La Marzocco GS3 massive water leak through OPV [resolved]

Equipment doesn't work? Troubleshooting? If you're handy, members can help.
A2chromepeacock
Posts: 148
Joined: 17 years ago

#1: Post by A2chromepeacock »

Hi all. This is a new post to describe a sudden problem with my plumbed-in GS3, it's possible causes, and upcoming fix.

The other morning, I heard from the kitchen a sudden rush of water and steam spitting. Quick inspection showed a very large amount of water spewing from the OPV (not the brass expansion valve) into the drip tray. I'm not plumbed out--if I hadn't been home this would have caused a major flood. Gulp. It looked just like the pictures from mjbelcher in his post UPDATE - More than La Marzocco GS3 Refill Tank Malfunction. The pump wasn't running. If I activated the tea water, the leak immediately stopped, but resumed when the tea water was turned off. Even with the machine off, water continued to fill the drain tray at line pressure. I shut down the water supply into the machine, and it (of course) stopped leaking.

This issue has been described before--both by mjbelcher as noted above and by peppersass. In Matt's case, he determined his steam boiler over-filled due to a sensor issue with the pour-over tank mode. In peppersass's case, it was an electrical issue with the steam boiler water level probe as described in page 2 of La Marzocco GS/3 buyer needs help.

Neither of those things were my problem--mine is turning out to be related to the complex plumbing on the right side of the machine. With a cold machine and drained steam boiler, I first unscrewed the copper pipe that fills the steam boiler (entering the boiler at 3 o'clock; "H" on the photo below from gs3cafe.com) and turned the water supply back on--checking to see if the solenoid "I" was stuck open. No water flowed through, so that wasn't the reason for the overfilled steam boiler. Next I unscrewed copper pipe "J" exiting the steam boiler that normally takes hot water to the tea water mixing valve. This time, water flowed freely out of that copper pipe, at line pressure. The problem, as understood currently, is that the one-way check valve (the second "J", just next to the tea water mixing valve) is faulty or stuck open, allowing water to flow the wrong way backwards into the steam boiler--it overfills and then vents out the OPV causing my sudden and massive leak.



The service guys at Chris Coffee have been great in helping me diagnose the problem, and they're sending me a new check valve. Here's a picture that I sent them of my machine, that they labeled and sent back noting the location of the faulty valve:



I'll keep this thread updated once the new valve arrives and I install it (anyone have any great ideas about how to get that thing unscrewed? It is pretty tough to access). I'd be interested to know if anyone else has had this problem. Needless to say, I'm now quite interested in plumbing out and installing a flood detection/water shutoff device.

Best,
Derek
Derek
LMWDP #139

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yellow_speedster
Posts: 48
Joined: 14 years ago

#2: Post by yellow_speedster »

I have had 2 machines back with this same problem. In both machines I put in a extra solenoid in the hot water outlet line to prevent this overfilling in the future.
The most easy way to get to the one-way is to remove all lines on this side. Otherwise it is impossible to reach it.

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Peppersass
Posts: 3690
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#3: Post by Peppersass »

Yikes. Back when I had the flow rate problems on my first GS/3, LM suggested it might be a bad check valve in the tea water mixing unit. I stared at that thing for hours wondering how I could get a wrench to the check valves on the back side. Luckily, Chris Coffee steered me in a different direction and I never had to face that problem.

I'm sure yellow_speedster is right -- you'll have to remove most if not all of the pipes on that side of the machine to get at the check valve. Do let us know how that goes.

I'm wondering if it's just a faulty check valve or scale deposits jammed it open. What's the hardness level of your water? Are you using a softening system? Have you done any descaling?

A2chromepeacock (original poster)
Posts: 148
Joined: 17 years ago

#4: Post by A2chromepeacock (original poster) »

Yeah, I think it'll be major surgery to get at that check valve. I'm not looking forward to it, but I'll discuss it with Chris's folks this week.

I am concerned that it's scale formation. When I removed the outlet pipe from the steam boiler, there was a small amount of greenish scale buildup at the inlet. Very small amount, but still...wouldn't take much to jam up a check valve, I don't think.

