I own a Bunn ES-1A. Having upgraded from a vibe pump machine, I always thought that the lack of all-out buzzing was a great thing. I recently, however, stood next to a Nuova Simonelli Mac Digit as a few shots were pulled. It was FAR quieter than my Bunn - nearly silent. Now focused on the sound a pro machine makes, I visited a brand new (hence nearly empty & quiet) coffee shop in my area. When the barista switched on the pump, I heard nothing. I also have a friend who I visited this evening, and his machine (also HX / rotary pump) makes about the same intensity of a whirring sound as the pump on my Bunn.

My question is this; Should a properly functioning rotary pump be silent, near silent, or make a whirring sound? My pump is soon to be rebuilt anyway, but I am very curious to know if a noisy rotary pump is necessarily a pump in need of a repair/rebuild, or is it's OK for one to be noisy.

Thanks!

David

dmankin wrote:My question is this; Should a properly functioning rotary pump be silent, near silent, or make a whirring sound?

Vibratory pumps get a bad rap because... they vibrate. If you run one free from an espresso machine's casing, it makes less noise than an electric razor. Alas vibratory pumps do indeed vibrate, producing a tinny reverberation of interior components. I'm not making this up, I "outboarded" mine and the noise level is about the same as an inboard rotary pump:



Rotary pumps by their nature produce very little vibration. If they have an ample water supply to avoid cavitating, they operate nearly silently. If they're mounted externally as is the case in the majority of cafes, you will hear nothing unless you open the cabinet and listen carefully. Most manufacturers of inboard rotary pump espresso machines mount them on squishy rubber footings, arresting the little vibration the pump produces.

I assume the whirring sound you hear is not from the pump itself, but sound produced by sympathetic vibration. Mounts that are made of too hard a rubber, not enough rubber, components touching each other, etc. can result in odd buzzing that is very difficult to locate. As a case in point, the original La Spaziale S1 rotary pump mounts were replaced by slightly softer rubber in the final production model. I retrofitted them in during the final weeks of testing and was astounded by the noise level reduction. So the answer to your question "Should a properly functioning rotary pump be silent, near silent, or make a whirring sound?" is regrettably "it depends."

HB wrote:I assume the whirring sound you hear is not from the pump itself, but sound produced by sympathetic vibration.

I think there's a lot of difference in the amount of noise produced by the various electric motors that drive the rotary pumps.

My old Francis!Francis X5 was very quiet in comparision to my Anita. (This is even after a fairly major attempt at quieting my entire system down by putting Dynamat through out the inside). Of course the Anita is WAY better at espresso. I turned on an Elektra that I'm rebuilding and wow, the rotary is WAY quieter than the Anita and the X5.

Mark

I have a vetrano, and it's usually fairly quiet. However, every now and then, I pull a shot and there is this very quiet, low-frequency vibration that sounds like the pipes in the system. It's fairly quiet, but very aggravating--It kinda sounds like something is damaged or in the process of getting there.

I understand that this is somewhat common on QM machines, which is kind of disappointing. I have been meaning to ask if there is an easy fix for this, or even a mildly painful one.

dmankin wrote:(...) stood next to a Nuova Simonelli Mac Digit as a few shots were pulled. (...) visited a brand new (hence nearly empty & quiet) coffee shop in my area. When the barista switched on the pump, I heard nothing.

Hello David, do you know if the other machines had external pumps? If they were under the counter it would be a lot quieter.

Henry

Henry,

Only the machine in the coffee shop had an external pump - The Mac Digit, my friend's Rancilio & my Bunn all have an internal rotary pump.

David

Cool. Wonder what it is then? Some of my favorite extraction videos are from Dan's "week with the GS3" thread, in most of them the solenoid clicks are louder then the motor...

I used a CMA commercial machine for a summer and the motor (or pump?) was fairly loud.

Henry

My question is this; Should a properly functioning rotary pump be silent, near silent, or make a whirring sound?

David -

Of your three choices, the most correct answer would be near silent. A whirring sound is, to me, indicative of a bearing(s) (motor or pump) getting tired. That said, it may very well be easy to mechanically disconnect the pump from the motor without loosening any water line connections. Hey - this could be a practice session for your rebuild If you shoot some pics with a camera, I'm fairly certain you will pick up the audio also. Do all of this with the machine at room temp.

The inlet and outlet connections on the pump should both be something other than hard piping but make sure they are not putting any stress on the pump housing. The noise resulting from cavitation (poor inlet conditions for the pump) could also loosely translate into a "whirring" noise. What sort of pressure do you maintain at the inlet to the machine during operation? Or better yet, what pressure does Bunn want you to have and do they have specific installation instructions for this machine?

Some other checks not necessarily connected with "whirring" would be the condition of the mounts for the motor and the tightness of the mount fasteners.

edit - added pump mfg install notes:

http://www.fluid-o-tech.com/files/Instr ... 0-1000.pdf

http://www.proconpumps.com/PDFs/Install ... ctions.pdf

erics wrote:...That said, it may very well be easy to mechanically disconnect the pump from the motor without loosening any water line connections. Hey - this could be a practice session for your rebuild If you shoot some pics with a camera, I'm fairly certain you will pick up the audio also. Do all of this with the machine at room temp...

Eric,

Thanks for your comments. It's sort of a long story, but in trying to stop my pump from leaking around the pressure adjustment screw, I overtightened the locking bolt and.. um... broke the thing. I STRONGLY believe that the pump was nearing its end, since it was putting out 5 bars when recently checked with a reliable gauge, and when I increased the shot pressure to acceptable levels, the leak became more substantial.

I am going to try to pull the pump out tomorrow in order to have it rebuilt, so I'll be sure to engage the the motor w/o pump to see how quiet or noisy it runs. The pump has to go out anyway, so noisy or not, I have a busted pressure adjustment screw & it will need to be replaced/rebuilt.

BTW, I'm just down the road from you, so if you ever find yourself on the Virginia side, there's a shot of espresso or three for you - assuming I get the Bunn ES-1A back up and running!

Here's a video of my machine BEFORE I killed the pump! My digital camera doesn't do sound very well, but you can get an idea of the type of sound she made.

«missing video»

Thanks again, Eric

David