Valentina brew pressure adjustment - Page 2

[AndyS]

First, I want to double confirm that the OPV valve is 'lefty loosey, righty tighty' (left lowers the pressure, right increases the pressure). I've cranked to the left and to the right, and either way this is what happens:

The needle on the manometer rises to 1.2, then it slowly falls to just under 1.0, then the green light switches on, then the needle rises to 1.2, and then it slowly falls again. Rinse, repeat.

The manometer readings that you're looking at are boiler pressure (AKA "service boiler pressure.") Service boiler pressure is controlled by the pressurestat.

The OPV valve is a different animal. It limits extraction pressure in the heat exchanger/brew head loop. You can't control the service boiler pressure with the OPV. So stop trying.

[HB]

Don't confuse brew pressure (adjust OPV / expansion valve) and boiler pressure (adjust pressurestat). Valentina / Levetta doesn't have a brew pressure gauge, you will need a gauge attached to the portafilter.

PS: Counter-clockwise (left) = looser = more water escapes = lower brew pressure.

[shadowfax]

that's the BREW pressure adjustment, not the BOILER pressure adjustment, Einstein!

:p

You need to be putting a cup to the pressure runoff (which is the OTHER tube feeding into the rear reservoir, putting a blind filter in, and running the pump for 30 seconds (remember, 30 seconds AFTER the preinfusion, you can tell when preinfusion ends, the pump will bog), and checking the volume that comes out. anything less than 2 oz, and you need to loosen (counter-clockwise). anything over 2.5, and you need to tighten (clockwise).

You will have to locate your Sirai Pressurestat if you want to adjust boiler pressure. Why would you? it's set just about right. anything less than .9, and you will get crap steam. anything more than 1.2 and you will have no time to pause after flushing. If you try to make the window smaller (say .9-1.0), your boiler cycles will be very short and the heating element will turn on and off, on and off, on and off, a WHOLE LOT. this will ultimately wear your pressurestat and heating element out much faster.

[cannonfodder]

The needle on the manometer rises to 1.2, then it slowly falls to just under 1.0, then the green light switches on, then the needle rises to 1.2, and then it slowly falls again. Rinse, repeat.

Sounds like you are adjusting the P-Stat (boiler temperature adjustment). The OPV should have no interaction with your pressure stat which is what it sounds like you are describing. The OPV only comes into play when the pump is pressurizing to brew.

[cannonfodder]

I did not see the next page before I posted, sorry for the redundancy.

[shadowfax]

I did not see the next page before I posted, sorry for the redundancy.

Haha, poor Bradley, we hit him 3 in a row across 5 minutes, and now you... That's pretty funny.

It's OK, Bradley, we've all gotten our variables mixed up before... gotta be able to laugh about it

[Bradley Allen]

Haha, poor Bradley, we hit him 3 in a row across 5 minutes, and now you... That's pretty funny.

It's OK, Bradley, we've all gotten our variables mixed up before... gotta be able to laugh about it

Oh, I'm laughing it up. And will be for years. Via the power of the Internet, future generations will be able to look back on this time as: "Oh, that's when that no-nuthin' Bradley Allen guy first looked under the hood of an espresso machine... and was frightened by his own distorted reflection in the boiler".

Thanks for setting me straight, folks. Sometimes a dog pile is the best way to learn. Seriously. I appreciate it.

[shadowfax]

I wish I could see my reflection in my boiler...

[Bradley Allen]

I wish I could see my reflection in my boiler...

It was a joke. I can't really see my reflection in it. In other words, "afraid of nothing".

[Bradley Allen]

You need to be putting a cup to the pressure runoff (which is the OTHER tube feeding into the rear reservoir, putting a blind filter in, and running the pump for 30 seconds (remember, 30 seconds AFTER the preinfusion, you can tell when preinfusion ends, the pump will bog), and checking the volume that comes out. anything less than 2 oz, and you need to loosen (counter-clockwise). anything over 2.5, and you need to tighten (clockwise).

Okay. I had to go out of town.. now I'm back. The machine is still apart and I have time to play.

Again. I'm confused. The pressure runoff is the rubber tube that's connected to the OPV, and normally goes into the rear reservoir, right? Okay. Fine. I pulled that out and put a cup underneath it. I opened the lever, let it run for 30 seconds after pre-infusion and no water came out of it. Weird.

