Getting a Handle on Inlet Water Pressure "Flutter"

[NewEnglandCliff]

My La Spaziale S1 is plumbed from a water bottle via a Flojet. While brewing, the Flojet cycles rapidly on and off causing an inlet pressure fluctuation often termed "flutter". Fluttering-like interruptions in the espresso stream frequently occur as a result. It's been written that smoothing the inlet flow can result in a "clarity" or "transparency" in the cup whereby individual flavors are more clearly defined, and that a means to that end could include employing a number of devices. These include a static tank, accumulator, filtration cartridge, water hammer arrester, check valve, pressure regulator, or a combination of these. Whether I'll perceive "clarity" could be arguable, but I've no doubt (from a common sense standpoint) that a consistently smooth inlet pressure will benefit my equipment and my espresso.

Swimming through all the data but finding no clear consensus, it seems an accumulator is becoming the popular recommendation. But can someone tell me if using an accumulator will result in a positive line pressure even while the espresso machine is off? Many S1 owners experience slowly dripping expansion valves with line pressure and I want to avoid that. Are there any S1 owners who've tried this arrangement, ie. Flojet w/accumulator?

Malachi implied that a filtration cartridge muted the fluctuations enough where it produced the desired clarity. I don't need filtration, but since this setup could avoid the (drip causing) line pressure this seems like a viable choice. Are there any more recommendations from anyone, or new data?

[cappadoc]

Cliff,
I have an S1 with the FloJet and accumulator setup you described, as I suspect you already know from my posts on the S1 forum.
I am trying to think of a way to test for positive line pressure without just disconnecting the water line and seeing what the resulting mess is like . If anyone can think of a simple way to test this, I'd be happy to check it out. I assume there is positive pressure equal to the accumulator tank pressure, factory set at 20psi.
I've not had problems with the leaking expansion valve, but I would imagine that if you set the pressure in the accumulator fairly low (say 10 psi), any leak would be fairly small. I THINK this is true because the max leak should be the total accumulator volume (mine is 24 oz) less the resistance caused by gravity in the line and the expansion valve itself.
If your main concern is leaking during extended trips away from home, consider turning off both the S1 and the FloJet when you leave. That should be possible if you wire the S1 and pump into the same circuit and put a switch in the line. That probably sounds simpler in theory than it is in practice, but I guess that depends on how forgiving your SO is . I mean, really, what's one more wiring project in the pursuit of perfect espresso!
Anywho, let's keep the ideas flowing for a solution to your dilemma.


Jeff

[NewEnglandCliff]

Thanks Jeff,

Leaking while away is a concern but I usually disconnect the power then anyway. Leaking while I'm not away is more the issue, as people are reporting a volume of over 8oz/day. At that rate I'd have to regularly empty the drip tray, which I never have to do now. If you're not getting any leaking, that could be the answer I'm looking for since Chris at Chris Coffee says all of his S1's, plus all of La Spaziales machines in Italy routinely drip.

I would have thought setting the pressure of the accumulator low would be an issue, as it was previously held that rotary pump machines required a fair amount of line pressure. However some evidence lately suggests that's not the case, depending on the type of rotary pump, the relative location of the water supply, whether the machine uses preinfusion, and perhaps other elements of machine design. Indeed, some of the devices I first mentioned are to be used without a Flojet at all. I don't understand the use of a static tank in addition to the 5 gallon jug. Seems like the jug IS a static tank. Still, from what I've been reading, the accumulator with a Flojet sounds like the best solution. Have you noticed any improvements in your shots?

[Abe Carmeli]

I had the same problem on my hookup. Though, I do not use a static tank. Here is what solved the problem: I installed a 90 psi booster pump with an accumulator tank, and an adjustable pressure regulator on the other end (inlet to the espresso machine pump). The booster pump recycles at 70 psi, and the pressure regulator was set to 55 psi. Having 15-20 psi buffer zone between line pressure and the inlet pressure smoothed out any fluctuation during the recycle of the booster pump. It is rock steady.

