La Marzocco Linea - Autofill Problem

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Tiger22
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Joined: 14 years ago

#1: Post by Tiger22 »

A new problem has arisen with the steam-boiler autofill on my Linea EE 1-group and I was wondering if anyone could offer any insight as to what the problem might be.

For the last couple of days, after my machine has been fully warmed up, the autofill has kicked in when the steam boiler level dropped but it hasn't stopped filling when the water level had risen back up to the set level, and instead overfilled the boiler (water everywhere had to switch it all off!).

Initially I pulled the autofill probe and it had some corrosion on it which I cleaned off before re-inserting into the steam boiler.

After draining the steam boiler below the usual level I switch the machine back on. The autofill kicks in as expected and then stops at the correct level. However about 30 minutes later the autofill starts again and again doesn't stop, overfilling the boiler. This cycle has repeated a few times now.

Can anyone suggest what the problem might be? I'm guessing the problem lies in one of 3 areas - the probe and attachment, the solenoid valve, or the control box, but I'm not good enough with electrics to know how to diagnose this one.

Many thanks,
Tony

leozava
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#2: Post by leozava »

if you unplug the wire to the autofill and ground it to the boiler does it keep filling??

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erics
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#3: Post by erics »

I would clean the probe again but this time use some silicone carbide 400 grit paper. Make sure that the female spades are tight at both ends of the probe wire.

The proper water level with this Linea is with the sight glass at the 2/3'rds level - grain of salt. Yes, you can always "jury rig" a ground wire attachment to the connection at the water level probe and, if any fill occurs after this, it is very likely a control box issue.

The age and serial number of the machine might help also. All of the above assumes you have not changed your water filtration/regulation system.
Skål,

Eric S.
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E-mail: erics at rcn dot com

Tiger22 (original poster)
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Joined: 14 years ago

#4: Post by Tiger22 (original poster) »

Hi Eric & leozava,

Thanks for your replies,

I bought my Linea 1EE new in 1999 with a manufacturing date of 11/98. I have not changed water filtration type recently (Claris Ultra).

I did clean the probe thoroughly with grit paper - it is sparkly new. Connections all tight.

When I detach the wire from the probe the boiler starts filling as expected. When I short the wire to the boiler it stops filling, as expected.

Just to clarify, are you saying I should leave the wire continually shorted to ground and if the autofill kicks in at any point after this then it's the control box that needs replacing? The current control box is about 4.5 years old.

Thanks,
Tony

leozava
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#5: Post by leozava »

i would try leaving it shorted and seeing what it does. just keep an eye on the water level so you dont ruin your element

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erics
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#6: Post by erics »

Here would be the EXACT steps to follow. There is NO NEED for heat so no need to turn the switch past position 1.

a. Drain some water from the steam boiler such that you know the autofill will kick in when the machine is turned on.
b. With everything normally connected, turn the machine on to position 1 and let the steam boiler autofill.
c. Does it reach about 2/3 of the sight glass?
d. Turn machine off, unplug it, and make a SECURE connection between the wire to the probe and ground. This might require a little wiring connection knowledge but is relatively easy to do.
e. Plug her in and turn the machine on to Position 1.

At this point and for "hours on end", nothing else should happen. You may want to repeat this test to verify the lack of pump operation when the probe lead is grounded.

HB member jpboyt is very knowledgeable of these control boards and may offer additional insight - search.php?keywords=&terms=all&author=j ... t=0&ch=300
Skål,

Eric S.
http://users.rcn.com/erics/
E-mail: erics at rcn dot com

jpboyt
Posts: 220
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#7: Post by jpboyt »

Hello,
I wouldn't suspect the control box. If the machine passes the test that Eric laid out for you, I would suspect a steam boiler that needs descaling. The probe signal needs to make it through the water and the scale to reach the boiler which is at ground potential. With the boiler full and hot, I would measure the resistance between the unconnected probe and the exterior of the tank. If that value is too high the control will see it as a boiler with a low water level. Cleaning the probe only removes the scale from one side of the probe to tank via water circuit. Or you may need to ship me the machine to me for long, extremely long term evaluation.
Got a Super Jolly that needs a play mate. It's getting tired of baby sitting Mr. Coffee...
jpboyt