20. Testing Coffee Sensor's AirBuster® on a La Pavoni Europiccola

[@yutaosong9701]

Thanks John, this video is very helpful for me to make my decision.

[@JohnMichaelHauck]

In the video, I remove the "hat" of the air buster so you can see how it works. You can hear the air escaping the group head when I lift the lever. Then, once all the air removed, the air buster valve closes with a ceremonial "spurt". The pin is up when the valve is closed. At the end of the extraction the valve remains closed (pin up) until I remove the portafilter. Then the pin drops and the valve is open again, ready for the next shot. Genius. There is no sponginess in the pull whatsoever. You cannot tell in this test, but the Europiccola boiler just came up to pressure so the group head is a bit too cold. This situation would normally create a very spongy pull (I'll post my theory of this in a different post some day). Because there is no air trapped, you can expect the portafilter to contain some residual water when you remove it. This may bother some people who hail the dry puck of a La Pavoni. I usually don't drink espresso without warming up the group head more than I did for this demonstration. The taste is a bit more sour. The neat thing is I have more control over taste with the air buster - allowing me to pull shots with a cooler group head. This is fun! After pulling three shots, the reservoir is no where near full. Taking the hat off and letting it air dry overnight is all you need to do to manage the water.

[@anylookup]

I was getting a lot of sponginess before installing the Airbuster (will test it today) but during installation discovered one of the piston seals wasn’t installed properly during sleeve upgrade (didn’t use the tool to insert the piston!) and this was damaged probably leaking. If you’re still getting sponginess check your piston seals as well and do use the tool designed to install the piston because otherwise you might have the same problem as me and wasted seals.

[@caffeebenzina1347]

I Tested it on my and my pin goes after the shot down (after 4 seconds around). Should it not be like that or why you still have enough pressure to keep the pin up?

[@JohnMichaelHauck]

@@caffeebenzina1347 This is all dependent on the ground coffee. If it is very coarsely ground, old beans, or not very much coffee, or not tamped very hard then it will not offer much resistance to the pressurized water and air, so the pin will drop sooner.

[@pierre-albertcharbit9677]

Hi, thanks a lot for this demo, is it necessary to buy the "Coffee Sensor full piston pressure kit" with this mod ?

[@JohnMichaelHauck]

Yes you need to have the full piston pressure kit (PPK) with the air buster. The air buster removes air that is trapped just under the piston (above the coffee grounds). It does through a small vertical hole that that runs through the piston and the piston rod. The PPK includes a modified piston, piston rod, and a new lever. So why do we need a new lever too? The original piston rod has a horizontal through-hole for a pin that is connected to the lever. This horizontal through hole would intersect the vertical hole needed for the PPK (pressure gauge) and air buster (air passage). The horizontal hole in the piston rod is replaced with two shallow holes on each side that do not go deep enough to intersect the vertical hole. The new lever is needed because it can accommodate two threaded pins that enter the two horizontal holes. Ok ok, I need to make a video of how the air buster works inside. In the mean time, my other video of how the PPK works should help.

[@pierre-albertcharbit9677]

@@JohnMichaelHauck Thanks John, and congrats for your work. I think Coffee Sensor should sell the complete kit for this mod. The gauge in the PPK kit becomes useless. Spongy pulls can be avoided by locking the portafilter just after introducing some water/steam in the group, and by doing this my ratio is often 1:2

[@JohnMichaelHauck]

@@pierre-albertcharbit9677, When I installed the air buster, I used the gauge from the PPK and connected it to the "T" connector supplied by the air buster. The PPK gauge is now mounted sideways, so it is a bit strange to get used to. In other words, I can still watch my extraction pressure using the PPK and get the benefits of the air buster at the same time. I do think that Coffee Sensor could offer a PPK+AirBuster package for people who do not already have a PPK. As for avoiding spongy pulls, I agree that there are techniques to reduce the amount of trapped air without using the air buster. Getting the group head plenty hot (by a combination of letting the machine heat up a while and flushing hot water though the group head before attaching the portafilter) will reduce the sponginess of the pull. A hot group head, however, may cause the espresso to taste more bitter as the hot water extracts a bit too many of the off flavors. I am, however, concerned that I do not completely understand your points, and I may have addressed something you did not mention.

[@pierre-albertcharbit9677]

​@@JohnMichaelHauck Thanks, you understood my clumsy words accurately ! Indeed I do not have the PPK kit, and I find it strange to have to buy 2 expensive kits, with parts of a kit that will not be used (PPK gauge). So I'm waiting for a AirBuster package before pulling the trigger ! Ok for the benefits of AirBuster when cooler group head is needed. That's a good point because I like very roasted coffees, which need lower temp. Tchusss

[@GeelongVic7140]

Any comments about the ultimate taste of the espresso delivered into the cup? Taste is what ultimately matters.

[@JohnMichaelHauck]

I really don't want to make public claims with respect to taste... for many reasons: I've never been formally trained in tasting coffee. I have very little experience tasting espresso from a vast variety of machines. It is subjective, and I really cannot make any defensible statement. I suspect if I do, arguments from better qualified people would ensue. Anyway, I can say that is allows larger shot volumes if you are brewing at cooler temperatures. If you think those would help your experience, then maybe this is for you. To be clear, the air buster does not cause the brew temperature to be cooler. To do that, you have many options.

[@rueljuachon4374]

Just like asking a guy presenting a ceramic coating protection to his car. "Will it make the car faster? Only the speed matters. Study what the product is intended for.

[@BrucePappas]

Cool! Why the wet puck?

[@JohnMichaelHauck]

Bruce, with the piston fully down (after the shot), there is still a bit of a gap between the top of the coffee grounds and the bottom of the piston. Without the air buster, this would be air. If the air buster does its job, there is no residual trapped air, so now this is water. So when you remove the portafilter, you are also letting that trapped water out.

