Valentina brew pressure adjustment - Page 2

#11: Post by **shadowfax** » June 23rd, 2005, 11:22 am

Well, there are bound to be some layout differences. Mine is not even the same model as yours... it's the Levetta version, AKA BFC Junior Plus. I went back and looked at your pictures, heh. those things are ridiculously big!

Anyway, I think your boiler is brass. Copper would just turn green in a hurry. I have a brass boiler too, it's just nickel plated, which is exciting to me, because it really helps resist scaling. Looks like you have the Ulka EX5 pump, though. I think Dan has the same version as you, only his pump is the EP5, which is the same but with a plastic barrel rather than the brass one.

you should plumb her in and get a rotary vane pump

#12: Post by HB » June 23rd, 2005, 10:16 pm

shadowfax wrote:Anyway, I think your boiler is brass. Copper would just turn green in a hurry. I have a brass boiler too, it's just nickel plated, which is exciting to me, because it really helps resist scaling.

Minor correction. Both are copper, and newer models are nickel plated (link).

June 24th, 2005, 3:58 pm

shadowfax wrote: you should plumb her in and get a rotary vane pump

What advantages is there in a rotary vane pump? instead of the one I have?

James

#14: Post by **shadowfax** » June 24th, 2005, 8:50 pm

smooth pressure delivery. vibratory pumps deliver pulsing pressure, which is one reason unbuffered manometers tend to jump around when monitoring brew pressure.

You can actually see the vibrations in the brewing if you have a naked portafilter, sometimes. It's sort of a sinusoidal contour along the cone flow of the espresso extraction. Sometimes I can even see it in my shot pictures... I don't really know what taste advantages this has, other than what Chris Tacy and some others say; I have never used a machine with a vane pump.

#15: Post by HB » June 24th, 2005, 9:06 pm

I'll be lazy and excerpt some of my observations from The Buyer's Guide to the La Spaziale S1:

Some espresso aficionados claim to taste a difference at various pressures. If you are inclined to tweak the pressure to discover for yourself, it is easy to do so with a rotary pump since it has a built-in bypass valve that allows you to set the pressure directly. That is, unlike vibration pumps, which put out their maximum pressure for a given resistance and rely on an expansion valve for pressure regulation, a rotary pump puts out the same pressure independent of the flow rate. In a commercial environment, one rotary pump may service several groups, plus it doesn't require the pauses that a vibration pump must have (about one minute maximum before resting for one minute).
...

One other advantage of rotary pumps is they are quieter than vibration pumps, especially when the pump is external to the machine under cabinet as is often the case in commercial setups.

The last point is the big selling point -- rotary pumps are much, much quieter than vibration pumps.

#16: Post by **another_jim** » June 25th, 2005, 1:32 am

HB wrote:That is, unlike vibration pumps, which put out their maximum pressure for a given resistance and rely on an expansion valve for pressure regulation, a rotary pump puts out the same pressure independent of the flow rate.

Andy pointed out this was technically wrong; although you'd need to get 5 groups and the boiler refill going before you'd notice.

If the long rumored vibe-sized rotary makes its debut in the LM, and then becomes available for other single groupers; it'll probably show flow to volume limits similar to vibes.

#17: Post by **Bradley Allen** » July 9th, 2005, 7:16 pm

shadowfax wrote:just in case the original poster is interested, here's a shot of where it is on my valentina... Just beside the Gicar flowmeter thingy.

Hey there mister shadowfax. It is time. Enough is enough. Operating the La Valentina Levetta way over 9 BAR (as shipped) is just killin' me. Argh! I'd love to understand why someone would sell them that way by default. But I digress.

So I have the back off and can now see inside. I feel so nerdy!... but I'm not sure how I would reach that 12mm adjustment nut which is trying to hide behind the Gicar water refill circuit.

Did you remove anything else in your photo before adjusting? Or did you use a special, magical wrench? The depth of field in your photo makes it seem right next to the Gicar, where from my vantage point at home it appears beside... yet just a little bit below it - and nearly out of reach.

#18: Post by **shadowfax** » July 10th, 2005, 12:53 am

If you loosen the mounts (I think with an allen wrench) of the Gicar flowmeter, you can push it out a little bit to make the OPV more accessible. other than that, you do have to do wrist acrobatics to get your 12 mm wrench around that thing. just keep working at it. good luck!

#19: Post by **Bradley Allen** » July 10th, 2005, 4:10 am

shadowfax wrote:If you loosen the mounts (I think with an allen wrench) of the Gicar flowmeter, you can push it out a little bit to make the OPV more acessible. other than that, you do have to do wrist acrobatics to get youer 12 mm wrench around that thing. just keep working at it. good luck!

Thanks! I took another look at it and yeah, I'll just take the Allen wrench to the Gicar... it should be easy then.

#20: Post by **Bradley Allen** » July 11th, 2005, 8:39 pm

Okay. Here I am at the threshold. I've got a few questions/observations...

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.

This is with the machine on "at rest" (not lifting the levetta to pull a shot or operating the steam wand, etc.) ... it just does this over and over. Flow and ebb. I was hoping that the machine would just hang out at .9 with some sense of stability without the green light having to kick in every few seconds. Maybe this is a separate issue altogether but I'm still curious what's going on here.

Maybe I'm not turning the valve enough? Maybe I'm turning it in the wrong direction? Maybe I'm turning the wrong thing? Either way, I'm feeling pretty clue-less right now.