Thread: Expobar Office Control brewing times: diagnosis help needed, please

Originally Posted by rsnidjik

I've just bought an eight-year-old Expobar Office Control and am learning to use it. My previous machine was a PID'd Silvia, so most of my learning curve has to do with getting used to an HX machine.

With the Expobar, I've noticed that the machine can take a very long time to put out water through the group head if it's been powered on but sitting idle for a while. I'm trying to figure out if this is normal behavior or not.

Here's some data:

At initial warm-up in the morning, if I pull a shot right after the brew light first goes out, water comes out of the group head almost immediately when I hit the brew switch. Subsequent shots take much longer, though.

The chart below shows the wait time for water to emerge at various times following the previous shot.

5 minutes after previous shot: 11 secs.
10 minutes after previous shot: 30 secs.
20 minutes after previous shot: 42 secs.
30 minutes after previous shot: 43 secs.
60 minutes after previous shot: 48 secs.

I ran this sequence a second time and got very similar timings.

Once the machine is initially warmed up, steam and hot water emerge from their respective outlets without a wait regardless of the time elapsed since previous shot.

Is this behavior normal for an HX machine?

If this isn't normal, does anyone know how I can diagnose the problem? Thank you very much.

Now this is interesting. I’d want to check the bypass valve (return to tank) after the pump. As the machine and HX circuit heat up the water expands and forces through the OPV (over pressure relief valve) or bypass.

When you try to extract a shot you may be losing water that returns to the tank as opposed to routing directly to the group shower.

Originally Posted by sprezzatura

Now this is interesting. I’d want to check the bypass valve (return to tank) after the pump. As the machine and HX circuit heat up the water expands and forces through the OPV (over pressure relief valve) or bypass.

When you try to extract a shot you may be losing water that returns to the tank as opposed to routing directly to the group shower.

Thank you very much, sprezzatura. I'm waiting for the machine to cool down so I can go exploring. Is this the problem someone else with the same machine and similar symptoms described here?

#3:Post

I'll poke around and report back.

Originally Posted by rsnidjik

Thank you very much, sprezzatura. I'm waiting for the machine to cool down so I can go exploring. Is this the problem someone else with the same machine and similar symptoms described here?

#3:Post

I'll poke around and report back.

They’re on the same track. No priming valve but, yes, OPV valve issue.

I have a new Expobar Office Control and it doesn’t behave like that. Water can be dispensed shot after shot consistently, assuming the grinds etc are the same regardless how long the machine has been idle.
Not well versed enough around HX machines to tell what could be wrong here. :/

My opv is before the hx, so it is in cold water. You can see how much water is bypassing by removing the bypass line and monitor the water flowing out that pipe. There should be none, unless you are pulling a shot.
I had recent intermittent flow issues with my pump. It turned out to be that 'priming valve' in the snout of the pump (I'd call it a one way valve, as it allows the pump to take it's next stroke of water and pump it past the valve). I could hear the pump vibing, but little water was coming out. The water was just sloshing back and forth with the pumps piston (the pump was a little quieter though)

My hot water is supplied from the hx circuit, so is pump supplied. I understand many machines supply hot water from the bottom of the boiler, this maybe why your hot/steam supplies are working fine.