Post By Dimal
Vibration vs rotary pumps
Hereís one for the brains trust.
What are the thoughts on vibration vs rotary?
My thoughts (may be wrong) are:
Vibration - louder, canít be plumbed but better for extraction due to gentle pressure ramping up on the coffee puck.
Rotary - quieter, can be plumbed, harder on the coffee puck so more chance of chaneling.
What do others think? My main interest here is thoughts on the extraction quality, channeling, etc, etc
Vibe pumps are certainly louder, in particular when they are filling up the steam boiler or at the start of an extraction. They become quiet as they build pressure.
Whether a rotary pump makes for a more fragile puck that is sensitive to channeling I am not sure. The pressure that a rotary pump builds as soon as it is turned on is not necessarily the same as the pressure on the puck. Typically there is a restrictor in the flow path that makes for a more gentle pressure increase on the puck. Most machines with a rotary pump can be plumbed-in, however. This allows for the coffee to be soaked at water mains pressure before the pump is engaged.
Finally, it is possible to plumb in a machine with a vibe pump, but it requires a flow restrictor and solenoid valve in the water supply plus mods to tubing and wiring.
The pressure ramp can be controlled to an extent by ensuring you have an optimum sized Gicleur fitted into the Brew Circuit/Group, depending on the Thermosyphon design if applicable. The smaller the Gicleur jet size for an equivalent pressure, the slower will be the pressure build up above the coffee puck.
I think there are some models of espresso machines using a Vibe Pump that can be plumbed in. I think Bezzera has/had at least one model so there's no real reason why that can't be considered. Anyway, if both systems are designed and set up properly, neither is better/worse than the other when it comes to coffee quality in the cup. As you say though, Rotary Pumps are lovely and quiet...
Also, a quick search shows at least 3 other threads with the same title and many more with similar.
Originally Posted by Grillsy
Thanks for the replies brains trust. Thatís good reading and good learning