Pasquini Livia 90 pumps water to drain after dispensing hot water

Equipment doesn't work? Troubleshooting? If you're handy, members can help.
findar
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Joined: 2 months ago

#1: Post by findar »

Recently acquired a Livia 90 and am trying to narrow down what is causing the unit to pump water through the overflow.

Currently, the unit can turn on, get to temp/pressure, and pour a shot as expected confirming the 3-way solenoid works properly.

When the unit however tries to dispense hot water and the motor comes on the water flows out immediately to the drain. My thought is that the 2-way solenoid is closed for some reason so the flow of the pump goes into the heat exchanger, causing it to overflow to the drain. I've confirmed it is coming out this way by monitoring which hose to the drain has water flow.

I've disassembled the OPV, soaked it in descaler which removed a noticeable amount of patina. Disassembled and cleaned the 2-way solenoid which had similar amounts. Confirmed the voltage going into the solenoid is 110 and the solenoid itself works by removing and testing with a screwdriver.

Is the only culprit at this point the control board?

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hankbates
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#2: Post by hankbates »

Since the control board seems to be working elsewhere, I would first look somewhere else.
When the pump runs it sends potentially 15bar water to the assembly where the boiler fill valve and OPV are located.
The 3way valve only opens when brewing, and it works properly.
If the boiler fill valve is plugged or closed, or the line is plugged. then the OPV should open and discharge to drain (or back to the reservoir, if the tubing is so arranged).
This is where I would start...
Some people rescue dogs and cats, I like to rescue Livias…

findar (original poster)
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Joined: 2 months ago

#3: Post by findar (original poster) »



So going with this diagram:

The OPV does not discharge into the blue line in any of the scenarios I've run into. The discharge comes from the yellow line(3 way solenoid) so I am assuming it's being fed from pressure in the Heat Exchanger since that's a closed vessel.

findar (original poster)
Posts: 8
Joined: 2 months ago

#4: Post by findar (original poster) »

When recording a test video to show the issue I noticed the pressure gauge dropping as it poured. This shouldn't occur since the backpressure from the orange line should close the OPV, correct? If so then I think that confirms a leak in the heat exchange.

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hankbates
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#5: Post by hankbates »

If you can brew (or better yet, backflush with blind disc) without raising boiler pressure, the heat exchanger is probably not broken.
I don't understand the piping coming out of the heat exchanger as shown in your photo: it appears to split and send to both the 3way valve and elsewhere? I can't find this option anywhere in the parts lists...
Perhaps a better photo of the top of the boiler would help.
Some people rescue dogs and cats, I like to rescue Livias…

findar (original poster)
Posts: 8
Joined: 2 months ago

#6: Post by findar (original poster) »

It only goes to the 3 way valve. The pressure stat is right there and probably makes it hard to see but my plumbing is exactly like the diagram you made elsewhere.

Here's a recording of the backflush:
Here is a recording of the core issue, water pump going straight to the drain after dispensing hot water:

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hankbates
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#7: Post by hankbates »

In the second video, if the refill water is just only going to drain, you will sooner or later have a boiler which is so empty the heating element will see air and burn out. Need to figure this out before too many more tests.
Wrong three way valve, or installed wrong? Its function is only to route water from the heat exchanger to the group when energized, when not, from the group to discharge...
If the three way valve is open from HEx to drain when not energized, the pump could be filling the boiler but also overpowering the spring loaded check valve in the OPV which usually only opens when the path is clear downstream.
Some people rescue dogs and cats, I like to rescue Livias…

findar (original poster)
Posts: 8
Joined: 2 months ago

#8: Post by findar (original poster) »

In all of my tests I shut the machine down immediately because of that concern and also because of the risk of hot water overflowing the basin. When turning it back on it seems to properly engage the pump and refill the boiler.

One thing I did notice is that when doing the backflush test the pressure drops. Is this expected? The path to the boiler should be otherwise blocked.

The 3 way valve comes into play after the water has left the heat exchange and since it only controls where the water flows (head or discharge), it is going to discharge since it is at rest. That seems to be working as expected because there is no leak when doing the backflush test(energized and no water coming out until brew turned off).

That leads me to the problem of the water going into the heat exchanger, so my thoughts on the possible culprit:

* The OPV backpressure valve from the heat exchange is not pressurized enough causing water flow to go that route
* The boiler fill solenoid is not being energized when the probes report low level of water (the pump engages as expected, and when turning machine it fills the boiler on so this feels less likely. This is next on my things to test with a voltmeter during operation just to remove it from suspicion)
* The heat exchange has a leak and pressure in the boiler is forcing water out (flow of water seems to match pump speed, so maybe not?)

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hankbates
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#9: Post by hankbates »

The three way valve controls only the flow into or out of the group head. When brew switch is on, the pump runs and it will open the "into" path. If the pump runs when the brew switch is off, the valve is only open between the group head and drain.
It should never connect the pump and heat exchanger to drain....
Its primary function is to eliminate the portafilter "sneeze" common in lever machines such as the La Pavoni.
Some people rescue dogs and cats, I like to rescue Livias…

findar (original poster)
Posts: 8
Joined: 2 months ago

#10: Post by findar (original poster) »

Ah then it sounds like the last owner installed the 3 way in reverse when they tried to repair it. I'll give that a try and see if it resolves the problem.