La Marzocco GS/3: Here's how to connect water main braided line to 3/8" OD John Guest/push to connect tubing

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#1: Post by rktcyntst »

This post is to help future owners plumb their GS3 using the included braided water line to their water main coming from 3/8" OD John Guest type tubing. Not really anything to discuss, but this worked for me. I got frustrated trying to find an answer that wasn't buried in a gabby thread. I hope this helps someone (probably my future self).

MPT, FPT, CP, NPTF, adaptor, reducer, coupling... lots of plumbing terms to make this overly complicated for a non-plumber to answer the question I ran into this afternoon: "What the heck do I need to connect the GS3's braided hose end to my 3/8" OD John Guest (JG) tubing?!?!"

I've got my water setup so that it tees off the cold water feed of my kitchen sink into 3/8" OD JG tubing. That goes into my filter, then to my water regulator, and then leaves me with 3/8" OD tubing end needing to connect to the GS3's braided water hose.

If you haven't connected your braided hose to your GS3 yet, but plan to, note that the ends of the braided line are NOT the same size. I found this out the hard way. One end connects to the GS3 pump. The other end natively connects to 3/8" Compression Fitting.

To connect it to 3/8" OD tubing, I used this:

GS3 hose --> 3/8" ID x 1/4" FIP coupling --> JG connector --> JG hose

GS3 hose --> 3/8" ID x 1/4" FIP coupling = ... 410?NCNI-5

JG Connector = ... /300753461

There it is. Go forth, and brew!

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#2: Post by charlesaf3 »

Note: I do a lot of plumbing. The ideal is to not have any John Guest fittings in your house... If you are going to an angle stop, why not just keep on with 3/8 braided?

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#3: Post by Peppersass »

I respectfully disagree that the ideal is to have no JG fittings in your house.

I wouldn't use JG for most permanent plumbing applications, but they're perfect for plumbing in an espresso machine. Without them, it would be quite difficult to install the filters, softeners, regulators, check valves, flushing circuit and cutoff valves required for most espresso machine installations, and the installation would lack flexibility for the almost inevitable changes we home baristas tend to make over time. Here's what my filter/softener setup looked at one time:

Then I changed it to this:

Now the two regulators are gone and I have one upstairs in the cabinet under the machine:

The space in the cabinet is very tight and I doubt very much that I could have installed permanent pipes in there without removing everything in the cabinet (including a Lazy Susan.)

I've had quite a few JG fittings in my setup for about 12 years and have had no problems with leaks. The key is to use the proper tool to cut the ends of the tubing flat and insert the tubing fully into the fitting. Always re-cut the end after removing from the fitting.

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#4: Post by charlesaf3 »

I come at this from a plumbers/contractors perspective. Regular plumbing is, if anything, much easier to install than John Guest. And it won't leak on you. For your pictures in particular, I could do that in half the time in Pex that I could in JG or other push fittings.

John Guest fittings are very DIY in the worst sense of the word to me. But I spend a lot of my life fixing and avoiding leaks and water damage, so it skews my perspective.

As a landlord, I would not allow them in a place I own because of the possibility of disaster. Too many rotted sink cabinet bases from leaking diy plumbing (of all sorts of flavors).

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#5: Post by CaptPat »

The OP was exactly what I was looking for as I'm replumbing my GS3 in a new house. :D
Duct tape can't fix stupid but it can muffle the sound.

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#6: Post by PeetsFan »

CaptPat wrote:The OP was exactly what I was looking for as I'm replumbing my GS3 in a new house.
Some advice:
1) If you use this plastic piping, using 3/8" John Guest.
2) To be clear: That means, "Use John Guest." That's an actual brand, not the El Crapo Brand stuff that Home Depot sometimes sells. If you can't find the material at Home Depot, try or any number of actual plumbing suppliers.
3) The OP didn't show you enough. You need to make a drawing from Sink to Machine. End-to-end.
4) John Guest tubing does not bend, although it does flex. Use JG right-angle fittings. put that into your drawing. You can see that I went with two large-radius bends. I decided it was better to have the large bends than to put in three right-angle, press-fit connectors. And, I'm lazy.
5) I used an in-line water filter. There are two parts: Carbon filter ("the water filter") and a water softener. I'm probably going to remove the water softener; I don't need it.
6) After the second water filter, you put in a T fitting because when you add a filter cartridge, you need to flush it. You want the black carbon goop to flush into a bucket and not into your La Marzocco.
7) You can buy a water pressure gauge from Amazon for about $25. You can put it on your T-fitting to measure water pressure so that you can be sure you aren't going to blow up your machine.
8) Draining the water is harder than providing the water. The incoming water is under pressure. It will go up/down/left/right. But draining water only goes downhill. Imagine my frustration when I finally got the drain connected... and no flow at all. So for now, I drain into a bucket, and I'm going to buy something called a "Condensate Pump" with a one-way valve, which will pump the water into my drain.
9) I have a Ring Alarm. They sell a two-pack water leak detector that's cheap. I put one under my espresso machine and another under my sink, so if this John Guest leaks, I'll get an alarm on my phone.
10) Under your kitchen sink, I replaced the cold water inlet valve with a two-output valve. Each can be shut off separately. You want shut off valves all over. I have the one under my sink, then right before the filters, then two after the filters.
I would be happy to share more of my experience with you. Was it worth it? Definitely.

Here's my setup so far. I removed the gauge because I don't want to keep it under continuous pressure.You see two outlets. One goes into the espresso machine and the other will eventually go into a small glass rinser. For now, I use it to flush out the carbon filter and I attached my pressure gauge there to make sure I was under 6 bars of incoming line pressure.