I am trying to test a 3 phase coffee machine and don't have a pressure water supply where I have 3 phase, so will a rotary pump suck up water from a bucket? I know this isn't good for the pump, but it's for a short time ...

I have a rancilio s27, and it sucks water fine. Not sure about long term, but I can't see how it would hurt. The only issue I'd have is to make sure the line is primed, some pumps don't like to pump air, and water is also a cooling agent, so as long as the "bucket' is full can't see a problem.
P.S a friend of mine re-wired a lathe from 3 phase to 1 (motor,did loose reverse though), not sure what will be cheaper for you, 1 phase pump and heater, or re-wire.

Rotary pumps do not need positive pressure to work, so presumably a check valve would suffice (to prevent the water from draining out and introducing air bubbles). That said, I would double-check with the vendor beforehand because the manufacturer may call out positive pressure. For example, Eric reports that without positive pressure, the pump on the Quickmill Vetrano cavitates (link).


Ball-type check valve assures water flows only one direction

Whether your espresso machine will extract correctly is another question. For example, some rely on the line pressure for preinfusion. I've read reports of some commercial espresso machines relying on line pressure to fill the boiler too. The owner's manual or your dealer should have instructions on proper installation.

I am running my Vetrano from a bottle. I keep it right next to the machine so it doesn't draw against gravity. Chris at Chris Coffee has assured me it will work fine.

One question. How does one know if a pump is cavitating?

Trust me, if your espresso machine's pump was cavitating, you'd know. I made the mistake once of connecting the Elektra A3 to 1/4" inlet tubing. It worked OK when pulling a shot, but squealed madly during a boiler refill. Switching to 3/8" inlet tubing returned the Elektra to its usual whisper-quiet self.

sweaner wrote:One question. How does one know if a pump is cavitating?

Scott -

You would suspect a cavitation condition from the sound the pump makes and the corresponding reduction in flow during a flush. A very reliable number for Vetrano's flow during flushing is 0.28 oz/sec or 16.8 oz/minute with a pump inlet pressure of ~ 35 psi. I was running some tests on a loaner Vetrano and INITIALLY set it up to take suction from a homemade water container.

I experienced cavitation and a great reduction in flow and promptly changed the setup to get water from a nearby regulated source - problem solved. Re the Elektra operation that Dan mentioned, I have operated an Elektra and those gems are very quiet when properly installed - almost silent.

The pump in Vetrano has a suction line (internal to the machine) with an ID of 3.0 mm. whereas the threading on the pump (3/8" BSPP) has an ID of ~ 15.0 mm. This dramatic reduction puts a strain on the pump, IMO, when suction conditions are anything other than a regulated pressure source of ~ 35 psi.

It sure would be interesting to hear what your flowrate is during a flush.

Eric, I will measure my flow rate the next time I use the machine...hopefully tonight.

The techs at Chris', and Chris himself have assured me that I will not harm the machine. I am hopeful to have it plumbed in soon.

I would put faith in what CC has to say re Vetrano taking suction from a bottle. Perhaps I had a machine with a "tired" pump. However, my GUT feel is that this type of operation is questionable. When you do plumb it in, I would certainly recommend the pressure regulator and water filter/softener apparatus that CC sells in the 3/8" size.

While rebuilding my Elektra T1 I ran it from a bucket with a large plastic hose. The bucket was slightly below the level of the pump so that a leak wouldn't flood things. It managed to suck the water up the hose and it filled the boiler. I pulled about 6 shots one day, test for leaks, (fixed them) then tested some more.

I also ran it from an extension cord to the kitchen so I could plug into a GFI circuit just in case...

Now it's fed from a filtered, water softened, pressure regulated supply and it's wonderful.

Mark

I would like to make something clear here. I have never condoned the running of a rotary pump from a bucket. Will it work? Yes, it will work. Is it good for the pump? Absolutely not. In fact, I will not warranty a pump that has been used in this manner. If you run the pump dry for only a short period of time, you run a very good chance of destroying the pump. I am really not interested in hearing any rebuttals either. You can do what you want, but if your pump burns up, it IS NOT COVERED UNDER WARRANTY...

Chris, my machine is not covered under your warranty. However, I was assured by your company that I could not hurt the pump/machine by running it this way. I discussed this with the techs when they serviced the machine, which I bought used. Obviously, if the bottle runs dry I will be putting a new pump in. However, I need to really know if I am actually hurting the pump by running it without any line pressure.

Eric, by the way, the flow rate was 8 oz in 29 seconds.

Every time you run the tank dry, even for a short time, or have to prime the pump because it loses prime, you are doing damage to it. If you insist on running it that way, at least put a good check valve in line so as not to lose prime. Bottom line, a pump run this way versus the way it was designed to run is much more likely to wear out sooner than it should.

Thanks Chris. Does anyone have a suggestion on a check valve? Is it something I can get from the Home Depot plumbing supply section, and will it simply attach to the end of the hose?

Scott -

I believe the item you need is called a "foot valve". You will likely need to adapt it to the 3/8" pipe threads that are at the end of the Vetrano hose. A Google search for "foot valve" will be revealing.

Keep in mind that you want to minimize the additional "strain" you impose on the pump. A pic of your current setup would be helpful.

Yes you can run a rotary from a jug, but as Chris points out, you can burn up the pump if you run the water tank dry. Having said that, I know someone that ran a 3 group LM from a water tank, if you keep you water bucket above the pumps horizontal plane you will have some slight positive pressure but again, run it empty and you may fry your pump. The OP is from New Zealand, I cannot suggest a location for the check valve out there, but here in the US you can get them from McMaster, Grainger, maybe even Lowes hardware. Any plumbing supply store should have them; just ask for a one way valve or a check valve.