# OPV hose question



## greymda (Oct 6, 2016)

from my understanding, when we brew coffee, some water should come thru the group head and make coffee and some water should go back into the water tank thru a separate hose?

the fact is, i don't see water coming back into the tank on my Classic.

is it the way it should be?


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## timmyjj21 (May 10, 2015)

Sounds like your OPV needs checking. Do you get water coming through with a blank basket in place?


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## El carajillo (Mar 16, 2013)

greymda said:


> from my understanding, when we brew coffee, some water should come thru the group head and make coffee and some water should go back into the water tank thru a separate hose?
> 
> the fact is, i don't see water coming back into the tank on my Classic.
> 
> is it the way it should be?


Only if the brewing pressure exceeds the OPV setting pressure


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## greymda (Oct 6, 2016)

timmyjj21 said:


> Sounds like your OPV needs checking. Do you get water coming through with a blank basket in place?


i don't have a blank basket, so i improvised using a plastic pack to block the water coming out the portafilter (but it didn't worked really well, as a little water still came through). i see only water drops from the OPV hose, not a fluid flow... is this a problem?


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## Jumbo Ratty (Jan 12, 2015)

I could be wrong but here goes anyway.

The pump isnt going to be an over engineered item, so would imagine its only capable of producing the max pressure of 15bar.

The gaggia classic leaves the factory with the OPV valve set for 15bar.

Even with a blind basket in the portafilter the pump pressure wouldnt exceed what the OPV is set to, hence little or no returned water.

IF the OPV valve was set to a lower rating, say 9 bar then the pump would exceed that pressure by 6 bar with a blind basket in and 6 bars worth of water would exit through the corresponding hose.

Now someone tear that to bits


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## timmyjj21 (May 10, 2015)

Well, the ulkla pump should be moving a lot more water than a few drops. Even with a bit coming through with your portafilter blocking method I would have expected a flow through the OPV.

If the group head is blocked off with a blank basket, then all the water would be diverted through the OPV, assuming the pump makes the pressure go above the OPV's threshold.

So...

Maybe the OPV is not opening, be it scale buildup or incorrect adjustment.

Or maybe the pump is on the way out.

You can google 'Gaggia classic ulkla pump flow' or something similar to get an idea of expected flow rates...oh look! Here's one...

http://www.gaggiausersgroup.com/index.php?topic=231.0

And this may help diagnostics without any equipment, but I strongly recommend you consider a blank basket just for backflushing and general cleaning plus consider a pressure gauge portafilter, there are several being passed around the forum members.


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## timmyjj21 (May 10, 2015)

And JumboRatty might be correct. I keep forgetting about factory preset pressure since it's the first thing I diddle with my refurbs so never bother to check how much water was being diverted!


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## greymda (Oct 6, 2016)

so i should try to turn 270 degrees anti-clockwise (thus pressure would be ~9 bars) and try blocking it again and see if i got water flowing from the OPV hose?


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## timmyjj21 (May 10, 2015)

Definitely get a blank basket first!

Doing it blind may work, but it's not a precise adjustment and I've known some machines to need much more or less than the 270 degrees, but it's a good starting point.


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## greymda (Oct 6, 2016)

okay, so i did it blindly, i.e. no pressure gauge. i've ringed all the services around me, all staring at me (got it from their voice).

so, i've went for 60-65ml of water from the opv in 15 seconds.

at default settings not getting any water at all from the opv.

turned 270 degrees, water started flowing, but getting ~35ml in 40 secs.

turned another 90 - ~45ml. hmm, getting there.

turned another 180 and only then i am getting steady 60ml in 15 secs. check several times. around 60-62ml.

put all back together and tried to brew an espresso. i see water coming out the opv, i see espresso coming out the pf, but it's quicker than before. so if till the opv tune in i was getting ~45ml from 17g coffee in 30 secs, i now get ~30ml from the same 17g coffee and same 30 secs.

any advice would be gladly appreciated. cheers from Moldova!


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