So back to doing what I think I think I should be doing (PLEASE correct me in detail how I'm doing it wrong)...

I have a blank portafilter in the group. And a liquid measuring cup under where the waste water comes out (below the solenoid in the lower group).

I open the lever. I let it run for 30 secs. after pre-infusion. Then I close the lever and measure the water in the measuring cup.

It comes out to about 1.5 oz. of water. I turn the OPV counter-clockwise some more. Rinse. Repeat. It's still under 2 oz. of water.

I think I'm going insane.

You will have to locate your Sirai Pressurestat if you want to adjust boiler pressure. Why would you? it's set just about right. anything less than .9, and you will get crap steam. anything more than 1.2 and you will have no time to pause after flushing. If you try to make the window smaller (say .9-1.0), your boiler cycles will be very short and the heating element will turn on and off, on and off, on and off, a WHOLE LOT. this will ultimately wear your pressurestat and heating element out much faster.

I didn't try adjusting the Sirai Pressurestat. All I did was loosen the hex screw that mounted it to the machine so I could get at the OPV behind it. It's cycling between .9 - 1.2 (which, as you say, should be normal). It just appears to be doing it a WHOLE LOT. I'm not sure what's up with that.

[HB]

Again. I'm confused. The pressure runoff is the rubber tube that's connected to the OPV, and normally goes into the rear reservoir, right? Okay. Fine. I pulled that out and put a cup underneath it. I opened the lever, let it run for 30 seconds after pre-infusion and no water came out of it. Weird.

Sorry, I have to ask. Did you have the blind basket in place? The OPV will only open if the pressure exceeds its current setting. If no water comes out of the OPV with the pump running at its maximum, the valve is either set very high, clogged, or otherwise stuck shut.

[Bradley Allen]

Yes. I had the blind basket in place. Is this desired? Should I just pack a double basket with grounds instead?

I ran it again a few times since my last post. The OPV is now loosened so far counter-clockwise that the rubber tube is beginning to twist. Not too much to cut off flow, but still, this can't be right.

I get consistent approx. 1.5 oz of waste water no matter what I do. And just little drips maybe from the tube connected to the OPV (which always has water in it, though it doesn't come out. I guess a vaccuum has formed in the line). Geez, should I start siphoning and measure the contents I spit out or something?

Not enough when combined to add up to 2 oz. It's the 'no matter what I do' part that has me worried. Obviously, I'm doing something very wrong.

Complete and utter idiot-proof details, please. Like, step 1: Turn machine on.

[shadowfax]

1.5 oz from where? If you're putting the cup under the backflush runoff, that will get you absolutely nowhere. that's spitting out the volume of the water between where the lever cuts off and the shower screen. basically, the volume of the preinfusion chamber and some tubing in the grouphead. This volume probably is 1.5 oz, and you'd have to re-cast your E61 to get that flush volume to change.

you need to be measuring what comes out of your overflow tube, which is the shorter tube feeding back into the tank. If you aren't getting anything from this with a backflush disk, then you've got a problem. If the pump is still going (it bogs down but continues turning), then you have overflow occurring SOMEWHERE. if it's not out of the overflow tube, then it sounds like your pump is broken or you have a leak somewhere else along the line.

Anyway, I don't have the time or inclination to take my machine apart and run through this again myself. Since you have your machine in pieces, why don't you tell us in your desired level of detail what you are doing, what your results are at each point, and perhaps we can help from there.

[HB]

We definitely have a failure to communicate. Jim Schulman's Adjusting vibe pump pressure on HX machines explains the mechanics, including the diagram below:

(reproduced with permission)

You should be measuring the water exiting the over-pressure valve, which you've clearly identified. The tubing at the end of the OPV may twist when you adjust, but it's easy to remove, untwist, and replace.

[Bradley Allen]

1.5 oz from where? If you're putting the cup under the backflush runoff, that will get you absolutely nowhere. that's spitting out the volume of the water between where the lever cuts off and the shower screen. basically, the volume of the preinfusion chamber and some tubing in the grouphead. This volume probably is 1.5 oz, and you'd have to re-cast your E61 to get that flush volume to change.

