Hi,

I've been reading about pre-infusion and the benefits of it, and the fact that the E61 group does it automatically. I have a 1979 Elektra that I have restored and it has a similar thermocycling grouphead to the E61, but does NOT have the lever control as part of the grouphead like a true E61. Brewing is activated by a DPST (double-pole single throw) switch (in my case a timer switch) that does 2 things: it engages the 3way grouphead solenoid valve to open the path of the HX water to go to the grouphead via the gigleur, and simultaneously turns on the rotary vane pump to supply 9 bar pressure to the HX water path.

My question is this:
Does the design of the Elektra grouphead do an automatic pre-infusion by design? I don't think so, as I have to do a purge to clear super-heated water out of the boiler if a shot hasn't been recently drawn, but I am open to being corrected.

I read an article that confused me a bit because it mentioned the Italian espresso machine engineers talking about using superheated water to do the pre-infusion -- the literal translation is "crispy" water -- that would indicate the the usual method of doing a purge first to get rid of the superheated water is actually opposite of what is intended by the Italian engineers.... The article also said the pre-infusion is best done with lower pressure to gently wet the puck. Hmmmm. What do you folks think or know of this? Here's a link to the article that I read:
http://www.espressoresource.com/index.p ... Itemid=110

I have some thoughts about how to do a fairly simple modification to allow for a line-pressure pre-infusion on this machine. What do you "experts" think? I look forward to your thoughts.
1. Install a separate momentary push-button switch that will only activate the 3way group solenoid valve, thus opening the path of the hx water to the puck at line pressure without the pump running as long as that button is pressed. This would be simple to do -- I would call it a "pre-infusion" button.

The reason this would work is the way my Elektra (and I suspect most other plumbed-in pump-driven HX machines) are designed is that the solenoid controlled valve that determines whether the pump water is going to the boiler or to the HX is, by default, set to leave the input open to the HX, thus leaving the HX open to line pressure when the the solenoid is not activated and the pump is off. This works because the bypass valve in the rotary vane pump in most of these machines uses a "hollow" bypass valve that allows line pressure through. (Note, if a "solid" bypass valve is present, then the line pressure can't get through -- an easy mod to do if needed -- just swap out the bypass valve -- they are usually interchangeable). This probably won't work for a pour-over machine as there isn't line pressure present.
2. to perform a shot with pre-infusion I would do a purge with the regular control using the pump to to cool down the HX, grind my shot's beans and tamp which would allow the temperature to equalize in the HX while I am doing this, then put the portafilter on, press the new "pre-infusion" button until I get a drip or two out of the portafilter, wait a few seconds (now many?) and then pull the shot under pressure using the regular brew switch.

Soooo, what do y'all think about all this?

I look forward to lively discussion and feedback.

Philip

phreich wrote:I have some thoughts about how to do a fairly simple modification to allow for a line-pressure pre-infusion on this machine. What do you "experts" think? I look forward to your thoughts.1. Install a separate momentary push-button switch that will only activate the 3way group solenoid valve, thus opening the path of the hx water to the puck at line pressure without the pump running as long as that button is pressed. This would be simple to do -- I would call it a "pre-infusion" button.

I've had a similar P/I button installed on my non-e61 rotary HX for a year or so now. The P/I button I installed is not momentary, by design, because you have to press the brew button while the P/I button is ON to keep the 3-way valve from re-opening on you and ruining your shot.

I have also modded my setup to do on-the-fly adjustable line pressure, so I can P/I @ 2bar or 4bar or whatever. I did this by adding a vibe pump to the input line just before an accumulator tank.

My verdict? If you're into tinkering, go for it. I taste a marked difference depending on how much I P/I. The amount of P/I is now one of my parameters for dialing in a new coffee. Again, P/I is one more parameter, you can ruin a shot by using too much of it or improve a shot by finding just the right number.

If modding/tinkering isn't something you want to deal with on ongoing bases, I suggest you lookup a thread somewhere here about adding a timer to the brew button circuit that will activate the 3-way before the bump for a given number of seconds.

coffee.me wrote:I've had a similar P/I button installed on my non-e61 rotary HX for a year or so now. The P/I button I installed is not momentary, by design, because you have to press the brew button while the P/I button is ON to keep the 3-way valve from re-opening on you and ruining your shot.

Thanks for the first response! Interesting.... So, if I understand what you are saying is that if I let the 3way valve close, and purge the line pressure off of the pre-infused puck, and then start the 9bar pressurized brew cycle that will reopen the 3way valve, but this time to 9bar brew pressure supplied by the rotary pump, the shot will be ruined? Why is that? Is it because for a moment air will get in there when the pressure is released and some of the water on top of the puck drains out the 3way valve that has opened up, relieving the line pressure?

What I am hearing is that once the puck gets wet with preinfusion, you want the 3way valve to stay open to the hx and then when the pump comes on at 9bar, water is forced through the puck in a more continuous fashion than if you allowed the 3way to open to its default state (to where it purges the pressure from the puck).

BTW, how long do you PI, and how long do you delay afterwords before activating the brew cycle?

I look forward to your response, and explanation.

Also, I am interested in hearing what anyone has to say about the comment in the cited article that mentions the pre-infusion being done with the "crispy" water.