[cappadoc]

Cliff,
Sorry, but I can't comment on shot quality differences with and without the accumulator. I installed it about a week after getting the S1, and I have improved my technique since then and I now use Black Cat almost exclusively, so my shots are all perfect now .


Jeff

[NewEnglandCliff]

I had the same problem on my hookup. Though, I do not use a static tank. Here is what solved the problem: I installed a 90 psi booster pump with an accumulator tank, and an adjustable pressure regulator on the other end (inlet to the espresso machine pump). The booster pump recycles at 70 psi, and the pressure regulator was set to 55 psi. Having 15-20 psi buffer zone between line pressure and the inlet pressure smoothed out any fluctuation during the recycle of the booster pump. It is rock steady.

You're plumbed in to city water, right? You have a pump, and then an accumulator, and then a regulator before the machine? Why wouldn't just an accumulator work, aren't they adjustable for a consistent output?

[NewEnglandCliff]

Recently discovered this at the Flojet website regarding their pump:

For installation and use with commercial coffee and tea brewing equipment:

Many commercial coffee and tea brewing machines can be connected to a water supply line. Ensure that you have a 1/4" I.D. connection fitting at the water inlet that can accept the supplied 1/4" O.D. tubing. These brewing machines have a factory installed device that restricts incoming water to a safe pressure that won't damage the brewing machine. This device is usually referred to as an inlet pressure regulator or flow restrictor, and limits incoming water pressure to approx. 90-100 psi. If you intend to use the Flojet BW system with one of these brewing machines, you should remove the brewing machine's inlet restrictor device. Consult the brewing machine manufacturer for details. Failure to remove the brewing machine's restrictor may cause the Flojet BW series pump to cycle itself off and on repeatedly, leading to premature motor failure of the Flojet BW unit. This type of failure is not covered under warranty.

I don't recall this being addressed anywhere. Could it be that removing any existing "inlet pressure regulator" that may be installed in our machines would resolve the constant cycling? Has anyone removed it on their machine?

[Abe Carmeli]

You're plumbed in to city water, right? You have a pump, and then an accumulator, and then a regulator before the machine? Why wouldn't just an accumulator work, aren't they adjustable for a consistent output?

An accumulator alone may work if you have high enough line pressure. My city water line pressure is way too low - 1.5 bars. I live on a platform at the top of the main mast of a clipper ship. Water get a little tired by the time they get up to me. Don't get me started on the problems I have with seagulls.

[NewEnglandCliff]

Coool! I'll bet you have quite a view. That is low pressure.

Regarding my last post of the Flojet, that information isn't in my manual which is otherwise identical to the website's tech data sheet, so this is likely recently added information. I don't see how a regulator set over 90psi would affect the Flojet since it's output is 40psi. I'll have to pass this by Chris Coffee.

UPDATE

Queried Chris Nachtrieb at Chris Coffee and this was his response:

The flow restrictor in an espresso machine is called a gicleur valve and without it the espresso machine would not work. You would get a shot of espresso in 4 seconds.

Chris

So much for that easy solution.

[barry]

UPDATE

Queried Chris Nachtrieb at Chris Coffee and this was his response:

The flow restrictor in an espresso machine is called a gicleur valve and without it the espresso machine would not work. You would get a shot of espresso in 4 seconds.

Chris

So much for that easy solution.

fwiw, chris is incorrect wrt the impact of a gicleur.

[NewEnglandCliff]

I broke down and installed a Shurflo accumulator. For the legions who need to know, the S1 doesn't leak. I've set the accumulator to 20psi (factory setting) as well as 30 psi and absolutely no leaks. For the first time I've found what the Flojet sounds like to run smoothly. The higher the accumulator is set, the less often the pump has to run (but it'll run a little longer each time). It also runs quieter. The brew pressure of the S1 does have to be adjusted each time after readjusting the accumulator pressure. When I first installed the accum. the brew pressure had fallen to 6 bar, from 9. Once adjusted it stays rock steady.

I can't say I've noticed any difference in my shots or any "clarity". They're still great.