Isomac Espresso Machine Upgrade - OPV Solution?

Equipment doesn't work? Troubleshooting? If you're handy, members can help.

#1: Post by PoorAfficionado »

Hi all, long time lurker,

A machine has just come to my hands, an ISOMAC Maverick. I like the looks and the feel, nonetheless, I have an issue with pressure.

Whenever the grind is fine enough, so that the flow is right (and also the coffee has some nice crema), the pressure shows to be 13-15 bar, which is huge (and shows in the taste).

If the grind is thick enough to keep the pressure up to 9 bar max, the coffee comes with 0 crema.

Whenever I pull shots, I open slightly (there is a screw control) the steam wand, this way, the machine is sprouting warm water and the pressure can be controlled down to 8-12 bar.

I am seeing promotional videos of this machine being used online, I don't see this situation.
  • Is that the case, where a cold water OPV would help?
  • Which one are you proposing?
  • What else should I be buying, other than the valve per se (tubes, sealant, adaptors etc)?
Thank you all guys!

Team HB

#2: Post by JRising »

There are several models called "Maverick" if I'm not mistaken, but they're predominantly just knock offs of the basic Italian SBDU often referred to as Imat/Lelit/Mokita types. You should open the top of the machine and see what, if anything, it is using as an OPV. And if nothing, look around the layout to see where you could fit one of the little T-fittings with an adjustable OPV in one end (that Lelit used to use) or Whether an elbow could be replaced with a tee so that you could put a smallish OPV on that.
If you post a picture of the inside, we might be able to suggest something...

Also see the posts by Strikeraj, he's very deep in the Imat version of a very similar machine.

Faema Eurostar Ambassador Rebuild and Mod Journey

In Striker's photos you can see the adjustable OPV is mounted directly to the outlet of the pump.

PoorAfficionado (original poster)

#3: Post by PoorAfficionado (original poster) »

thank you for taking the time to answer. I have opened the machine and there is no OPV valve.

Is there a reason for having a smallish vs a bigger OPV Valve? What is the best possible solution? that is my model.

Team HB

#4: Post by JRising »

Interesting. It looks like it doesn't even have a 3-way brew valve.
Any chance you could post a picture of it with the top off?

The larger a valve is, the more surface area there is on its valve-face, so the longer it should last before it begins to leak internally. Additionally, the littlest of OPVs that Lelit used to use, even they don't use anymore because they're just too small to work with once they've gotten the least bit sticky. Attempting to turn their adjusting thread crumbles the valve to bits rather than turning just the threaded body. Larger valves can hold together better and remain adjustable and repairable longer. For example, I've probably repaired more than 200 Rancilio Silvia OPVs, and only had to replace the complete valve maybe 5 times over the past 15 years. Big, sturdy OPV (but too big to fit anywhere in your little Maverick).

The only reason to use smaller valves is to make the machine cheap so it can compete with the other entry-level/wedding present grade products in its price range, and to get something that will fit. If you can get your hands on one like you see in Striker's Machine, that should connect perfectly to your pump. ... -valve-opv
The one that Lelit used to use... Not great.

It's possible that the Isomac branded one could be made to fit somewhere in your machine. ... -valve-opv

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#5: Post by stefano65 »

The Maverick should have the style of OPV integrated with the steam valve 0154 sku
you could potentially remove the guts from it (mushrooms and spring)
leave it fully open then add another one on line (we sell several ones and so do other vendors)
but I don't recall the volume available in your particular model the location will be a challenge inside your casing.
Stefano Cremonesi
Stefano's Espresso Care
Repairs & sales from Oregon.

PoorAfficionado (original poster)

#6: Post by PoorAfficionado (original poster) »

here is the inside of the machine. Something that looks like an OPV is the regulator for the steam wand and it is after the hot "pot".

Team HB

#7: Post by JRising »

That's not a regulator for the steam wand, there is no "regulator" for any steam wand, the needle valve operating as the actual steam valve regulates the flow of steam (somewhat) to the steam wand.
That OPV is completely the opposite outlet from that tee-fitting, it has nothing to do with the steam wand side of that boiler outlet, it is functioning as an OPV to limit the maximum pressure in the brew circuit (the little brew valve on a spring will be lighter, thus it would effectively be the expansion valve).

In good news, it's definitely an OPV and it looks adjustable to me, examine it more closely. If it's still adjustable, it should be good enough. If it seems seized closed and un-adjustable, be gentle with it. Let us know how it goes.

PoorAfficionado (original poster)

#8: Post by PoorAfficionado (original poster) »

Hey, I appreciate the time taken to check my configuration.

There is no adapter, therefore this OPV is non-adjustable. Let's not forget, that this is on the warm side. So there is nothing in the cold side, that I could be using to reduce pressure.

Ideas are welcome.

User avatar
Team HB

#9: Post by Jake_G »

You can adjust the OPV as John suggested. OPV does not have to be on the cold side. Just pop the hose off, loosen the fitting a little bit, and then replace the hose.
LMWDP #704

Team HB

#10: Post by JRising »

PoorAfficionado wrote: There is no adapter, therefore this OPV is non-adjustable. Let's not forget, that this is on the warm side. So there is nothing in the cold side, that I could be using to reduce pressure.