# Gaggia OPV adjustment



## fly3k (Jun 20, 2020)

Has anyone successfully lowered the pressure on a Gaggia Evolution? I've had a look at the safety valve above the tank but after turning it I didn't read any change in the 15 bar pressure it's putting out on the meter I'm using on the Portafilter.

I've seen a replacement part on eBay for £27 which I think would allow some adjustability and a YouTube video using parts from the classic but I wondered if anyone has had any luck with the stock parts.

Hopefully you knowledgeable forum members can steer me in the right direction.

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## MrShades (Jul 29, 2009)

fly3k said:


> Has anyone successfully lowered the pressure on a Gaggia Evolution? I've had a look at the safety valve above the tank but after turning it I didn't read any change in the 15 bar pressure it's putting out on the meter I'm using on the Portafilter.
> 
> I've seen a replacement part on eBay for £27 which I think would allow some adjustability and a YouTube video using parts from the classic but I wondered if anyone has had any luck with the stock parts.
> 
> ...


Can you post a picture of the valve on the top of the pump?

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## fly3k (Jun 20, 2020)

MrShades said:


> Can you post a picture of the valve on the top of the pump?
> 
> Sent from my iPhone using Tapatalk


I don't have an internal photo to hand but this is the one from an eBay listing of a spare part which I hope might help.










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## MrShades (Jul 29, 2009)

Does it have a slotted internal adjustment screw - like you can see in the end of this one? Is that what you're turning? If so, I'd assume that loosening it would/should reduce the pressure - and increase the amount of water that leaves the valve via the pipe connected to that side of it. Keep loosing it a few turns and see what difference (if any) it makes. The valve cap, that is held in place with an internal spring (the adjustment compresses the spring, or loosens it) may have "stuck" to the bottom of the valve with scale or similar.... so you may have to remove that adjustment screw completely, take the spring out and then see what's in the bottom of the valve body (and see if it moves or can be moved / removed with a small screwdriver or similar).

Just a word of caution - this is pure speculation based on my experience of other Gaggia OPVs - I've never taken one of those apart!


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## fly3k (Jun 20, 2020)

MrShades said:


> Does it have a slotted internal adjustment screw - like you can see in the end of this one? Is that what you're turning? If so, I'd assume that loosening it would/should reduce the pressure - and increase the amount of water that leaves the valve via the pipe connected to that side of it. Keep loosing it a few turns and see what difference (if any) it makes. The valve cap, that is held in place with an internal spring (the adjustment compresses the spring, or loosens it) may have "stuck" to the bottom of the valve with scale or similar.... so you may have to remove that adjustment screw completely, take the spring out and then see what's in the bottom of the valve body (and see if it moves or can be moved / removed with a small screwdriver or similar).
> Just a word of caution - this is pure speculation based on my experience of other Gaggia OPVs - I've never taken one of those apart!


Yes it does have that slotted screw and that was what I tried adjusting. I was a bit fearful of messing it up by undoing too much but I did a few turns. I'll get it apart again and try taking it completely apart to see if there is any scale or spring inside.

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## fly3k (Jun 20, 2020)

MrShades said:


> Does it have a slotted internal adjustment screw - like you can see in the end of this one? Is that what you're turning? If so, I'd assume that loosening it would/should reduce the pressure - and increase the amount of water that leaves the valve via the pipe connected to that side of it. Keep loosing it a few turns and see what difference (if any) it makes. The valve cap, that is held in place with an internal spring (the adjustment compresses the spring, or loosens it) may have "stuck" to the bottom of the valve with scale or similar.... so you may have to remove that adjustment screw completely, take the spring out and then see what's in the bottom of the valve body (and see if it moves or can be moved / removed with a small screwdriver or similar).
> Just a word of caution - this is pure speculation based on my experience of other Gaggia OPVs - I've never taken one of those apart!


So just had it apart again and adjusted that screw. It was pretty much unscrewed as far as it would go and there is something that stops it coming all the way out like a collar. I can screw it right the way in and you can hear a spring in there. Pressure remained at 14 bar with the screw all the way out and all the way in. Took a photo of the piece as below.

























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## MrShades (Jul 29, 2009)

Leave it undone as much as possible and then try throwing it in a vat of citric acid for a few hours and see if that helps. I'm guessing that the valve is just stuck closed.

When you run the machine, does ANY water come out of the pipe connected to that side of the valve at all, I suspect not.


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## fly3k (Jun 20, 2020)

MrShades said:


> Leave it undone as much as possible and then try throwing it in a vat of citric acid for a few hours and see if that helps. I'm guessing that the valve is just stuck closed.
> When you run the machine, does ANY water come out of the pipe connected to that side of the valve at all, I suspect not.


Nothing comes out at all and I thought it probably should given that the basket end is sealed with the pressure gauge. I left it all apart as I wondered if another idea would come up so will go soak it in some citric acid.

