New kitchen counters are coming in soon and I need to prepare the sink plumbing. I think I can do a half-decent sweating job and I have the right tools. Plan is to un-sweat the existing tees and to put on Sharkbite caps until the new counter is in. Then sweat on new tees with new quarter turn valves, extension pipes for the hot and cold and the valves for those.

Is this a solid plan?

Also, I cannot quite make out what comes after the tee on hot. Is this a 1/2” threaded adapter that is sweated on the tee?

And finally, in which order would you do this? Should I make the top assemblies first and sweat them on supply popes as a last step?

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  • Other than the sink faucet what else will be hooked up to this, dishwasher? ice maker? What do you plan to do with the waste arm, it looks like it's glued in place. Instead of shark bite caps why not just cut the copper pipes and put compression fitting1/4 turn valves on instead. If you do it that way you don't have to sweat everything under the sink. You can sweat everything on your work bench and then just pop it into the compression fitting. One of the plumbing pros will probably come along with a better answer. – Platinum Goose Dec 1 '20 at 18:38
  • @Platinum-Goose, yes, the DW valve shown on hot, icemaker on cold. I’ll actually have double valve for 2 dishwashers. I will be cutting the drain pipe and put a flexible fenco extension. – David Dec 1 '20 at 18:46
  • It's very difficult to answer this question without having the sink(s) in place or at least knowing the specific dimensions of the layout under there. Sink profile (single, double, regular depth or deep, size of disposal, etc.)? I wouldn't do much here until you have a better idea of what you're working with. Otherwise you could find yourself redoing a lot of the work. – HoneyDo Dec 1 '20 at 18:57
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    Another thing to be careful about is if you go with a deep sink and a disposal you may need to adjust the height of the drain in the wall. – Platinum Goose Dec 1 '20 at 19:48
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    Platinum Goose makes a good point. NOW is the time to address that as you can open the wall before the cabinet is in. Perhaps best anyway, new sanitary tee and deal with that wire. – Alaska Man Dec 1 '20 at 19:51

Your valves appear to be a compression connection not threaded on to a threaded adapter. No need to un-sweat, you have plenty of pipe to work with, just cut below the tee.

Once your cabinet is put in over your stubs You will be able to build it any way you like. A water hammer leg at the top of each line is a good idea. You can choose any type valves you want, compression, threaded or soldered.

I prefer to have one valve for each supply line, as opposed to two lines off of one valve, so if the dishwasher goes on the blink you do not have to turn off water to the sink while waiting for it to be repaired. (same for fridge etc.)

  • it appears that I have enough pipe bit once I slide in old cabinet, I only end up with about 1”-1.5” stubs. I thought by unsweating I would save some pipe - what’s the downside? – David Dec 1 '20 at 20:18
  • and yes, I will have shut offs dedicated to each supply, the way it is right now, except for a double shut off for the 2 dishwashers. So, should I just unsweat and pit temporary Sharkbite fittings until the final counter and sink is in? – David Dec 1 '20 at 20:21
  • Ok, then cut it below the tee and then add a coupler and a enough pipe so you are not cramped against the bottom of the cabinet. Un-sweating is only getting you an inch or so and you want a little more anyways so why spend the time un-sweating. (do not paint yourself into a corner, especially when working with an open flame.)Temp shark-bites work and are good to have around but you can solder on a cooper cap for a fraction of the cost. – Alaska Man Dec 1 '20 at 20:55

My two cents:

  1. Do NOT use a flexible or clamp style drain fitting (I think you mean that when you say Fernco). I have never seen one that failed to leak. Glue an 1 1/2" male adapter to the trap arm (extending it first if necessary) and use a plastic slip-joint P-Trap and components with slip-joint fittings.
  2. Do NOT use any compression fittings on your copper supply pipe, solder male threaded adapters on and use valves that thread on. I have never seen a stop-valve that failed to fail and using threaded valves significantly simplifies the replacement job you will be doing in 10 years or so. Use the best quality 1/4 turn stop valves you can get your hands on, you may have to go to a plumbing shop (not big-box) ; pay whatever they cost.
  3. Do NOT attempt to "unsolder" copper fittings unless you: are experienced and also willing to cut the pipe back if you cant get a new fitting to slip on.
  4. DO dry-fit the sink, cobbling up something that positions it where it will approximately be once the cabinet is installed. If you end up needing to lower that drain you will want to do it before the cabinet and sink are in. (I know this was mentioned by someone else also, but you seemed dismissive of the concern).
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    Agreed on all points. Additionally, if drain height adjustment is needed, now would be a good time to open the wall around the drain and find out if there's really a vent and why it has several fittings in a row there. PVC DWV is easy to work with. Just don't get the glue on your hands or eyes (I wear safety glasses when I do it so I don't accidentally rub my face with it.) – Jeff Wheeler Dec 2 '20 at 11:16
  • Are there compression to thread adapters the OP could use to attach their replacement valves without having to sweat something to the pipe, or is the issue with the compression fitting itself? – ThreePhaseEel Dec 2 '20 at 13:18
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    My issue is particularly with valves with integrated compression fittings for attachment to the supply pipe. There is no standardized threading convention for the compression nut/ferrule attachment. The fact that recent manufacturers have utilized standard 5/8" comp. thread does not mean they always will, and over the years (decades actually) I have encountered odd threads there, and poorly toleranced threads, that would not satisfactorily allow installation of a new valve without cutting the pipe behind the ferrule (thereby shortening the already insufficient length present). – Jimmy Fix-it Dec 3 '20 at 5:16
  • @JimmyFix-it Thanks. (1) I actually cut back to just after that reducer so I will be able to glue another reducer. I'm sorry if I seemed dismissive of the drain (4). It's just I didn't have a sink then and from the specs, it looks like it would be a similar sink. Also, I intend to temporarily attach the old sink before counters are made and delivered in 2-3 weeks. I will rebuild the drain then - as I have to do this anyway for 2 dishwashers (used to be 1). One will connect to the garbage disposal and the other, I'm thinking, will connect to the second sink's slip joint with branch tailpiece. – David Dec 4 '20 at 17:33
  • @JimmyFix-it on #3, too late ;) I unsoldered it and glad I did, as I don't have a lot of pipe. I only had to cut off about 1/4 of pipe and it cleaned up nicely. I do have some experience and the pegs look great. I put Sharkbite caps on while the cabinet was being installed. – David Dec 4 '20 at 17:36

Plumbers prefer to use PEX today in new house construction. Read up on it on some YouTube videos, and then visit your Home Depot plumbing isle. They carry it. BTW, the transition between brass and PEX is made with shark bite fittings, so you might like the change. The total cost for tools and supplies may be $100 to $150, but you will be a PEX expert and never look back.

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