Hello all...First time, log time!
Replacing old dishwasher and copper water line but need extended time before installing new DW and stainless flex line, without shutting off water to entire house. FWIW, I checked shutoff valve for leak by closing it and running a "quick rinse" cycle (10 min) test...No leak. Assuming, the new flex line gets attached at point A, how safe is it to disconnect the old copper line, at point A, for an extended time, before attaching the new flex line? OR do I need to cap it off? If cap off is needed, what would you use and where?

Shut off valve for DW under kitchen sink


Copper water line from shut off valve, through wall to DW.


Copper water line attached to old DW




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How long is an extended time ? For a few hours I wouldn't cap it, if for overnight or longer I'd use a 1/4" compression cap, at point A.

it is fine to disconnect 'A' and cap it with a 3/8" compression cap.
i would take 'B' apart, clean it up with some steel wool, put some grease on it and retighten.
the fitting you have there is a 1/2 x 3/8 compression union. a 3/8 flexible supply will fit right onto the side marked 'A'.

It is hard to tell without anything to compare it with, but if that is 1/2" (5/8 o.d.) copper on the right, then the reduced size MAY BE 3/8" i.d. (1.2" o.d.).

that is a 1/2" copper stop valve so the tubing is 5/8 OD -- 1/2 ID. then the plumber stuck a piece of 1/2 inch OD copper into the 1/2 ID copper and soldered it. then used a 1/2 x 3/8 compression union to run 3/8 to the machime.
that is a 3/8 male by 3/8 compression elbow at the DW inlet.
i'd bet the mortgage on it...

As for an extended time...I mean, at least, a matter of days.

A DIYer friend recommended to disassemble the copper, A, and remove the fitting between "A" & "B", and the new flex line will screw into the 1/2" nut "B"...
Thoughts?

Here's a closer pic of the body of the valve that I hope might be helpful:

the flexible connector has a female swivel end it will fit perfectly onto the male end of the fitting which you have labeled "A".
if the shut off stops the water then leaving it open for a couple of days will do no harm.. it will not all of a sudden open itself and flood the neighborhood.
lastly, 99% of dishwasher are now coming thru with a male hose thread for the water connection. (like a washing machine has). you will need a 3/4 female swivel hose thread x 3/8 compression 90. a very common item.
[www.google.com]

"A" is 3/8 compression

simply use a 3/8 OD compression cap

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638



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The new DW comes with the following flexible connector set, which I'd like to replace the copper line with:

that is perfect.. just be very careful when threading on that hose adapter. metal female threads going onto male plastic threads can be very easy to cross thread.

Great, thanks...Will do!

With the new flex line, do I need both 'A" & "B" with what looks like a fitting in between them? I'm considering disassembling and removing "A", and the fitting between "A" & "B", then screwing the flex line, directly into "B".
Thoughts??