La Marzocco GS3 slow regular water leak through OPV - Page 2

Equipment doesn't work? Troubleshooting? If you're handy, members can help.
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Peppersass
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Joined: 15 years ago

#11: Post by Peppersass »

Ah. Your previous posts didn't say that the vacuum breaker leaks only when the machine is off and cooled down, not when it's hot. That's important.

I think the problem could be excessively high water pressure. If the water pressure at the GS/3 input is too high, it may be forcing the autofill valve to open slightly, allowing a small trickle of water to seep into the steam boiler. Eventually, the steam boiler overfills. The valve opening is probably small enough to keep the boiler pressure under the level required to close the vacuum breaker valve, so water leaks out through the valve into the drain box.

This doesn't happen when the machine is on because the vacuum breaker closes when the water gets hot enough to raise the pressure. Water could continue to leak very slowly into the steam boiler, but since you have the machine on for so short a time each day it never gets anywhere close to the point of overfilling. Also, the pressure inside the boiler when it's heated up is probably greater than the low pressure flow coming from the slightly open autofill valve. I'm not sure, but I think this would retard or stop the flow coming from the autofill valve. When the machine cools down, the pressure goes to zero and the steam boiler slowly fills up over the many hours between shutdown and the next morning.

I'm guessing that the first time the leak filled the drain box, you emptied the steam boiler. When you restarted the machine, the problem went away -- until the machine cooled down and the drain box got full. If you kept draining the steam boiler, you would never see any symptoms of the leak when the machine is hot. But if you turned on the machine without draining the steam boiler, you would probably see symptoms related to the steam boiler being overfilled -- like the steam gauge needle jumping around, limited or no steam capacity, water coming out of the steam wand, etc.

You must use a pressure regulator to reduce the input pressure to your GS/3. It's generally recommended to run espresso machines with no more than about 30 psi water pressure, which is about 2-3 BAR. They aren't designed for high-pressure input. There should be a water pressure regulator between the softening system and the machine, like the small black device on the far right of this photo, which I obtained from Chris Coffee:



House water pressures vary, but I know that some municipal water supplies can go as high as 100 psi. My well supply is set for 60 psi. If the house pressure is something like that, then it's likely too high for the GS/3.

The flow restrictor you mention might be acceptable. Is it intended for use with coffee machines? Is it adjustable? Does it have pressure gauge? If it's just a non-adjustable unit with no gauge, see if you can find out from Everpure what the output pressure is. If it's adjustable, you really need a gauge to set it. The regulator in the picture above is inexpensive and quite effective.

It's a good thing you did the vacuum breaker upgrade. Had you not done so, the water would have leaked all over the inside of the machine and would likely have gotten into the brain box and contaminated the logic board.

rajivsab (original poster)
Posts: 55
Joined: 9 years ago

#12: Post by rajivsab (original poster) »

I am going to install the 0.5 GPM flow restrictor and see what happens and if that does not work then I am going to install the pressure regulator. I will report back. Thank you for your help.

rajivsab (original poster)
Posts: 55
Joined: 9 years ago

#13: Post by rajivsab (original poster) »

Hi everyone. Back online to report status on issue above which I will close shortly. The issue was not water pressure rather #1 pointed out by the folks at LM:

-------- Original message --------
From: Solutions <Solutions@lamarzoccousa.com>
Date: 02/09/2015 4:51 PM (GMT-08:00)

There are essentially four different ways that your steam boiler can overfill (in order of likelihood with a plumbed machine);

1) Through the check valve (or valves depending on age of machine) on the hot water output line between the steam boiler and the hot water mix valve. This water supplies the hot water dispense with hot water, and if the check valve has failed, cold supply water will pass through the mix valve, past the check valve, and into the steam boiler.
2) Through the autofill solenoid passively, due to a worn solenoid plunger, or debris in the valve.
3) Through the autofill solenoid actively, due to a fault in the autofill electronic circuit. This is an obvious failure due to the fact that the pump and solenoid will be running non-stop and water will be exiting the machine with great authority.
4) Through the pre-heater tube if there is a failure of the copper inside the steam boiler. (this is the least likely cause, and usually occurs only in larger multi-group machines when the tube is broken during shipping. However, pin holes can be caused by particularly aggressive water)

Cause one is your most likely scenario. Current machines actually have two check valves inline on this tube, specifically to help solve this problem.

Cheers,
Chris

So I took it upon myself to cleaning both the valves, following the directions from my fellow Baristas: I disassembled the machine and cleaned both the valves in the line #1 noted above, in vinegar and a micro plastic brush. The valves are an amazing piece of metal crafted by genuises. A magnifying glass revealed the very small pieces of debris (1/20th the size of a grain of rice) that was lodged in the valve. After assembly the machine is back to normal - 100% operational. The vacuum breaker closes with a soft pop at 163 degrees. No leak from the vacuum breaker valve when the machine cools. Not a drop. Upon heatup of course a few drops and steam and crack and pop and hiss here and there. I am able to turn the machine on and off daily. I now have an upgraded vacuum breaker, brand new steam boiler o-rings on both sides. And cleaned up pipes on the right hand side. For future readers, it it is 100% brass part, don't bother ordering these expensive parts but try cleaning them first. Do not overtighten the nuts. i think I tightened them just right. No leaks upon re-assembly.

My best to you all and look forward to helping others who experience issues with their GS/3. Just contact me please. Peppersass. You rock! :mrgreen:

Thanks.

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Peppersass
Posts: 3690
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#14: Post by Peppersass »

Sorry for not catching that one. There have been posts about failure of the check valve on the hot water mixer causing a problem, and I knew that LM has added a second check valve in the line from the boiler to the mixer. In fact, after re-reading one of those posts I ordered that upgrade last week: two tubes and a check valve.

What I failed to do was connect that failure with your boiler overfill scenario. My bad!

If you don't have filters inline, you should add them. Typical setup would be:

Sediment Filter --> Softener --> Carbon Filter --> Pressure Regulator

(The expansion tank you see in the photo I posted is to compensate for fluctuations in pressure that are typical for well systems.)

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