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Adjusting vibe pump pressure on HX machines

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Discussions > Espresso > Machines > Adjusting vibe...

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strugs
Senior Member

Joined: 21 Jul 2003
Posts: 658
Location: Vancouver, Canada
Expertise: I live coffee

Espresso: Vincent Wega (Wega Lyra)
Grinder: Jules (Mazzer Mini)
Vac Pot: Hario TCA-5
Drip: Tray
Roaster: 49th and/or Intelly

Posted Sun Nov 21, 2004, 2:17pm Subject: Re: Adjusting vibe pump pressure on HX machines

Sure - the Lyra is just the North American name for the Mininova. Maybe email it to me if it is not too big of a file. Thanks. I just re-read your post from yesterday about adjusting the safety valve. From what I recall, the safety valve is a copper valve that sits on top of th boiler. I don't think it is adjustable though, so you must be fiddling with the 2nd OPV. I just took a pic of the guts of my machione. I'll post it in a few minutes.

- Sean

syd
Senior Member

Joined: 30 Jun 2004
Posts: 436
Location: Melbourne
Expertise: I like coffee

Espresso: Sunbeam EM6910
Grinder: Mazzer Mini-E
Roaster: Many

Posted Sun Nov 21, 2004, 3:00pm Subject: Re: Adjusting vibe pump pressure on HX machines

Sean, it's available here: http://www.wega.it/wega/pdf/mininova.pdf. It's for the 'old' Mininova though, not the one with the full stainless steel sides. The insides are a little different I think.

strugs
Senior Member

Posted Sun Nov 21, 2004, 3:49pm Subject: Re: Adjusting vibe pump pressure on HX machines

here is the pic (Click for larger image)

- Sean

syd
Senior Member

Joined: 30 Jun 2004
Posts: 436
Location: Melbourne
Expertise: I like coffee

Espresso: Sunbeam EM6910
Grinder: Mazzer Mini-E
Roaster: Many

Posted Sun Nov 21, 2004, 4:21pm Subject: Re: Adjusting vibe pump pressure on HX machines

Well, that's very interesting. I think the valve on top of the machine you've labeled as the Brew Pressure Valve is called the 'Safety Valve' in the parts doc. When I adjusted this, it didn't affect the pump pressure to the basket. I've been adjusting what you've labeled the '2nd Pressure Valve' next to the pump. This valve changes the pump pressure to the basket.

strugs
Senior Member

Posted Sun Nov 21, 2004, 5:12pm Subject: Re: Adjusting vibe pump pressure on HX machines

Well, both OPV's are in line. My theory is that adjusting either of them influences the other one. Are you making adjustments to the OPV's while the pump is running?

- Sean

syd
Senior Member

Joined: 30 Jun 2004
Posts: 436
Location: Melbourne
Expertise: I like coffee

Espresso: Sunbeam EM6910
Grinder: Mazzer Mini-E
Roaster: Many

Posted Sun Nov 21, 2004, 6:10pm Subject: Re: Adjusting vibe pump pressure on HX machines

Here's what I've done. The machine as shipped to me had both valves screwed completely in. When I loosened the 'brew pressure valve' I couldn't get a stable pressure. It would sit at 9 and then gradually rise again. So instead of adjusting that valve I started to adjust the '2nd OPV' valve. Adjusting this valve would allow me to get a stable 9 using a basket gauge. However, since your posting and discussions with Doug (CG: MiniNova), I checked with Doug as to what his settings were, and his '2nd OPV' was about 3/4 open. I've now set up mine to the same and now I can adjust the 'brew pressure valve' so that I get a stable 9 using the basket gauge. Thanks for all your info.

strugs
Senior Member

Posted Sun Dec 26, 2004, 1:53am Subject: Re: Adjusting vibe pump pressure on HX machines

I thought I should update the WWDP crowd about more crazy "Double OPV" theories. I am off work until Wednesday, so I decided to use the down time over the holidays to tweak my espresso machine. I removed the case again today and had a good look at the plumbing. My latest theory is that the top OPV is indeed a safety valve. I think its primary purpose is to prevent excess pressue from flowing back to the pump. It bypasses the excess pressure by rerouting water to the main water line before the pump. I now believe that the bottom OPV (labeled "2nd pressure valve" in the pic I posted above) is the brew pressure control valve. As I mentioned earlier, both OPV's are in-line, so one OPV's setting can influence the other. Since they are in-line the pressure in the brew line cannot exceed the lowest setting of the two OPV's. For example, if the 1st OPV is set at 10 bar, but the 2nd is set for 15 bar, the pressure in the line will not exceed 10 bar because the 1st OPV is rerouting excess pressure to the water inlet line before the pump. If the 1st OPV is set at 15 bar, and the second is set at 10 bar, the line will be limited to 10 bar because excess pressure is routed from the 2nd OPV to the drip tray. I will be setting up my portafilter pressure guage tomorrow to see if this theory can be proven.

- Sean

strugs
Senior Member

Posted Tue Dec 28, 2004, 1:57am Subject: Re: Adjusting vibe pump pressure on HX machines

My experiments over the past two days confirmed that both OPV's affect brew pressure. For those of you unfamiliar with WEGA plumbing, it looks like this: pump OPV1 with excess pressure routed back to pump inlet copper water line OPV2 with excess pressure routed to drip tray copper water line leading to HX brew system I adjusted both OPV's so that they were closed (no pressure bleedoff). PF guage read 13 bar. Then I adjusted OPV1 while watching the PF pressure guage . At the OPV's limit, the guage did not fall below 10 bar. Then I closed OPV1 and adjusted OPV2 - same result - the brew pressure would not fall below 10 bar. It was only with a combination of opening both OPV's that I could reduce pressure to the coveted 9 bar range. With both OPV's wide open, I could actually get pressure down to 7 bar. This might explain why there are two OPV's on the WEGA machines. This type of OPV (which from pics I have seen of other machines' internals seems to be quite different from the OPV's used by most other manufacturers) must be limited in how much they can reduce pressure. Two of these OPV's are necessary to reduce system pressure to appropriate levels.

- Sean

Gerry
Senior Member

Joined: 12 Dec 2004
Posts: 15
Location: Massachusetts
Expertise: I like coffee

Espresso: Isomac Tea
Grinder: Mazzer Mini

Posted Thu Dec 30, 2004, 4:39pm Subject: Re: Adjusting vibe pump pressure on HX machines

Interesting technical details. I would be interested to know how all these pressure adjustments affected your shot flavor, and what pressure WEGA owners settled on. Gerry

strugs
Senior Member

Posted Sat Jan 1, 2005, 3:20pm Subject: Re: Adjusting vibe pump pressure on HX machines

I conducted more WEGA brew pressure experiments today. Since these experiments have hijacked the original post, I have started a new thread geared towards double OPV WEGA machines. "WEGA Lyra / Mininova Brew Pressure Adjustments"

- Sean

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