Well. That settles that, then. Whoopsie.

you need to be measuring what comes out of your overflow tube, which is the shorter tube feeding back into the tank. If you aren't getting anything from this with a backflush disk, then you've got a problem. If the pump is still going (it bogs down but continues turning), then you have overflow occurring SOMEWHERE. if it's not out of the overflow tube, then it sounds like your pump is broken or you have a leak somewhere else along the line.

Forging ahead... and re-casting myself in a new light, here's a pic of what I think is the overflow tube, which is connected to the OPV adjustment valve:



You can kinda see a bit of water trapped inside the tube. When I pull a shot a little bit of water dribbles out of it. But nowhere near 1-2 ounces.

I don't think the pump is broken. It doesn't run constantly or not at all. It turns on (I think) during pre-infusion and then turns off during extraction. And I don't see a leak. I've handled the machine with kid gloves. Or at least with clean hands.

Now, before I took the hood off the machine, I was making espresso just fine. Okay. It came out too hot/bitter, and looking back, I was viewing the boiler pressure gauge and freaking out over the 1.2 BAR readings. I thought anything over 9 BAR on the meter had to be too hot. But obviously, I didn't understand HX machines. So based on what I've read here, I thought that if I lowered the brew pressure, controlled by the OPV valve (no gauge for that), it wouldn't come out as hot, and I'd have a better extraction.

I'm explaining all of this to make sure I'm on the same page with you guys.

Should I just go out and buy a fancy pressure gauge? If so, sign me up. I want to do this right.

But right now, I'm not sure where to go from here. I can guess at where I had the OPV adjustment valve cranked, put everything back and pretend I didn't touch a thing. Everything will still work. And I'll still be able to extract espresso. It'll just be too hot/bitter. And I feel that would be a waste of what I imagine to be a fine machine.

[Bradley Allen]

You should be measuring the water exiting the over-pressure valve, which you've clearly identified. The tubing at the end of the OPV may twist when you adjust, but it's easy to remove, untwist, and replace.

The failure to communicate has been all mine. So none of this "we" stuff. You guys have been amazing. Thank you.

[HB]

But right now, I'm not sure where to go from here. I can guess at where I had the OPV adjustment valve cranked, put everything back and pretend I didn't touch a thing. Everything will still work. And I'll still be able to extract espresso. It'll just be too hot/bitter.

I'm not sure where you are either.

Keep in mind that the OPV determines the maximum pressure during the extraction; the puck determines the minimum. So the OPV not opening isn't an issue for double espressos since the pump flow rate works out to around 9 bar anyway (as explained earlier in the thread). If you're pulling ristrettos (or "accidental ristrettos" as Jim sometimes calls them), it's another story. Then the OPV determines the maximum pressure by venting excess water back to the tank, thereby reducing the overall pressure.

If you don't see a full flow of water coming out of the tubing leading from the OPV when a blind basket is in place, then something's not right. Either the adjustment nut is torqued in way too tight (which compresses the spring), or there's some obstruction.

Should I just go out and buy a fancy pressure gauge? If so, sign me up. I want to do this right.

Although the "runoff method" is a decent estimate, I prefer to measure with a pressure portafilter or install a gauge. Understandably many home baristas don't want to shell out money for an infrequently used tool, but that's what I'd do. Bob explained how you can build your own with standard hardware, quoted below:

It seems to me that if your going to measure brew pressure and make adjustments, then you need to know the exact pressure that you have while pulling a shot. Most portafilter gauges measure only the static pressure at the brew head when the by-pass valve has opened. That is not the pressure you are getting when you are brewing espresso. The attached photo is a simple mod I made to the gauge I bought from Chris Coffee. I can adjust the needle valve to allow precisly 2 oz of water to flow in 25 seconds while reading the pressure. On my machine, the resulting pressure is 8 bar, as seen in the inset.

Bob



here it is in use:

PS: If your espresso is too hot, check your flushing routine as described in How I Stopped Worrying and Learned to Love HXs.

[Bradley Allen]

After giving it another try (now that I learned the error of my ways) the OPV was cranked way too far to the right. I don't recall being that aggressive with it. I think it just shipped that way. But either way, I was able to get the runoff tube to expell 2 oz. of water at 30 seconds.

I put everything back and now I'm a happy camper. Thank you. Yay!

Gee, after all was said and done, that was... pretty easy.