Philip

I added an adjustable delay on make relay to the rotary pump on my old Faema. Easy install. You set your timing interval on the relay, hit the brew switch. The solenoid opens (or rather closes) and the line pressure preinfuses the puck. Then the pump kicks on. Simple mod. You would still need to flush the heat exchanger before the shot just like you do now. I though about doing the same mod on my A3 but I dont have any issues with the pressure ramp/extraction on it. So I never did. That old two group I had was very picky and benefited from the preinfusion. The Elektra, never had any issues so I left it as is. Pulls better shots than my old Faema ever did.

phreich wrote: Soooo, what do y'all think about all this?

I think I'll be following along this thread and trying to implement this once I get my Elektra working! If I go ahead with something like this, I think I'll start with a pair of buttons as suggested - one that controls the 3-way position and another that controls the pump. Along those lines, I wonder if the machine controller is smart enough to prioritize brewing over autofill to prevent a pressure drop during a shot (I doubt it, as this is only a one group machine unlikely to need such a "smart" function unless filling a cup of hot water while brewing).

OP-- To be honest, I was also a little confused by the first responder, but it is late here and I didn't reread to be sure. No offense to the first responder at all, I am sure he/she makes a solid point and the reason I didn't understand it is because I have never considered the issue they are suggesting this may cause with the different wiring styles of divergent/different types of machines. (btw, first responder, I love the vibe pump idea)

But just to support your idea, I did exactly what you are considering. [Actually, I have a semi-auto machine that is computer controlled so I actually added in a momentary normally closed switch inline with the pump power. That way, auto fill works, etc. But when I want to line pressure preinfuse, I just press the pump-off momentary button, then press the normal brew button. When my preinfusion is complete, I just let up on the momentary pump off button, and the pump kicks in, increasing the pressure from line pressure to 8.9 bars.] This method that you propose of preinfusion... it works like a charm, the pucks are in perfect condition, no channeling (as long as your technique is good), etc. Your setup would be even easier, and I would HIGHLY recommend doing exactly what you described. If you are really adventurous, you could make it a timer switch that way your preinfusion is always the exact same length. I think another poster in here mentioned that already, and there are more than a few on the board who have done that I think.

Go for it, I noticed a positive increase in espresso quality very quickly... plus you can do some fun experimenting with slayer like brew pressure cycles and super fine grind.

If you need any further info, don't hesitate to post or PM me.

Karl

Though, just about the timer switch issue... I am not convinced that preinfusion time is necessarily a constant. I think it is a good practice, from my experience, to preinfuse to a certain point of development on the bottom of the basket, and not simply rely on time. So, just playing devil's advocate with myself in order to help you see more sides of the decision you are making.

Karl

PS: I am open to being wrong and I know ideally development and time would be directly related, but despite my dosing, leveling and tamping skill (not a pro, but quite solid and repeatable), it can be up to a second or second and a half off from one shot to the next at the exact same temp.

I think pre-infusion is overrated. What matters is reducing the pressure throughout the shot which traditional pump machines cannot offer without complicated modifications...the only thing I can do is drop the pressure a bit by running the second grouphead...and that helps smooth out the shot but only a bit, kind of like a corrective measure on a shot that I didn't grind fine enough.

You'd be much better off spending time dialing in the grind and figuring out the best shot time for the coffee you are using.

Pre-infusion I've only found helps lever machines.

Preinfusion helps on my Krups.

Someday I'll get a decent machine but for now I can make the best espresso available to me on, yes, a Krups. But preinfusion is necessary to solidify the puck (I guess) so that 15 bar pump doesn't just blast the shot thru it.

Run the steam until it's as hot as it gets, switch the control to the extraction position for no more than 2-3 seconds, then back to steam for maybe 2-4 seconds til it's starting to steam again (it's cooled to water and the thermoblock has to be heated back up, but can't spend any longer than this), then quickly back to extract the shot.

I also removed the plastic "crema disk" at the bottom of the PF so I guess it's now a semi-pressurized PF.

Quality is not bad. Sorry for the digression about my pitiful machine but I had to comment on preinfusion, an idea I got by lurking on HB. I do lust for a decent machine of course ...

Hi,

Thanks for all the input!

After gaining more experience with my restored 1979 Elektra, I did some PM-ing to a few fellow Elektra owners about some comments they have made on other pre-infusion threads and have determined the following about the Elektra group design:
The Elektra group is designed in such a way that the water path through the bell is vertical (instead of coming in at an angle like on the E61), and also has the heavy large extra brass diffuser above the final diffuser screen in the group. The combination of the 0.9mm gigleur (group orifice), the extra diffusion and the longer vertical water path causes a 3-4 second delay in the building of the 9bar pressure above the puck, which basically causes an automatic low-pressure pre-infusion to occur whenever a shot is pulled. The engineers at Elektra really figured this out well back in the 60's or 70's when they came up with the current design of the Elektra group!

Due to this, I have decided not to add a pre-infusion button to my machine as it is really not needed.

However, for other machines, pre-infusion may well still be necessary and may offer a real improvement in taste. Of course, if you have a true E61 group, then the middle position on the lever allows for line-pressure pre-infusion and no extra control buttons are necessary.

Thanks, everyone, for your thoughts on this,

Philip