Connecting CPVC to galvanized? CPVC or PEX?

Question

I want to tackle replacing the water lines to the kitchen sink myself and have a couple of questions, how do I connect the new CPVC lines to the old galvanized lines at the point where I will be cutting out the old galvanized line? I don't see any fittings made for this purpose ( I may have missed it ) and I cannot find any answers on google.

I might end up going with PEX pipes, if so, is it the same as far as how to connect to galvanized lines goes?

Michael Herr · Answer

@Nick Harrington

The fitting that @Jeremy Pace recommended will not work for connecting to a cut section of galvanized like you are asking.

Those fittings work on practically every type of modern supply pipe, except galvanized, which requires a threaded transition.

You must go back to a thread and use a threaded fitting.

You can likely reduce to 1/2", and me (and most here) would reccomend pex over cpvc.

Consider replacing all of the galvanized: cry once.

I proactively replace galvanized with PEX in every single-family I buy.

Jeremy Pace · Answer

@Nick Harrington

There are reducers that you can use.  I would recommend against using a threaded fitting, because it would mean that you could have to successfully remove whatever fitting was previously threaded ... it will be faster and less hassle (in my opinion) to cut the pipe where you want to and de-burr it, and add the compression fitting.

In all honesty, if you plan it out correctly, it won't take much effort to simply replace all the galvanized pipe in the house, starting right at the meter.  galvanized pipe rusts/crusts inward first, so you'll have poor water pressure and hard/gross water over time anyway.

Joshua D. · Answer

Are you sure you want to keep the galvanized? I just replaced all the galvanized in our house with Pex and it was well worth the hassle.

You should be able to take the transition question to your local hardware store, and they can show you exactly what you need. it will be much simpler than telling you online.

My guess is that there will be about 4 different ways of doing what you want done.  Do the one that makes the most sense to you.

If your planning on doing live in rehabs for a while I would buy the Pex tools now. its well worth it.

Steve Babiak · Answer

Good advice there - get rid of all galvanized when you are already into doing significant plumbing work. You can readily run PEX to bypass all existing galvanized, and that will modernize your plumbing and solve lots of silly problems at the same time.

Jassem A. · Answer

I was doing some plumbing this past weekend connecting CPVC to cast iron and the 3/4" CPVC compression fittings will fit around the 1/2" iron pipe.

I don't think the sharkbites or the white plastic compression fittings will work though just the CPVC compression fittings.

Here's a picture of it:

They are $3.92

Jesse Freeman · Answer

@Nick HarringtonTo make the transition properly (to Universal Plumbing Code) you have to use a dialectic union to make that transition however you will have to solder a pex or cpvc adapter into the dialectic union. However to avoid having to solder you can just get a Pex X Female Iron Pipe Adapter (Or using a Male Iron pip adapter and a galvanized coupling.) With my experience I would highly recommend avoiding using shark bite fittings at all costs because I have seen several blow apart and flood entire houses.

As far as pex verses CPVC I would recommend pex for a couple reasons 1). Pex was designed to be very resiliant (you can freeze the pipes 2 or 3 times before it will burst and if you catch it before it does freeze that many times you can heat up the pipe and it will return to it's original form.2). if you use too much glue for the CPVC it will actually keep welding the plastic and can get too thin to the point of burst pipes. (This happened to a hotel near me where the builder used too much glue on almost all the fittings and now they are ripping out all the cpvc pipes in the whole hotel.)3). Pex is much easier and quicker to run.This has just been from my experience as a plumber. Hopefully it helps and will save you some head ache in the future.

http://www.homedepot.com/p/SharkBite-1-2-in-Brass-...)

Mike Baker · Answer

Good rule of thumb on PEX is that you can run 2-3 fixtures off a 1/2 inch line. Meaning run 3/4 fro he main run and then branch off to the fixtures. Keep in mind as well that there are many kinds of PEX. I prefer Uponor (used to be wirsbo). Reason for the preference is that the crimp ring on Uponor spends all of its time compressing the tube to the fitting, since it has a "memory", whereas other PEX fittings only crimp the ring to the tube and that's it. Research it, and as I always say, Don't be cheap! Get a good PEX.

Also, @Michael Herr is absolutely correct. You have to go from the threaded fittings, and YES, replace it from the meter to the rest of the house. If you only replace chunks you will get junk clogging your fixtures because any work you do on the system will only cut the inner rust in the pipes loose.

Lastly, take the aerators off your sinks when you finish and run the faucets. If you run them for a few minutes without the aerators it will kick all the junk out and not clog the aerator. Spin it back on and you just saved yourself a lot of headache.

Bryan C. · Answer

The new PEX is awesome because its fairly cheap, easy to install and less chance of vandalism to steal the copper!

Keith Belzner · Answer

As far as reducing the size you can reduce to each fixture but the "main " line needs to stay as large as possible. So if its 3/4 now feeding more than 2 or 3 fixtures you cant drop it to 1/2 for them.

Ex. The cold line feeds 2 sinks and a toilet at 3/4 line but drops to 1/2 right ar each fixture you cant go back to the meter and run all 1/2 to those same fixtues. To much pressure loss if all are on. Also cpvc has a different od than pvc just a fyi.

Jeff B. · Answer

Watch out with older Pex and newer PEX 1/2 there measurement standard changed.I am out but make sure it is the same OD Outside diameter.  Pex switched the measurement from OD to ID or inside diameter or vice versa.  Confirm with plumbing pro.

Connecting CPVC to galvanized? CPVC or PEX?

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