Rocket not pumping on plumbed line

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

#1: Post by ctar »

Greetings - I purchased a Rocket Mozzafiato Chronometro earlier this year. The machine is plumbed in with a pressure regulator and the cheap filter/softener setup available at Chris' Coffee. The problem is this machine stops pumping in the afternoon after the machine has been hot for a few hours. The pump runs noisily and no water (either on refille of tank or pulling shot). If I switch to tank mode, the machine works fine. Sometimes switching to tank and back to plumbed gets things going again, but I think the problem is subtle and intermittent enough that it resolves after switching the pump on and off a few times. Sometimes this doesn't work, I need to turn off the machine and let it cool down for a while.

When this problem happens I see no water demand from the machine, as determined by looking at the pressure gauge which shows good pressure and the needle never moves (see videos).

I have been back and forth with the guys at and they say they believe there is no problem with the machine because in tank mode it works fine and that a solenoid is either 100% broken or 100% good. They suspected a problem with my water source, but I don't believe that's the problem. Appreciate any input on this. I will also say that sometimes even in tank mode it sounds like when first switching on the pump the water demand is not great, but stabilizes after a second or two - this is basically because there is often a buzzing noise (not electrical, mechanical) when first pulling up the lever, but after a second or two things sound good and pumping is fine. I'm really hoping not to ship this 60 pound beast out to get repaired. I am handy but also really just want this taken care of properly as it's effectively a brand new machine and this problem has been there pretty much since I have had it plumbed in.

The first video shows the machine struggling and then coming back to life and running Ok. This is what happens after turning off the not working machine for 30 minutes and then turning it back on. The second set of videos is to show there seems to be no demand from the machine when it's not working, but needle bouncing around happily when it is working. Thanks for any insights!



#2: Post by JRising »

Take a look at the coils for the pair of solenoid valves in the back corner. The ones that choose which water source to open. a 240 V coil may open at 120V if its nice and cool. (These two that share a T-fitting)

If you run the machine with the back off, you can check whether or not the valve coils are charged by touching a screwdriver to the end of the valve and feeling the magnetic attraction. BE VERY CAREFUL WITH A SCREWDRIVER IN A LIVE MACHINE.

Also check the switch behind the reservoir, The current for the valve does run through that switch. If the contacts are bad, or the switch isn't very good it will introduce some resistance. Also check the connection 6 inches below the switch, if the connection isn't secure it may lose contact.

That's all I can think of so far. My money is on 240V coils on the valves.

User avatar
Randy G.

#3: Post by Randy G. »

What have you done to verify that when this happens that there is sufficient water flow to the machine? That is, have you eliminated the filters and regulator from the equation? If you have a spare length of tubing, go directly from the water source to the espresso machine and see if that eliminates the problem.
Espresso! My Espresso! -
LMWDP #644


#4: Post by ctar »

Jrising you mean you think they accidentally installed a 240V valve on my US/120V machine?

Randy, I can skip the filter setup but as mentioned I don't see any movement on the regulator dial or PEX when the problem is happening, I would think you would see some movement there indicating some water movement? Also when I turn the pressure regulator UP it goes up which I think means there is good pressure otherwise the dial would go down? I guess it's possible the pressure is all on the "left-hand side" of the filter setup but the pretty consistent relationship with the machine temp tells me this is unlikely


#5: Post by ctar »

Ok, I am liking more this idea that the solenoid/valve is the wrong voltage. It explains why I hear a mechanical buzzing when things aren't working - the solenoid is getting current but not enough to open. If that's the issue, shouldn't I just be able to look at the model or designation of the solenoid and confirm whether it's 115V or 230V? Also, just to confirm my understanding only one of these two solenoids opens when pulling the lever, and the tap/tank switch simply chooses which one(green or orange in my drawing)? Thanks again!


#6: Post by JRising »

Just look at the coil, the black cube. The voltage is printed on the coil.
I think you already know the red one in the pic is the one for the Plumbed in inlet, but look at them both.


#7: Post by ctar »

All three solenoids are 115v/60hz...


#8: Post by JRising »

Swap the coils between Reservoir and Plumbed (And of course move the wires over, back to the proper valves). See if that makes a difference.
I may be hyperfocusing on that plumb-in solenoid valve, but your description sure points here.

Next time the issue occurs, flick the switch behind the reservoir over to reservoir, then back to Plumbed while the machine is running. If this fixes it, then we can focus on what's wrong with the switch instead of looking in the wrong corner.