1-1/4 in. drain plubming question...


I'm installing a 4-ft. kitchenette with sink and, due to space constraints, I am considering running 1-1/4" abs as opposed to 1-1/2" (the lines will tie into 1-1/2" about 8' downstream). What problems might I run into wrt to draining? TIA!
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What does the code call for? MLD
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On Sep 20, 9:31am, snipped-for-privacy@gmail.com wrote:

Current min drain pipe (in the wall, not under sink) is 2".
My older home (1930) had some 1 1/2 lines that over the years were problematic. I had all the cast iron laterals replaced with 2" ABS.
This sounds like a bootleg / non-code project.
Most code changes (modernization) are for safety or improved performance but there are millions of old installations that work just fine that aren't up to current code.
A drains at 1 1/4" (for any appreciable run length) are pretty small. I think you'd have trouble depending on sink usage (garbage disposal?)
Even 1 1/2" is rather small on a long length run....I would suggest re- thinking your design & work in 2", the result will more trouble free.
cheers Bob
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Bootleg, yes.

Rethinking my design includes the use of a concrete saw...blah ;-).
Thanks for the reply.
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You'll want to Tee in an air admittance valve after your trap under the sink. That'll keep the 8' run of 1-1/4 from sucking your trap dry.
s

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On Sep 20, 1:52pm, "Steve Barker DLT"

That's what I was worried about. It'll definitely be (dry) vented but as Wayne has suggested, I'll likely go with 1.5" Cu scraps that were destined for recycling.
Thanks again everybody.
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As others mentioned, a kitchen sink requires a 2" drain. Consider routing the drain through cabinets or having it stick out of the wall a little.
Also, the outer diameter of copper drains is noticeably less than that of plastic drains (ABS). For example 1.5" Cu and 1.25" ABS have about the same outer diameter. Since you are only going 8' the cost shouldn't be prohibitive.
Cheers, Wayne
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