# OPV hose output diversion



## Stanic (Dec 12, 2015)

Hi, after dialing in, backflushing and other activities involving back flow through the OPV, I've been getting some foul smelling water in the water tank of miss silvia, also a very fine grit would collect on the bottom. Guessing that the culprit might be the backflow from the OPV, I've decided to divert the output of its hose to another vessel and see the effects. I've deep cleaned the machine yesterday and flushed half a litre of water through the boiler.

Wonder about the water quality in the tank after couple of days.


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## El carajillo (Mar 16, 2013)

Is this a one off? or does it happen frequently ? If a one off , did you flush plenty of water through after cleaning/ de-scaling including using the blind basket ? If not it is possible you flushed the boiler but there would be a residue left in the OPV. Do you use milk ? any sucked up wand and into boiler ?


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## Stanic (Dec 12, 2015)

El carajillo said:


> Is this a one off? or does it happen frequently ? If a one off , did you flush plenty of water through after cleaning/ de-scaling including using the blind basket ? If not it is possible you flushed the boiler but there would be a residue left in the OPV. Do you use milk ? any sucked up wand and into boiler ?


I've seen water coming out from the OPV hose regularly and was concerned about it for a long time

I've always flushed the OPV generously when descaling with water

I've had this problem before I started frothing milk regularly and I always make sure to keep the wand clean and flushed

When I make espresso within the 1g / 1s frame, I see water coming from the OPV hose


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## greymda (Oct 6, 2016)

water coming out the OPV is normal, especially when pressure set ~9 bars.


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## El carajillo (Mar 16, 2013)

As stated above it is a normal function BUT I suggest you use a P/F gauge to check the pressure at the brew head, this should be aprox 9 bar.

If it is too low this would allow water back to the tank when brewing using correctly ground coffee. If the coffee was too finely ground, this could be choking the basket and forcing the water through the OPV.

Check pressure at brew head and adjust if necessary. If the pressure is wrong it would be worth checking the OPV to make sure it is clean and there is no grounds/ scale specks preventing it closing correctly ( check the seat / seal)


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## greymda (Oct 6, 2016)

El carajillo said:


> As stated above it is a normal function BUT I suggest you use a P/F gauge to check the pressure at the brew head, this should be aprox 9 bar.
> 
> *If it is too low this would allow water back to the tank when brewing using correctly ground coffee.* If the coffee was too finely ground, this could be choking the basket and forcing the water through the OPV.
> 
> Check pressure at brew head and adjust if necessary. If the pressure is wrong it would be worth checking the OPV to make sure it is clean and there is no grounds/ scale specks preventing it closing correctly ( check the seat / seal)


so if i brew at 6 bar is it bad?


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## Stanic (Dec 12, 2015)

The OPV is set at 9 bar static, verified with PF measurement thermo/mano meter

After three coffees and some back-flushing today, there is around 200 ml of water in the jug, the espressos were very nice 

I'm glad I'm not mixing that water with the fresh one in the tank


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## El carajillo (Mar 16, 2013)

The excess flow back should only be from the pump, Ie circulating. It should not be contaminated.


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## El carajillo (Mar 16, 2013)

greymda, the normally accepted pressure for the majority of machines is accepted as 9 / 10 bar (non pressurised baskets)

Some members have experimented and find lesser pressures give a different nuance to the coffee.

What you are doing is not "bad", if you enjoy the coffee that is most important. I presume you must be grinding coarser , tamping harder to maintain the 25/ 30 sec guidelines for the pour.


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## Stanic (Dec 12, 2015)

El carajillo said:


> The excess flow back should only be from the pump, Ie circulating. It should not be contaminated.


I would think so

I'll do a smell test tomorrow..when I say foul smell I mean water smelling of something industrial, kind of boiler water  simply not fresh water without any smell at all


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## El carajillo (Mar 16, 2013)

Any colouring / mould in the flexible water pipes ? Remove clean disinfect ?


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## Stanic (Dec 12, 2015)

El carajillo said:


> Any colouring / mould in the flexible water pipes ? Remove clean disinfect ?


No, just the input hose is very slightly yellowish, but good tip! I'll take the cover off tomorrow to see how does it look like there in detail


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## Stanic (Dec 12, 2015)

the water collected from the OPV hose is clean and no smell..I'll probably have to dismantle and clean the input hose in the end


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