I recently got a Flojet to use with my Izzo Alex (before now, I was running off of the internal reservoir). Setup was a breeze, and the convenience of not having to refill the tank is great. BUT, there's a problem: while pulling shots, the flojet constantly pulses between on and off (maybe every 0.5 seconds or so), oscillating between 8 and 9 bars. Sometime, after 10-20 seconds, the flojet suddenly stays on and the pressure stabilizes at ~9.5 bars. I called Chris Coffee about this, they checked it out on an Alex there and said that the same thing happens there, so I shouldn't worry about it. I can't imagine that this pulsing is doing good things for my extractions, or the consistency between shots at least, so I'd like to figure out what's going on. The Flojet manual says that it will behave like this if your machine has a pressure regulator on it, but I don't think the Alex does. Any similar experiences/solutions?
DavecUK Senior Member Joined: 21 Sep 2005 Posts: 203 Location: UK Expertise: I love coffee
Espresso: Izzo Alex Duetto (serial... Grinder: Mazzer Mini E Roaster: Toper 1kg (sold) Gene Cafe
Posted Fri May 2, 2008, 4:28pm Subject: Re: Flojet+Alex?
You have a pressure regulator...the rotary pump. Because of the pumps bypass system, it's not going to draw very much water during a shot, which will cause the flowjet to pulse. During a double shot, you are only pulling 60ml in 30 seconds, or 2ml per second, that's really not very much is it. This teaspoon of water every 3 seconds is going to cause the flowjet to start and stop.
If it was a vibe pump machine it wouldn't be so bad, because they would still be flowing some water through the OPV, but on a rotary, she is only going to draw what she puts out the other end. I expect you get far less pulsing or none at all when the boiler refills after drawing water.
Even so, I would be surprised if the pulses transfer to the brew gauge as changes in brew pressure, or do anything to the flow or your espresso, as the bypass system in the pump should cope OK with the small variations the flojet introduces?
veganjosh Senior Member Joined: 8 Apr 2005 Posts: 45 Location: Oakland, CA Expertise: I live coffee
Espresso: Izzo Alex Grinder: Compak K10WBC, Mahlkoenig... Vac Pot: Cona D Drip: Technivorm, Aeropress Roaster: Hottop B
Posted Fri May 2, 2008, 9:08pm Subject: Re: Flojet+Alex?
DavecUK Said:
Even so, I would be surprised if the pulses transfer to the brew gauge as changes in brew pressure, or do anything to the flow or your espresso, as the bypass system in the pump should cope OK with the small variations the flojet introduces?
Nope, the pulses definitely transfer through: like I said, the brew pressure gauge jumps up and down by around 1 bar of pressure multiple times per second throughout the brew!
DavecUK Senior Member Joined: 21 Sep 2005 Posts: 203 Location: UK Expertise: I love coffee
Espresso: Izzo Alex Duetto (serial... Grinder: Mazzer Mini E Roaster: Toper 1kg (sold) Gene Cafe
Posted Sat May 3, 2008, 1:37am Subject: Re: Flojet+Alex?
Pity, the flow jet pulsing must be quite rapid and violent then. I suppose if the 1 bar fluctuation is affecting your shot then you will have to do something about it.
Posted Sat May 3, 2008, 3:07am Subject: Re: Flojet+Alex?
veganjosh Said:
BUT, there's a problem: while pulling shots, the flojet constantly pulses between on and off (maybe every 0.5 seconds or so), oscillating between 8 and 9 bars.
I agree with Michell and Jon, an accumulator nicely eliminates the pulsing as the Flojet cycles on/off. It's a small container with an internal bladder that is pressurized to 20 PSI; it acts as a buffer between the Flojet and espresso machine. Even with two machines connected, the Flojet only cycles for a few seconds every couple minutes versus the beeeeeeeennnh... pause... beeeeeeeennnh... pause every few seconds during an extraction.
veganjosh Senior Member Joined: 8 Apr 2005 Posts: 45 Location: Oakland, CA Expertise: I live coffee
Espresso: Izzo Alex Grinder: Compak K10WBC, Mahlkoenig... Vac Pot: Cona D Drip: Technivorm, Aeropress Roaster: Hottop B
Posted Sat May 3, 2008, 7:37am Subject: Re: Flojet+Alex?
dan_kehn Said:
I agree with Michell and Jon, an accumulator nicely eliminates the pulsing as the Flojet cycles on/off. It's a small container with an internal bladder that is pressurized to 20 PSI; it acts as a buffer between the Flojet and espresso machine. Even with two machines connected, the Flojet only cycles for a few seconds every couple minutes versus the beeeeeeeennnh... pause... beeeeeeeennnh... pause every few seconds during an extraction.
Great, sounds like the accumulator is a good solution. Thanks guys!
I am still curious why this seems to happen just on the Alex, though. Can any Flojet users with similar machines (e.g. Vetrano) weigh in on whether a similar issue has come up? If the problem is just related to having a rotary pump, you'd think this would be a common issue...and if it's unique to the Alex, I wonder what's strange about its internals.
I live in a rented apartment with roommates that aren't so into the massive amount of coffee stuff I have. The Flojet lets me avoid using the internal reservoir and keep a 5 gallon jug neatly tucked away (and hence a few feet from the machine). My limited understanding of rotary pumps is that I could run directly from the jug if it were right next to the machine, but my jug needs to be a few feet away, and since I don't know anything about pumps I figured I'd rather throw down the cash for a Flojet rather than push the limit on how far the jug could be and risk hurting the pump.
DavecUK Senior Member Joined: 21 Sep 2005 Posts: 203 Location: UK Expertise: I love coffee
Espresso: Izzo Alex Duetto (serial... Grinder: Mazzer Mini E Roaster: Toper 1kg (sold) Gene Cafe
Posted Sat May 3, 2008, 2:35pm Subject: Re: Flojet+Alex?
Interesting...The pump used in an Alex is theoretically capable of drawing nearly 6ft, I have certainly drawn up from the full length of the hose. So the tank as low as possible from the machine would be the most challenging situation for the pump. Now if your water container is roughly on the same level as the machine (or a foot or so lower), the hose is the same length, whether the container is as far away as the hose can reach from the machine, or next to the machine. Hence the distance doesn't matter.
A flowjet seems to be unecessary for your situation and to spend further money on an accumulator would be a shame. The only thing you should be careful of is water with limescale because of the 1 way valve in the brew circuit (under the boiler) and for obvious reasons the difficulties this can cause when running from the Internal, or external tank, if the scaling gets really bad.
I fully intend running my Izzo Alex Duetto from a container when it arrives, and I would do so on my MK1 Alex if it had the capability.
The flow rates within the Alex are small Alex are in comparison to the pumps rated capacity, so you really don't need massive flow or pressure.
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