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## MrShades (Jul 29, 2009)

fly3k said:


> Nothing comes out at all and I thought it probably should given that the basket end is sealed with the pressure gauge. I left it all apart as I wondered if another idea would come up so will go soak it in some citric acid.
> 
> Sent from my iPhone using Tapatalk


 After - or during - the soaking in citric, some "percussive maintenance" may help loosen it... 😉


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## phario (May 7, 2017)

I'll ask a bit of a stupid question.

Are you sure the OPV valve on the Evolution is adjustable?

My impression was that it isn't and you need to use a separate adjustable OPV.

http://coffeegeek.com/forums/espresso/machinemods/436367


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## fly3k (Jun 20, 2020)

MrShades said:


> After - or during - the soaking in citric, some "percussive maintenance" may help loosen it...


I've given it a soak in hot citric acid and taken out and adjusted the screw and allowed a further soak or two. I have a percussion hammer which might be the right key 

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## MrShades (Jul 29, 2009)

phario said:


> I'll ask a bit of a stupid question.
> 
> Are you sure the OPV valve on the Evolution is adjustable?
> 
> ...


 No, as I said before - not entirely sure, but logic states that if there's a spring inside there holding a valve closed, and an inner nut with a slot in it that moves in and out when you turn it (to loosen or tighten the preload on the spring) - which all looks/sounds very similar to the normal adjustable Classic valve (though pump mounted rather than boiler mounted, and a slotted nut rather than a hex) then turning that slotted nut will adjust the OPV pressure.

Logic could well be foiled though, as it may be that the valve is simply welded shut or otherwise not functioning - either way, it sounds like it's doing pretty much nothing right now.


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## fly3k (Jun 20, 2020)

MrShades said:


> No, as I said before - not entirely sure, but logic states that if there's a spring inside there holding a valve closed, and an inner nut with a slot in it that moves in and out when you turn it (to loosen or tighten the preload on the spring) - which all looks/sounds very similar to the normal adjustable Classic valve (though pump mounted rather than boiler mounted, and a slotted nut rather than a hex) then turning that slotted nut will adjust the OPV pressure.
> Logic could well be foiled though, as it may be that the valve is simply welded shut or otherwise not functioning - either way, it sounds like it's doing pretty much nothing right now.


I would have thought as you say that something would come out the other end when the pressure is at 15 bar and that it would be liquid so I would notice it. Unless it is set to only happen at a much higher pressure. I'm wondering if I was to apply some force down the pipe with something blunt and a hammer it might loosen anything that is stuck? Anyway still soaking for now

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## fly3k (Jun 20, 2020)

I managed to push down from the other end and felt the resistance of the spring valve. Now on the loosest setting I'm getting 14 bar and water running out the OPV. All the way in I get 15 bar and no water from it.

I think we can say that it isn't possible to adjust less than that and I'd need the parts from the YouTube video or the eBay option. So next question. Will 9 bars make much difference to my shots?


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## MrShades (Jul 29, 2009)

It might be worth you looking at the new plastic OPV that is used on the Classic 2019 / Classic Pro (they're about £12). I'm guessing that the screw thread is the same on top of the pump - though your output pipe (to the boiler) may (or may not) work on the long plastic nipple on the Classic OPV.

It might be an easier swap - for testing purposes... and whilst this one is also fixed at 12ish bar, you can remove the spring and replace it with one of my spring kits for 9 bar or 6.5 bar etc - an extra tenner.

Yes, the alternative is to swap the manifold on the boiler to an original Classic brass OPV but they're like £40 each

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## Blue_Cafe (Jun 22, 2020)

These Gaggia machines don't have "OPV's" they have safety valves.

If you want pressure regulation, either tee off the pump outlet with a separate valve (easy enough) or hack the manifold inlet with a modified GC inlet valve. (Both options mentioned above)

Leave the system safety valves well alone would be my advice.


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## fly3k (Jun 20, 2020)

I've bought this part off eBay and was hoping there might be some form of instructions provided. I have messaged the seller but wondered if anyone had any ideas as to where it goes. I figure that it should go between the current safety valve and the boiler but wasn't too sure where it should drain out of the OPV if that's the case?

Any thoughts gratefully received.

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## MrShades (Jul 29, 2009)

You'll probably need to cut the water delivery pipe - from pump to boiler - but you'll have to be certain that the ends are tightly fixed into that T piece.

You'll then need some additional silicone tubing to connect to the output of the OPV, to route the 'spare' water back into the tank.

In my experience, these valves need to be almost fully extended in order to provide 9bar - and at that point the spring in them is so loose that they dump all of your steam pressure out of the OPV too. Just be warned.

Good luck!


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## FelixRT (Sep 21, 2020)

MrShades said:


> It might be worth you looking at the new plastic OPV that is used on the Classic 2019 / Classic Pro (they're about £12). I'm guessing that the screw thread is the same on top of the pump - though your output pipe (to the boiler) may (or may not) work on the long plastic nipple on the Classic OPV.
> 
> It might be an easier swap - for testing purposes... and whilst this one is also fixed at 12ish bar, you can remove the spring and replace it with one of my spring kits for 9 bar or 6.5 bar etc - an extra tenner.
> 
> ...


