I recently moved to NW Indiana outside Chicago. Last year I purchased a Brewtus I from J. Klein (on the northside). It has been working well, but now I need to replace the OPV. I am not a super mechanically inclined person but would love to learn how to do it and learn more about my machine in the process. (I'm also looking to get more connected to the espresso culture in the Chicagoland area.)

J. suggested that I post and see if there is anyone who would be willing to open the machine up with me and help show me how to do this repair. You may also be able to help me see if there is anything else going on with the machine that I am unaware of.

Thanks,
m

An obvious question - what makes you think you need to replace that OPV?

You might also try posing this request here: http://groups.google.com/group/brewtus

Are you confusing the OPV (over pressure valve) with the vacuum breaker? Those go bad after a few years but OPV's rarely go bad.

I came to the OPV diagnosis this way:
(1) After over a year of pulling espresso and getting very consistent at it, I suddenly started having every shot come out too quickly. No matter how much finer I adjusted the grind, it would start coming out at around 5 seconds (instead of eight), and the coffee would pour out with no tiger striping, with gushers, etc., and it was blonding at around 15 seconds. Also tasted horrible. At first I thought the problem was my grinder. Baratza actually sent me a refurbished grinder (Vario) after discussing it over the phone. But nothing changed with the new grinder.
(2) I called WLL technical support and discussed the problem. They said it was most likely the OPV either needed to be adjusted or replaced. They also sent me some diagrams.
(3) I opened the machine to adjust the OPV for less pressure. I turned the nylon adjustment screw less than 1/4 turn counterclockwise and tried another shot to see if there would be any noticeable difference. But then after my next shot I saw a trickle of water coming from the machine. I looked more closely and saw water collecting on top of the nylon screw and then trickling down from there.

This seemed to confirm to me that the OPV is having a problem, like WLL thought.

Does that make sense? Does it still sound like the OPV is not the problem?

Thanks.

They also sent me some diagrams.

I would be interested in exactly what diagrams they sent you but, yes, it does certainly "sound" as though the o-ring for the nylon adjusting screw has "seen a better day".



What sort of maintenance have you done to the machine, i.e. detergent backflushing, water backflushing? There are two hoses going into your reservoir - one is the pump suction hose (probably has a water softener cartridge attached) and the other is a combined hose from the OPV and the pump priming/deaeration valve. When you simulate a shot with the blind filter, this combo hose should have flow of ABOUT 1.50 ml/second or 3 ounces per minute (IIRC). You can take a measurement using a pyrex cupper.

Seems to me as though your problem is beyond the OPV although any leak there obviously needs to be fixed first.

The diagram was very simple. Just an exploded view of the OPV valve itself and some basic instructions for where to find it and how to adjust it.

I forgot to say that I did test the output from the return hose, at WLL's suggestion. But they did not say to measure it. Only to see if it was coming out evenly (not sputtering or in bursts) and without trailing off once the pressure built. It passed both those tests, in my judgment. I tested with a blind filter. Once the backflush was under way and the pump pressure built up as normal for a backflush (after a few seconds), water flowed evenly out of the return hose, starting slowly and increasing to something steady. So I couldn't observe anything particularly problematic there.

As far as maintenance, I backflush with water after I'm done pulling shots each session. I usually backflush with detergent every week. Of course, sometimes it is more than that (10 days or even 2 weeks).

What other problems beyond the OPV are you concerned may be present?

Mininger wrote:I came to the OPV diagnosis this way:
(1) After over a year of pulling espresso and getting very consistent at it, I suddenly started having every shot come out too quickly. No matter how much finer I adjusted the grind, it would start coming out at around 5 seconds (instead of eight), and the coffee would pour out with no tiger striping, with gushers, etc., and it was blonding at around 15 seconds. Also tasted horrible. At first I thought the problem was my grinder. Baratza actually sent me a refurbished grinder (Vario) after discussing it over the phone. But nothing changed with the new grinder.

If you pump were running at 18 bar, rather than 9, it would run as fast or slower, not faster. There is no linear or observable relation between flow and pump pressure once you get over about 5 bar. This problem is either caused by very old coffee, a Sumatra or an improperly adjusted grinder.

The Vario frequently requires a zero adjust as described in the various threads here. It is easy to check this. Every espresso grinder's finest setting should produce a turkish grind, a powder with no perceptible granularity when you rub it between your fingers. The proper espresso grind coarser than this; it is granular, but just, finer than table salt, or finely ground sugar, more like stone ground flour.

What other problems beyond the OPV are you concerned may be present?

The preinfusion valve in the grouphead not opening. See here for a pictorial - E61 Group Espresso Machine: Detailed Interior Schematics

another_jim wrote:This problem is either caused by very old coffee, a Sumatra or an improperly adjusted grinder.

This is what I assumed too. But so far as I can tell it has not turned out that way.

As for the grinder, I've always adjusted my Vario every month or so, just to be sure it is where it should be (where the burrs start to make contact when the macro arm is at zero and the micro arm is halfway up--as described in the manual, and Baratza confirmed this with me when we were on the phone). Once these problems started, I checked it over several times (including both the larger allen screw, under the rubber cover, and the smaller allen screw that is not) to be sure. There was no problem there.

As for coffee, all of it was 5-8 days from being roasted, which is what I try to do as a rule. It happened with quite a few different beans, but none was Sumatra. (One roast did have some Sulawesi in it, but it was about 20%. And other roasts had none.) Plus, the pull wasn't even close to normal. In the past, if I have pulled old coffee, it is faster, but you can just adjust finer and it will slow down considerably. For me, it is gushing even when I have the grind level almost to where the burrs are touching.

So as far as I can tell, then, the grinder and the beans are not the issue. Unless there is something further I should try to test those variables out.

erics wrote:The preinfusion valve in the grouphead not opening.

Are there characteristic signs if this is the issue? Or is there a way I can test to confirm?

Also, do you think I should be assuming that the OPV does also need replacing (if there is water coming out the top, as I described before)?