Hi All,

Just recently got a Rocket Appartamento, I am seeing the extraction flow always pulsating (fast, slow, fast, slow, etc) during the middle of an extraction. I really can't figure out why and I don't think I am channeling as I distribute using an OCD knockoff and tamp pretty evenly and leveled.

Example 1: See about 25 secs in Example 2: See about 25 secs in Could it have something to do with the pressure from the vibration pump? I noticed the water flow never gets super stable like the rotary pumps even when the majority of the water dance stops after 25 seconds of cooling flush.

Water dance example using a single spout:

It is likely that the OPV that should hold the maximum brew pressure is sticky. When liquid starts to flow, the OPV should partially close to hold the pressure. If it doesn't, the pressure declines until the OPV is kicked closed and pressure builds again. You can check by removing the cover from the reservoir and watch the return flow to the tank. That should behave similarly erratic, but inverse to the liquid flow out of the grouphead. It would explain the change in hum of the pump as well. Higher pressure = lower noise and vice versa. Remedy could be to remove the OPV internals (spring, valve piston), clean them in citric acid, rinse and put back in.

I'm not expert, but looks and sounds fine to me, only thing noticing is pump speed changing when heater turns off.

Got a call back from the retailer (Seattle Coffee Gear), their technician also thinks the minor flow fluctuations during the extraction is normal behavior for a vibration pump. Any 2nd/3rd opinions?

Yes, this has been my experience with vibe pumps. Though there is no fluctuation reading on my manometer during the shot (stays @ 9.5 bar rock steady), just the occasional flow "flutter".

I agree that the flow looks normal in your video. I had a Rocket Cellini PID machine with a vibratory pump, and it looked like that too.

I like vibratory pumps because they ramp up to full pressure over several seconds rather than starting at full force like rotary pumps.

Rocky

Seeing this video just reassured me what a magnificent machine the Rocket is, sure wish it was available when I bought that piece of crap Mara............... enjoy my friend it looks amazing you made a really good decision.

Shot looks completely normal to me. You get this with spouted portafilters towards the end of the shot, nothing wrong with it. I'm sure if you used a bottomless the flow would be steady. Would suggest not running the shot 50 seconds though, at about the 25 second mark you're probably done with extraction.... the flow fluctuation you see, especially at say the 45 second mark, is your machine struggling to extract more from the coffee. If it taste good to you, then don't listen to me and change nothing

Thanks everyone for the confirmation.

Update:
I also got a naked portafilter and the flow is really smooth and beautiful: