similar transition and those couplings work great, way easier than trying to solder in that tight spot against the block wall.
Since you mentioned the existing washer has been draining fine for 12 years on that 1-1/2" copper, you should be good flow-wise. The vertical transition will help avoid any pooling issues.
One heads up from experience, if you run into any code questions or complications with the venting, there's a good firm at https://www.plumbprosc.com/residential-plumbing-services-in-hilton-head/ that knows their way around these older copper DWV systems.