 Where I can buy those springs? I think is a easy mod and maybe help me to achieve better shots!


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## fly3k (Jun 20, 2020)

MrShades said:


> You'll probably need to cut the water delivery pipe - from pump to boiler - but you'll have to be certain that the ends are tightly fixed into that T piece.
> 
> You'll then need some additional silicone tubing to connect to the output of the OPV, to route the 'spare' water back into the tank.
> 
> ...


 So I got the valve fitted and with the valve as tight as it goes I get about 7.5 to 8 bar. Any looser it's about 5 bars. I emailed the seller to see if there was a problem and he said that this OPV isn't adjustable.

It pulls a better shot but I get a lot of water running back in the tank off the OPV now and I probably need to explore my grind size and tamping again as it's probably too fine now and causing the flow to mainly go out the OPV instead of through the group. I'm going to try and add a little something like a plastic washer to the OPV to increase the pressure back up a bit. I'm not losing any pressure off the steam wand which is a bonus.


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## Blue_Cafe (Jun 22, 2020)

fly3k said:


> So I got the valve fitted and with the valve as tight as it goes I get about 7.5 to 8 bar. Any looser it's about 5 bars. I emailed the seller to see if there was a problem and he said that this OPV isn't adjustable.
> 
> It pulls a better shot but I get a lot of water running back in the tank off the OPV now and I probably need to explore my grind size and tamping again as it's probably too fine now and causing the flow to mainly go out the OPV instead of through the group. I'm going to try and add a little something like a plastic washer to the OPV to increase the pressure back up a bit. I'm not losing any pressure off the steam wand which is a bonus.


 Pictures?


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## phario (May 7, 2017)

@fly3k maybe a dumb question, but did you not just get this one from shock_waves_shop? That one is fully adjustable from 8-14bar.

Is the one you bought not the same? Can the central cylinder not be disassembled, yielding an inner spring with an adjustable bolt?


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## fly3k (Jun 20, 2020)

phario said:


> @fly3k maybe a dumb question, but did you not just get this one from shock_waves_shop? That one is fully adjustable from 8-14bar.
> 
> Is the one you bought not the same? Can the central cylinder not be disassembled, yielding an inner spring with an adjustable bolt?


 That's the one I ordered. It unscrews but there is just a spring and seal inside. Nothing adjustable.


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## fly3k (Jun 20, 2020)

Blue_Cafe said:


> Pictures?


 I'll take some when I take I apart and put some washers in the OPV


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## phario (May 7, 2017)

fly3k said:


> That's the one I ordered. It unscrews but there is just a spring and seal inside. Nothing adjustable.


 What is holding the spring in? The way the OPV works, the spring needs to be held under tension. Once the fluid exceeds a certain pressure, the spring compresses, letting water flow out. So your spring needs to be held at the start and end points. An adjustable OPV allows you to move one of these two locations. Compressing the spring lowers the pressure while keeping it uncompressed elevates the pressure. http://www.espressomyespresso.com/opv.html

So I'm super confused about what you wrote then. As you said:



> I emailed the seller to see if there was a problem and he said that this OPV isn't adjustable.


 On the ad it is clearly written:



> Fully adjustable from around 7bar to 14bar.


 So...

*Edit:* Oh, I think these OPVs are adjusted via the exterior bolts.


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## Blue_Cafe (Jun 22, 2020)

^good post.

Get this sorted because this is actually the correct way to control pressures in these machines (imho anyways) and i am excited to see somebody do it right


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## fly3k (Jun 20, 2020)

Update time. Here is a photo of the OPV fitted. There are no adjustable bolts on the OPV but after talking to the seller you can adjust slightly by loosening the thread near the hose end. I added a small piece of plastic behind the valve before the spring and put the OPV back together. Pressure was a little higher than I wanted so I loosened the thread a bit and got the pressure to 10 bar on the pressure gauge. Pulled a shot with no issues.


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## phario (May 7, 2017)

What a beautifully clean Evolution!

Yellow/green ptfe tubing? Looks great. Where did you source that from?


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## Blue_Cafe (Jun 22, 2020)

Finally.

An OPV that is "done" safely and correctly.

Well done OP. Looks great.


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## fly3k (Jun 20, 2020)

phario said:


> What a beautifully clean Evolution!
> 
> Yellow/green ptfe tubing? Looks great. Where did you source that from?


 Thanks! I was impressed how clean it was when I got it. The group and portafilter not so much but I've given them a good clean up too. The tubing was something my dad happened to have lying around in his garage and it works well so far.


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## fly3k (Jun 20, 2020)

Blue_Cafe said:


> Finally.
> 
> An OPV that is "done" safely and correctly.
> 
> Well done OP. Looks great.


 Yes the original safety valve is still there and in-line so if all else fails that will kick in and save the day. Now to use up some of my staler beans and buy some more fresh ones


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