Home-Barista.com

Hi everybody,

after suspecting it and wondering for a long time, I got a pressure gauge to test the brew pressure of my machine (Rancilio Epoca) and found out that it is indeed way too high at 12.5 bar. So the logical next step is to bring it down to between 8.2 - 9 bar....

That being said it seems easier than to do. After looking over the machine for many weeks, I still haven't got a clue what an OPV or some device to change the brew pressure should look like in general, or on the Epoca in particular. And besides the screw for adjusting the boiler temperature, I cannot make out any other obvious screw either.

Can anybody help me or provide a picture of the piece of evidence in question? Or would it help if post some pics from the inside, so someone could comment on that?

Thank you very much !!

Thank you Dan for the pics and the diagram.

As to the pic, i cannot find such a device on my machine.

The diagram is pretty helpful though as I can locate the spot where the OPV should be. What i find there is a three way connection between the boiler, the pump, and the drip tray. What i cannot find is a nut that could be adjusted. All nuts are really big and solid, and none of them can be moved easily.

I put up some pics on coffeegeek, maybe you can comment on them (?).

Rancilio Epoca -- how to adjust the brew pressure?

The key thing is as Dan asks, does your Epoca have a rotary or vibe pump? The plumbed in version (rotary) has a OPV that looks like the picture below. The vibe OPV may or may not be the same.

n.b. this board won't upload an image directly. Check the Nuovaricambi.it site for an exploded Epoca parts diagram & a drawing of the OPV.

Thank you for your comments and suggestions and excuse when trespassing site policies -- maybe you might add the above p.s.-post to the FAQ file to make the point clearer.

Wookie, unfortunately you didn't leave the exact link. Following the link brings me to a page that doesn't seem to offer much. But i guess my machine has a vibration pump and not a rotary pump -- it is not the plumbed version but the tank version Epoca S1 /w tank. It is supposed to have independent heat exchangers though i am not sure what is meant by independent.

But here's a pic of the pump (sorry, i couldn't get a clear pic of the label on it -- it says: Ulka Italy, Model E Type EP5 120V 60Hz 1/1min. CI.A 41W)





Here are a few more pics. First the backside:



No idea, if my comments are helpful to the experts. On the right side you can the the Boiler Fill Solenoid (i guess), next to the left is the 3-way-connection i spoke of earlier, the third branch lies behind and leads to the drip tray. The brass loop right in front of the boiler connects to the pressure gauge in the front that measures the boiler pressure which will be adjusted by screw located in the black box.


The left side (left seen from the front):



That would be the 3-way-connection and the Boiler Fill Solenoid....


The right side:



This side is mostly electrics. The brass pipe in the background connects the adjusting box for the boiler pressure with the boiler.


The front side (for completeness):



The brass pipe on the right connects the 3-way-connection to the drip tray.


One more pic from above (front is left):



The screw located above and on the brewhead, which i mentioned before with a detail pic, can be seen on the left side between red electric cable and black insulated water tube. I have no idea what the function of this screw might be -- it looks almost like it might be possible to block the flow to the brew head or it might be related to the 3-way-solenoid valve under it.

The brass pipes in this picture are:
a.) in 12 o'clock direction: Boiler Fill Solenoid;
b.) 10 o'clock direction: hot water outlet;
c.) 2 o'clock direction: brew water, connects to the previous mentioned 3-way-connection;
d.) 3 o'clock direction: boiler pressure gauge;
e.) 4 o'clock direction: boiler pressure adjustment (black box);
f.) 7 o'clock direction: steam wand


Hmm.... did forget something? Hmm, yes, on the last pic there's a rather bright, big nut to see on the right side. This thing is directly on the boiler and looks like some safety valve but doesn't look like it could be twisted in either way. It also lacks the shape for attaching any tool.

Hm, thanks again and sorry to bother you.

Hi Yapit - Certainly everything Dan says is correct and the most important thing he is saying is

"Keep in mind however that since you have a vibration pump, this will only affect the maximum pressure when pulling ristrettos. In other words, the actual brew pressure is the lesser of the puck's resistance, the pump's capacity at a given flow rate, and the expansion valve setting."

Another poster on this site (and I wish I could give him due credit) also described the most correct method of measuring the OPV setting by bleeding off a chosen flowrate (his was 2 oz. in 25 seconds which I certainly agree with) by means of a needle valve tee'ed into the pressure gage line. I would also add that you need to seal the metal-to-metal contact surface between the basket and the portafilter (o-ring, rubber band, double layer of saran wrap, etc.).

The difference between zero flow at the portafilter and 2 oz per 25 seconds is 0.5 bar on my Silvia but yours may be different (nice machine you got there). With zero flow from the portafilter, you should also be able to measure the flow from the OPV back to the tank simply by putting the hose in a glass measuring cup (use a 2-cupper). Time an 8 ounce flow and do the math/conversion to cc/minute. The performance curve for the E5 pump you have is also somewhere on this site but for starters, you should be measuring about 110 cc/min in the OPV line if your 12.5 bar is correct. That 110 cc/min represents my interpretation of the E5 pump performance curve and as Ulka doesn't really give any explanation for their dashed lines, it becomes a little subjective.

Anyway, hope all is well in the cup and, if I were you, I would not make any rash adjustments.

Good Luck,

Eric S.