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CharcoalRoaster
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Posted on 05/23/2015 6:46 AM
I performed my regular backflush on my Gaggia this morning and was just curious. Outside of the portafilter and perhaps the group head (to a certain drgree) how does coffee oil/residue make it into the inner parts of an espresso machine? Hence, the need to backflush regularly?

I thought because of the pressure there would be no suction or anything like that to pull coffee oils back into the innards, but I would take a guess that I'm probably wrong on at least one level ThumbsUp
 
turtle
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Posted on 05/23/2015 8:57 AM
When the pull is over the pressure backs up through the 3 way valve and out the waste spigot into the tray. Along with the pressure coffee and grounds can also travel along for the ride.

This explains it pretty well (click the next link at the top to go through the entire operation of a 3 way valve)

www.frcndigital.c...way/2.html
Edited by allenb on 05/23/2015 9:06 AM
Mick - "Drinking in life one cup at a time"
"I'd rather be roasting coffee"

Roaster 1: San Franciscan SF-1
Roaster 2: Hottop B-2K+
Roaster 3: 2 kilo Chinese drum
Grinders: Mazzer Major - Forte BG (x3)
Pour over: Hario - Bee House - Chemex - Kalita - Bodum
Drip: Bunn CWTF15-1 & CW15-TC (commercials)
Espresso: Pasquini Livia 90 auto
Vacuum: Cona - Bodum
Press: Frieling - Bodum Colombia
 
ginny
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Posted on 05/23/2015 3:23 PM
the pressure works both ways...

pushes in and out.

much like all in nature.


ginny


cool
 
CharcoalRoaster
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Posted on 05/23/2015 8:03 PM
Figured it had to be something like that. Thanks ThumbsUp
 
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