I bought a used Astoria Argenta Jun less than a year ago and have been running it off bottled spring water because the city water here is over chlorinated and who knows what else. As I continue to study all things espresso I have come across various machines similar to mine that require pressurized incoming water. Is that the case with all rotary pumps? The previous owner was using it the same way but I am wondering if my machine requires water pressure? If so, is there a method of pressurizing bottled water?

Most rotary pumps (and your user manual for your machine ) calls for water inlet pressure from 1 to 5 bars. You could solve by putting water supply above machine or use a flojet as others have done here on HB --if wanting to stay with bottled water. Or plumb in and put a regulator on it.

I have been running a rotary pump from an un-pressurized bottle for several years without a problem. There are several machines with reservoirs AND rotary pumps.

Unless your machine uses line pressure for preinfusion (as is the case for the plumbed-in La Marzocco GS/3 MP), no external pressure is required. From the FAQ see Do most plumb-in machines require external pressure?

HB wrote:Also see the thread Flojet and rotary pump questions. The Procon pump is spec'd at a six foot vertical lift, 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 before buying because the manufacturer may call out positive pressure, as was the case for the Elektra A3.


Ball-type check valve assures water flows only one direction

Generally speaking, the pumps in rotary pump espresso machines do not need positive pressure, so it's really a matter of whether the machine uses line pressure for preinfusion (i.e., either the brew path can be opened manually, or the group solenoid opens for a few seconds before engaging the pump). Also see Can a rotary pump suck up from a bucket?

With the Expobar 2 group (pump is a fluid-o-tech PA101) in the garage, I've been experimenting with this recently and found that although the rotary pump pulls fine from a static bottle, the brew pressure tops out at around 4.5 bar. Plumbing it in brings the pressures up to ~9 bar (adjusting at the pump). This echoes Stefano's comments on this subject on other threads Do most plumb-in machines require external pressure?

Shots pull 'alright' and I wonder if some folks who used unpressurized bottles have actually tested brew pressure. What other factors might effect the pumps ability to produce adequate brew pressure, boiler capacity perhaps? I don't know. I'd have thought most of the rotary pumps (fluid-o-tech, procon) are pretty similar spec.

I have a 1gpm Delavan on-demand coming for the static bottle, which I figure is the simplest water supply setup for a low volume machine sitting in the garage.

What other factors might effect the pumps ability to produce adequate brew pressure,

Excessive clearance between the vanes and the housing will diminish capacity.

I have a 1gpm Delavan on-demand coming for the static bottle, which I figure is the simplest water supply setup for a low volume machine sitting in the garage.

Hook that up to a 2 gallon accumulator and feed the Expobar via a pressure regulated supply.

Shots pull 'alright' and I wonder if some folks who used unpressurized bottles have actually tested brew pressure. What other factors might effect the pumps ability to produce adequate brew pressure, boiler capacity perhaps? I don't know. I'd have thought most of the rotary pumps (fluid-o-tech, procon) are pretty similar spec.

Ayup. It's easy to get the standard 9 bar (10 bar static). I've never had a problem with a bottle fed rotary pump, as long as the bottle's within a metre. Line pressure is NOT necessary.

Alan

fluke wrote:What other factors might effect the pumps ability to produce adequate brew pressure, boiler capacity perhaps?

Somethings wrong with your pump?

Good info here, thanks. I had to replace my rotary pump two months after purchasing the machine. As mentioned the PO had used it in the same fashion, pulling from a spring water bottle. I am now wondering if this "no pressure" method could of caused the pumps failure. I can plumb the machine in without much trouble as I have a capped 1/2" water mine local to it, I just don't know whether or not I can filter the water enough to be satisfactory given the chlorine levels and other additives.

1rider wrote:I am now wondering if this "no pressure" method could of caused the pumps failure.

Procon specs don't require positive pressure, so it's a safe bet the manufacturer believes it doesn't lead to breakdowns. On a related note, in this video, Bill Crossland explains how they work:
It's actually a simple mechanism and easy to rebuild in the event there is a problem.

1rider wrote:...I just don't know whether or not I can filter the water enough to be satisfactory given the chlorine levels and other additives.

If you add an accumulator to account for slow filters, you can always go with a reverse osmosis followed by a mineral cartridge. Search the forums, there are plenty of discussions of water filtering options.