Copper DWV Lines...

Hello,

I have a few questions about Copper DWV. I'm renovating a house that previously had all copper DWV. As needed I'm splicing in ABS with the Copper using Mission couplings.

In the current bathroom I'm working on I have 2 situations where I need to join to 1" copper. One is a drain from a sink to a 3" stack--all I'm doing here is capping the drain as it will not be used. I can't find mission couplings for 1" copper. I guess I need to use some other rubber type coupling but am looking for suggestions.

The other situation is where the drain becomes a vent, the copper changes from 1 1/2" to 1". I'm going to replace the whole line down to the stack with 2" ABS but I wanted to leave the roof penetration until I get a new roof. Is it OK to leave a small section of 1" copper at the top of the vent...If so, any ideas on how to connect 1" copper to 2" ABS.

Thanks for any help you can provide,
Mike

Follow up question...

Can I sweat 1" copper. At what size do you have to start brazing copper?

Thanks, this might be the answer to my question above.

Yes you can sweat 1" copper.

You can sweat any sized copper you will deal with in a house as long as it is above the ground...
You should braze any joint below ground...
We routinely solder up to 6" copper unless spec'd to be brazed...
The only copper smaller than 2 1/2" that we braze (if above ground) is medical gas piping...

Don't know if we're talking the same language or not but around here it's silver solder underground.
As for how to connect the copper to ABS ... have you thought about using threaded adapters and just screwing them together?

Here silver solder=brazing...

Copper to plastic threaded joints...... always screw the plastic into the copper...

OK, now I know I can sweat the bigger copper and the best way to join copper and ABS is a threaded connection. I also know that the copper pipe is 1 1/4" (not 1".)

Is there a problem with a small section of 1 1/4" copper vent at the top of a 2inch drain?

vent, at roof. Precise term.

mike

makes perfect sense being 1 1/4" copper since it is DWV, not pressurized. Wouls surprise anyone if some of it was 1 1/2" also.

Your last question is about leaving that size diameter opening at the roof, at the top of your new 2" vent, a PVC one. That is your question, but you called it a drain. It's a vent. Hope i understood that right, and hope this helps.

Leaving the opening only 1.25" diameter has no massive problem associated with it, and the drawback is probably so obvious to you that i shouldn't try to explain it. You have already said you'll put the 2" through the roof, when you get a roundtoit.

david

I'll let someone else answer the vent question... I can tell you that 1 1/4" is unusual and probably not to code anywhere. For me, I'd keep it 2" if anywhere near reasonably possible. The biggest thing you need to know is that it takes alot more heat to solder the bigger pipes...anything bigger than 3/4" is tough to do with the little cheap propane torches. If you've got oxy-acetylene torches then you're in great shape for anything. A b-tank with a turbo torch is the plumber's best friend! MAPP gas with a turbo torch is very very handy and will do the job.

Thanks, everyone, for the replies. I have the answers I needed. I'll go ahead and leave the 1.25 roof penetration for a while...I'll be needing a new roof soon...then I'll finish the 2" run. Sounds like I should be able to sweat 1.25 copper with a mapp gas torch pretty reasonably.

BTW, genie...you're right, some is 1.5" copper...only the vents are 1.25, when it gets to drain it changes to 1.5.

I'll probably have further questions when I get to designing the run because I'm adding a sink.

Thanks again,
Mike