Erratic Brew Pressure on Vibiemme Domobar Super

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Erratic Brew Pressure on Vibiemme Domobar Super

Postby ddabah » Wed Apr 16, 2014 9:58 am

Hi,
My Domobar used to brew at a near constant 12 Bars of pressure throughout the brew cycle. A couple of days ago the brew started to get extremely weak with the gauge jumping between 8 and 11 a few times during the cycle, with the sound and coffee flow to match.
Right before this happened I replaced the in-tank water softener so I thought it might have something to do with it. I tried brewing one time without it but still no change.
Any ideas?

Thanks,
Daniel.
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RE: Erratic Brew Pressure on Vibiemme Domobar Super

Postby KOLU » Wed Apr 16, 2014 10:41 am

Hi,
your pump is dying.
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RE: Erratic Brew Pressure on Vibiemme Domobar Super

Postby ddabah » Wed Apr 16, 2014 11:52 am

Thanks for the reply.
That's a bummer if so. The service place is closed until next week.
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Postby GreenBean » Wed Apr 16, 2014 12:03 pm

Hi Daniel, welcome to TMC :D

I agree with KOLU that the pump is a likely cause of your problem. Before sending your machine for service it may be worth checking that there are no restrictions in the water line from the tank to the pump as this could also cause the problems. Also, are you sure your machine does not need a descale? If in doubt remove the top nut from the E61 group head and inspect the mushroom, gicleur ( flow restrictor) and its associated filter screen. For information on this see the Overhauling the E61 group section of the excellent http://www.espressomyespresso.com/ site maintained by TMC member frcn.
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Postby ddabah » Wed Apr 16, 2014 12:29 pm

Thanks for the welcome and the advice.
Maybe I constricted the water flow somehow when I replaced the water softener.
I'll try the inspection you suggested.
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Postby Sarion » Sat Apr 19, 2014 11:19 am

I think I once had the same experience, and there was air trapped somewhere...

12 bar sounds a bit high to me, by the way. I`ve set mine to around 8,5 and I think 9 is normally recommended. Your coffee may taste better at a lower setting.
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Postby CakeBoy » Fri Apr 25, 2014 7:52 pm

Hi Daniel, if the worse case scenario comes to fruition and it does turn out to be the pump, you might feel comfortable swapping it out yourself if you don't mind a bit of basic plumbing. Plenty on here would advise as required. Obviously with the proviso to leave well alone if you are not comfortable and you do so at your own risk.
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Postby zix » Mon Apr 28, 2014 8:01 am

Any luck with the Domobar, Daniel? To me it sounds like air trapped somewhere. Haven't had a look inside the Super, but did look a lot inside the Domobar basic model some years past. The plastic hoses can easily get bent or trap air. If so, keep pumping water through until you hear a change in the pump sound - if you have a tank machine it must be a vibration pump, they can take a bit of punishment.
I also second CakeBoy's suggestion about lowering the pressure. Going down to 8.5-9 bars was better. 12 is just some general setting they apply from the factory, you can change it by adjusting the return flow valve (some call it OPV, over pressure valve, but since you have the Super model there might be a possibility for misunderstanding here - this is not about the safety valve on the boiler!).
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Postby ddabah » Sat May 03, 2014 7:19 am

Thanks for your help everyone. At first the technician also though it was the pump but after testing with a blind flush it turned out to be fine. The erratic pressure was apparently the result of improper grind/tamping etc..
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Postby GreenBean » Sun May 04, 2014 9:08 am

Thank you for letting us know the outcome, Daniel.
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Postby zix » Mon May 05, 2014 9:14 pm

Yep, thanks.
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