[@BrucePappas]

@@JohnMichaelHauck - got it.

[@thedownhilla]

@@JohnMichaelHauck Would you imagine a piston throw adjustment (ie reducing piston to showerscreen space) would assist in reducing puck "water-logging" after the shot is complete?

[@JohnMichaelHauck]

@@thedownhilla I agree with you 100% that reducing the piston-to-shower screen space would certainly help. Also, reducing the gap between the top of the coffee grounds and the bottom of the shower screen would also help. The first could be done by using the lock nut and adjusting the depth - which I really should do. The second could be done with more coffee grounds or a smaller filter basket.

[@ronaldorodan8762]

Hey John, could you elaborate on depth adjustment? The puck part, maybe a certain amount of water is needed for pre to total infusion as to avoid the partially dry puck syndrome.

[@scriptkeeper8243]

Where'd ya get that cool shovel handle mod?

[@JohnMichaelHauck]

coffee-sensor.com/product/la-pavoni-lever-limited-edition-levine-special-fork-and-lever-arm-from-stainless/

[@Wyrdrock]

Awesome! What effect on the espresso do you notice with the airbuster? Do you get more volume in your shot? Does it function differently on your first vs third shot for example? How about if you pass water through the grouphead before pulling a shot?

[@JohnMichaelHauck]

So many questions! The extraction in the video was between the 44ml and 60ml lines on the cup... so I'm estimating 50ml. This is not including the crema on top. I think I usually would get 40ml on the unit before the air buster. The biggest difference is that I no longer heat up the group head as much. I used to turn on the machine 20 minutes before brewing and dispense a quick burst of hot water just before the shot to eliminate the spongy pull. However, the espresso was never bitter then so in terms of taste, I think there is not much of a difference. The operation from shot to shot is no different than before. Quickly dispensing a burst of hot water also seems to work just like before. So the biggest take-away is that you can brew a bit cooler, never have a spongy pull, shot volumes are up, not even a hint of residual pressure when removing the portafilter, and a puck that is wetter - which seems like a small negative.

[@Wyrdrock]

@@JohnMichaelHauck Thanks! I've been looking for info in this thing. I'm running a bong isolator on my gen 2 so I have to run hot water through my group head to get it up to temp. Compared with just flushing the grouphead before a shot, how does spongyness compare?

[@JohnMichaelHauck]

@@Wyrdrock Well, the puck was always dry without the air buster and is always wet with it. So it is a big difference. I suspect the air buster makes an even bigger difference with the bong isolator, since the isolator really can cause spongy pulls.

[@randalbladel2817]

Wait: wouldn’t a cooler group head have less air (steam) than a hot one? I thought the reason there was air (steam) in the group head was because the water from the boiler, which is hotter than 100 C because it is under 1 bar of pressure, boils in the lower pressure group head and creates the air space with steam. This should be worse with a hot group, which would support the boiling even more than a cooler group. What am I missing here?

[@JohnMichaelHauck]

Randal, I will try to clarify, but please follow up because there is a good chance I am missing your point. You twice wrote, “…air (steam) …”. I am guessing that you might be indicating that air and steam are much the same thing. I know many people think of steam as just hot-moist air. My understanding is that steam is a gas made up of 100% water molecules (H2O), and air is a gas made up of mostly Nitrogen (N) and about 20% oxygen (O). They really are different. For example, when steam cools off, it condenses and becomes water. Air on the other hand does not become a liquid (unless things get spectacularly cold). Consider the area above the ground coffee and below the piston on La Pavoni. When we attach the portafilter and raise the piston, the area is full of air (the air came in the bottom through the ground coffee). Now when we completely raise the piston, hot water from the boiler enters the area. This hot water flash vaporizes into steam. The more steam that comes in, the more air is driven out through the ground coffee. Then, the steam cools and turns to water - leaving the area 100% water with no trapped air. If there was not enough steam to drive off all the air, then the remaining air will be trapped in the area. This gives you a spongy pull. The amount of steam generated is a function of the temperature of the water as it enters the area. The hotter the water, the more steam is generated. Am I helping at all? Maybe check out kzbin.info/www/bejne/rWPTgIWlrNFqqJYsi=Tvv5BR11RWjKwPUL

[@ModeX9]

does this have an effect on pre-infusion?

[@JohnMichaelHauck]

I am not sure. The reasons is should not have an effect: The AB does not change the water pressure on the puck while the lever is left up - which is boiler pressure. There is water saturating the puck with and without the AB. The reasons is could have an effect: As the water rushes in the group head, the pressure inside the group head is lower, because some air is escaping from the AB. Then when the AB suddenly closes, there is a quick spike in pressure up to the boiler pressure. So I conclude... is is possible. From personal experience, I think I am so enamored by the lack of sponginess (or in other words, a solid feel) that I really have not noticed anything different in taste. I think my taste is biased simply by the experience of pulling a shot with a La Pavoni. Pulling shots on our church machine (Laspaziale Vivaldi II) just does not taste as good. Could I tell while blindfolded? Probably not.

[@barista-home]

Здравствуйте, где взять переходник для манометра?

[@JohnMichaelHauck]

coffee-sensor.com/

[@yuvalhazan2798]

Hey, quick question, what kind of lever do you use? Would love to have something like that on my pro.

[@JohnMichaelHauck]

I personally designed the handle and it was manufactured by coffee-sensor.com/. There is a discussion about it here: facebook.com/groups/lapavonienthusiastsgroup

[@JohnMichaelHauck]

A limited edition of the lever is now being sold here: coffee-sensor.com/product/la-pavoni-lever-limited-edition-levine-special-fork-and-lever-arm-from-stainless