I'm using a cation exchange softener from Chris, followed by a 10 micron carbon block filter setup. It had done a very good job of softening my water, as detailed here: Testing the water produced by the "Chris Coffee" water treatment system

But I haven't checked the hardness in a few months--it may be that the cartridges exhausted faster than I thought they would--they've been in place for 9 months with ~2-3 shot per day usage. One americano, one shot, one latte.

I was going to ask in a separate post about descaling, to keep this one focused on the issue mentioned....I think I'll write that other post now!
Derek
LMWDP #139

A2chromepeacock (original poster)
Posts: 148
Joined: 17 years ago

#5: Post by A2chromepeacock (original poster) »

The good news: A new check valve (as pointed out in the above pictures) is on the way from Chris Coffee.

The bad news (quoting from their email to me): "Unfortunately we have never had to replace the check valve yet on the GS3's so [we] do not have much guidance to give." :shock:

The slightly encouraging news: the folks at Chris Coffee service have a demo machine that they're going to work on, to see what the best method is to actually get at the check valve--they'll put together some instructions for me (a good tinkerer but a bit afraid of such a major surgery). As mentioned by several posters above, it doesn't look easy.

I'll keep the thread updated, with pictures once I get the new check valve in the mail.
Derek
LMWDP #139

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networkcrasher
Posts: 606
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#6: Post by networkcrasher »

Best advice I could give is not to super tighten up the self sealing connections at reassembly time. The ones that seal on their own have little cones after the threads that are the first thing to go into the nut. If you torque them too much, they can literally split the nut.

I put a flood mitigation system on my GS3 just for situations like this. I'm plumbed in and out, but still... It's called the Leak Controller, and i have a sensor under my counter by the filters and another sensor in parallel that sits under the GS.

A2chromepeacock (original poster)
Posts: 148
Joined: 17 years ago

#7: Post by A2chromepeacock (original poster) »

networkcrasher wrote:I put a flood mitigation system on my GS3 just for situations like this.
thanks...and ordered :)
Derek
LMWDP #139

A2chromepeacock (original poster)
Posts: 148
Joined: 17 years ago

#8: Post by A2chromepeacock (original poster) »

Next step before the actual surgery...the directions! The guys at Chris Coffee service took apart a GS3 they have there to figure out how to do the repair. It's a neat trick (at least to me) how they get the valve out--they leave most of the right side piping in situ and back the mixing valve out. If anyone's interested, I can post their worded directions, but a picture tells most of the story. They sent this one to me:



A nasty summer flu bug has the project delayed a day or two, but gory intra-op pictures to follow. I also plan to install the new longer braided hose during the repair to address the well-described vibration issues.
Derek
LMWDP #139

A2chromepeacock (original poster)
Posts: 148
Joined: 17 years ago

#9: Post by A2chromepeacock (original poster) »

Update with pictures. Here's the starting photo, with the boiler exit pipe disconnected already (arrow). I'm using the photo sent to me by Chris's service (the one on my previous post) as a guide.



And here's after removing the connections and coil from the mixing block:

And here's the badger removed from the machine, with an arrow pointing to the faulty check valve (it better be faulty, at this point!!!)


For completeness, a shot of the right side of the machine with the mixing block assembly removed:


Next step will have to wait a day until I can get to my friend's house who has a vice to hold the block for check valve removal and replacement.
Derek
LMWDP #139

A2chromepeacock (original poster)
Posts: 148
Joined: 17 years ago

#10: Post by A2chromepeacock (original poster) »

Apologies for the delay in updating this thread--but it's good news in the end.

With the mixing block removed, it got locked into a vice for check valve removal:


I installed the new check valve as shown here, with the old one in the foreground:


The problem was that the new check valve (the mid-portion, non-threaded) is about 3-4mm wider than the original. This ended up being a royal pain because the copper pipe leading away from it had to be bent (not easy to get it right, took forever) to be the correct length to attach back to the steam boiler.

I put everything carefully back together, took the opportunity to install the longer braided hose, and fired it back up. No leaks, no problems, and I'm back in espresso again!

Many, many thanks to the repair/service guys at Chris Coffee--I quite literally couldn't have done it without them.
Derek
LMWDP #139

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