When I fired up my new Bezzera for the first time, I noticed that when it started filling itself, a steady stream of water came back to the water tank through the exhaust tube (or whatever it's really called) for maybe the first 20 seconds.

I would suspect this is water that was inside the system from a factory test. I could of course be wrong and this could have actually been the same fresh water that was going in -- getting pushed straight out for some reason.

If it's water that's been there from the factory, what's your take on this? With the overall attitude here being quite demanding on a cleaning and descaling routine, and emptying out a machine before putting it in storage, you'd think that a machine sitting in a warehouse for a year or two with water inside it would cause the same kinds of problems.

It came from a retailer in Germany but was in the factory's original sealed box. Thus testing prior to shipping is not a possibility.

It is true that my unit has been manufactured in 2011, so it has not been sitting anywhere for more than a year.

I'm just trying to get thoughts on this. No one guarantees someone else's unit has not been sitting in some big retailers (like Amazon) warehouse for a few years before being shipped. People here say that leaving water inside the system for more than 6 months already is a problem. So, if manufacturers even leave water inside the system after testing it (because I might just be wrong about the whole thing) are people here crazy with their cleaning requirements or are manufacturers messing up by not taking this into consideration?

An espresso imponderable...

pl wrote:When I fired up my new Bezzera for the first time, I noticed that when it started filling itself, a steady stream of water came back to the water tank through the exhaust tube (or whatever it's really called) for maybe the first 20 seconds. I would suspect this is water that was inside the system from a factory test.

You didn't mention the model and your profile doesn't list equipment, but let's assume it's a heat exchanger espresso machine. See the diagram below:


From How can I adjust the brew pressure of a vibe pump espresso machine?

For water to exit the over-pressure valve, the boiler fill solenoid must be closed and the exit from the grouphead sufficiently blocked (either by a blank filter basket or a coffee puck). Normally during the first start up, the steam boiler must be filled, so the fill boiler solenoid should have been open and the three way valve closed.

Based on your observation above, I would guess that the boiler fill solenoid was momentarily stuck shut, so water exited from the only available pathway, the over-pressure valve. Since the heat exchanger has a volume of only a few ounces, the pump would have filled it in quickly. Unless you heard sloshing of water in the steam boiler, it's more likely that what you observed was the heat exchanger filling and then water overflowing to the OPV.

For what it's worth, I've received a few espresso machines direct from the factory and none were filled with water. That said, it's not uncommon for vendors to bench test espresso machines before shipment; if so, they'll typically include a note explaining that the presence of some water stains is expected.

pl wrote:So, if manufacturers even leave water inside the system after testing it (because I might just be wrong about the whole thing) are people here crazy with their cleaning requirements or are manufacturers messing up by not taking this into consideration?

I really, really doubt the manufacturer left water in the system; the risk of freeze damage is too high. I recently tested a Bezzera BZ07. The original factory seal was present and the machine was bone dry. But for reference, Advice about bringing an espresso machine out of storage? offers recommendations on the subject. In short, follow the same steps as a descale to clear the boiler of any funky water.

Thanks! Very informative. I was actually hoping someone would have a diagram of the flow. So I was probably wrong about the source of the water, as the pipes would not be able to hold enough and the boiler and parts past that don't seem like they could push anything back to the tank. Or can it come back through the boiler fill solenoid and continue to the over-pressure valve?

It's the BZ10 which is based on the BZ07. So double boiler HX should be right.

Based on what you said, should I be worried if water seems to be always dripping or running through the over-pressure valve no matter if the boiler is being filled or water is being pushed directly to the group? Would that indicate something being partly blocked etc? Or is the vibration motor just quite strong compared to the valves so some always needs to escape?

pl wrote:Or can it come back through the boiler fill solenoid and continue to the over-pressure valve?

No.

pl wrote:Or is the vibration motor just quite strong compared to the valves so some always needs to escape?

I still don't get it: Why adjust the OPV? elaborates on this point. If there's no resistance to the pump's output, the OPV should not open. If the resistance is greater than the OPV's setpoint (usually around 9 to 11 bar), it should open as explained in the thread I referenced in my first post.

All that said, what really matters performance-wise is the reading on the brew gauge while pulling an extraction. It's reading is otherwise meaningless. Judging from the information you've provided, I believe there's no need for concern and you should turn your attention to making exceptional espresso.

Thanks for all the replies

The explanations seem very reasonable. I had a very different kind of machine before so I'm just trying to make sure there are no faults that are out of my control that I should take care of first. Hard to weigh your coffee if your scale is broken, so to say...

I now have a better understanding of how the flow of the machine works. Combining factors like the pressure gauge showing the desired figure to the boiler taking quite long to fill for the first time and the physical impossibilities for the water to flow back once it has reached the boiler, I'd say my suspicions were unjustified.

The machine showed some signs of hasty/trainee assembly like the front buttons not being connected properly and some rubber pipes were leaning against the boiler that I've seen in pictures to have routed differently, so I just wanted to make sure if leaving water in the system is usual (and start discussion about if it's something that should not be done) or if it was just something the person assembling it had forgot about. Turns out it was probably neither and my initial analysis was wrong.