Profitec Pro 500 brew pressure dropping

Equipment doesn't work? Troubleshooting? If you're handy, members can help.

#1: Post by nlaul1 »

Hi: recently the brew pressure on my pro 500 PID has been unexpectedly dropping but it's not consistent. Sometimes it drops from 10 bar and fluctuates between 5 and 7 bar when making coffee. This doesn't happen at all when I use the blind disk and the brew pressure it at 10 bar.

There are times when the brew pressure gauge also seems "stuck" and sits at 8 bar even after the coffee is made and the portafilter removed. Once I start flowing water through the head, it resets again.

All this doesn't happen consistently - once every 2-3 brews. Would welcome any advice people have on what may be happening.

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#2: Post by Jeff »

"Stuck" suggests that the the tube or fittings leading to the valve are clogged. Coupled with the previous problems with the vacuum breaker, my guess is that you've got a scale problem and the machine might benefit from a complete descaling. What does the mushroom look like?

nlaul1 (original poster)

#3: Post by nlaul1 (original poster) »

Haven't looked at the mushroom but I just descaled it a month back.

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#4: Post by cafeIKE »

How old is the machine?
Group ever rebuilt?

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#5: Post by JRising »

It sounds like the machine is probably okay, to me, the pressure drop when brewing is normal if the coffee "Puck" breaks apart as the oils are flushed out of it. You could dose a little more to help it retain it's resistance to flow a little longer. Be sure to be using fresh coffee or it will wash out far too quickly.

As for "Stuck", I don't think the gauge is stuck at all. I think you're trapping 8 bar of pressure in the brew circuit because the pump is still running when the brew valve (The upper one in an E61 head) closes. The gauge is working fine and reporting the actual pressure. You can move the switch behind the control lever back so that it dis-engages sooner during the lowering of the lever, this will let a little more of the water escape the brew-circuit before the brew valve closes completely. It doesn't really matter, it doesn't hurt anything to have pressure trapped in there, the expansion valve won't let it get too high.

If you put a gauge on the tire of your car and it's 32 PSI on Monday, you test it again Wednesday and it's still 32 PSI, it's not because it's "Stuck", it's because it's working.