Last week I received my new espresso machine. A Vibiemme Domobar regular, a e61 single boiler. (sort of a zaffiro / alexia).

Yesterday I switched beans and when I dialed the grinder a bit finer, it choked the machine for about 10 seconds. Then the portafilter slipped out and I heard a big bang. Coffee sprayed all over the kitchen and the group gasket and rubber ring stuck half way out.

So after a 20 minute clean up i decided it was more of a tea night.

The next day I put the gasket and rubber ring back in its place. When I put the machine back on, the pressure started to go up to 10 bar everytime the boiler cycles.
The only way to get it back to normal is to turn the steam valve open. (lots of hissing, sputtering, steam and water)

Did I wrecked my 10 day old machine?

koffieboon wrote:When I put the machine back on, the pressure started to go up to 10 bar everytime the boiler cycles.

That's normal. As the water heats in a closed system, it expands, driving up the pressure. Once the brew arm is lifted, the pump determines the brew pressure. The over-pressure valve prevents the system from being exposed to excessive pressure by opening around 10 bar, although you can adjust it lower since this same valve determines the brew pressure. Search for 'OPV' in the FAQs and Favorites for more information.

Pfew, Glad i didn't wreck the machine. I will try to bring the pressure down half a bar. Thanks for the answer and the FAQ list. I've enjoyed reading them. It's really nice to have this community. Especially since there aren't many people where I'm from, that are into this espresso thing.

koffieboon wrote:I will try to bring the pressure down half a bar.

Note the pressure reading while you are pulling a shot. Frequently, the "dynamic pressure" with water flowing to the puck will be 0.5 bar or more less than the "static" pressure. With some luck, you might find your OPV is close enough already.

Jim

Thanks for the input Jim!

When I 'm pulling a shot, (2 ounce / 60 ml in 30 seconds from the moment pushing the lever upwards) the pressure slowly hits 10 bar, so I'm guessing this means that the puck is getting 9 bar.

This weekend I will try to read up on the 'dynamic pressure' in the FAQ. So I will leave the machine at rest for now.

koffieboon wrote:When I 'm pulling a shot, (2 ounce / 60 ml in 30 seconds from the moment pushing the lever upwards) the pressure slowly hits 10 bar, so I'm guessing this means that the puck is getting 9 bar.

Hi, jorrit -

I think I misled you (unintentionally, of course). What I meant to communicate was that the indicated pressure with a blind filter in place would probably read 0.5 bar higher than the pressure when pulling a shot. This is because the OPV is shunting 100% of the flow in one case, and a smaller fraction in the other.

I did not mean to say that the pressure at the puck during a shot would be lower than the pressure on the gauge. I would think that the pressure at the puck is very close to 10 bar based on your last post (assuming of course that the machine's gauge is accurate).

Jim

On board gauges tend to run 0.5 to 1.0 bar higher than actual brew pressure when you are using a blind basket (backflush basket). The exception being rotary pumps, they tend to be much closer to the actual brew pressure.

Today I finally got time to open up the vibiemme. I've read up on OPV's but I would like some feedback before I really start to make some changes.


Should I turn this screw right (clockwise) to bring the pressure down? (While the machine is running with a blindfilter in place)

Or should the machine be off while changing the OPV and should I check later?

JimG wrote:assuming of course that the machine's gauge is accurate

For now, I'm assuming it is. (The machine is a few weeks old)

koffieboon wrote:Should I turn this screw right (clockwise) to bring the pressure down? (While the machine is running with a blindfilter in place)

The screw compresses a spring; clockwise = more resistance = less water escapes = higher pressure. Counter-clockwise = less resistance = more water escapes = lower pressure.

Or should the machine be off while changing the OPV and should I check later?

It's wise to unplug the machine before sticking a screwdriver in it.

Thanks for the quick reply, I've changed the setting to 9 bar on the blindfilter, let's see if I can taste the difference.