TL;DR - I'm trying to add some pre-infusion / lower the water debit to see if improves espresso in the cup.

First, some background:

My main gear, purchased a number of years ago, is:
1) Wega Airy EPU 1-group commercial solenoid "E60.5" group. Rotary pump driven & not a lot of (apparent) pre-infusion happening
2) Mazzer major grinder.
3) Naked portafilter.
4) Roast my own beans to "medium" (225C, for what that's worth) and stick to the same/very similar blend

After a few years of being relatively happy with the above, and using a dissecting needle to WDT the grounds, I started getting increasingly annoyed by inconsistent shots, as evidenced by channeling, gushers and spurters from the naked filter, and bitterness in the cup. We drink 95% "flat whites", so the milk was covering up the laziness.

Finally stirred to wanting improve the cup quality, I've just been hitting the barista / espresso / coffee forums again after a break of several years, and realise there have been a few changes since 2007-10, when the aim seemed to be "double shot of 30-40mls of espresso in 22-25 seconds, at 9-bar". Now it's about weights and extraction ratios and total dissolved solids. Great - this suits the baker/scientist in me!

So, I've now purchased an IMS basket (16-20g, H26.5), an OCD V2 distribution tool, and have a LevTamp on the way. I'm now weighing my doses, and have found that 17g seems to fit the IMS basket really nicely. I'm going for 34-38 grams extraction weight and already the spurters and gushers have been eliminated, and the extractions are *much* more consistent and drinkable now, both with milk and straight. I'm a happy camper!

The next thing then is reading about pre-infusion and water flow / debits. I've seen it suggested that we should be aiming for 250-300mls of water per 30 seconds from the group. I've also read threads where people have added delay circuits and redesigned their group head to try to add preinfusion (e.g. My long and rambling path to preinfusion/pressure profiling).

My Wega puts out about 470mls over 30 seconds, with the pressure set at around 8.5 bar. I have an inline ball valve tap on the plumbed in water line, and shutting that right down and/or dialling the rotary pump right back, I can get the water flow down to 300mls/30 secs, although I can hear the pump cavitating a little. Pressure on the gauge is down to around 4 bar (i.e mains pressure). Extracting an espresso using this set up, it looked much more like the E61 espresso porn on youtue , and tasted fine to my uncultured palate. Extraction was only slightly slower than when the pressure was 8-9 bar and flow was 470mls/30 seconds.

So - should I be overly worried about preinfusion and water flow on this group/machine? Should I mod with a delay relay so that I get just mains pressure for ~5 seconds before the pumps kicks in? Should I try a smaller gicleur (I'm not even sure there is one in my group, but may take it apart tomorrow to check)? Should I continue with my attenuated flow rate/low pump pressures? Should I set the Wega back to "stock" i.e. full mains flow and 8-9 bar as Wega designed it?

Thanks in advance

Hey Curtis,

Looks like you have a pretty sweet setup to work with. Personally, I would highly recommend figuring out what gicleur you have in your group (likely a 0.7mm, as that is really common in the mushroom valves of E61 and E60.5 groups, but not guaranteed...) and either stepping down to a 0.5mm or just putting the switch in like I recently did here to kill the pump. Or both...

Putting in a kill switch is super easy and all you need is a switch, some wire, 3 female spade connectors and one male to have a completely reversable modification. It works great, and you're in complete control of the preinfusion. I watch the bottom of the bottomless portafilter and kick the pump on once the entire bottom is saturated with "preflow". While you're machine is certainly wired different than mine, I strongly suspect you have a relay that controls the pump and that there is a wire going from your brew switch and/or the gicar control board to that relay. Just unplug the control wire, hook your male spade connector onto that wire, plug the other end of that wire into your switch with one of the female connectors and then run another wire from the switch back to the relay with the remaining two female connectors. Voila, manual control of when your pump turns on.

Let us know what you decide and how it turns out!

- Jake

Thanks Jake.

I'll do both mods, but instead of a manual on-off switch, I'll go for an adjustable "delay on make" relay. The adjustability of it means it's more automated, and around 5-6 seconds should be perfect. Hopefully the SPST relay I've ordered will do the trick (https://www.amazon.com/gp/product/B01LY ... UTF8&psc=1). If not, there are more expensive ones which definitely should as I've seen them working from older threads (tend to be SPDT, which *shouldn't* make a difference).

I've also ordered a 0.5mm gicleur to tame the free water flow a bit. According to the wegausaparts, it's likely a 0.7mm gicleur in there (ref: https://docs.wixstatic.com/ugd/0a284f_f ... a5f3a0.pdf).

I have to say, just with restricting the water flow (to 3 bar) and pump pressure (to 6 bar with puck in place) using the outboard water line tap and adjusting the procon's OPV, the shots are turning out great. Still, where there's a will, there a mod, right?

Will report back once the above parts have arrived and are installed

Update: the cheap ICM102 didn't work out, since the settable delay is either 2 seconds or 40 seconds, and nothing in between. I had expected 0.03 mins to 10 mins to be a little more linear! Not sure if this is due to a bad individual unit (not likely, as the Amazon reviews say similar), or cheap potentiometer or bad circuit design, or all three, but stay away from this model for this purpose, 230v owners.

Still, it was easy enough to wire in line right next to the pump motor, and proves the concept can work.

So, I've ordered a Dayton 2A561 (https://m.grainger.com/mobile/product/D ... elay-2A561) which looks a little better quality, and time delay is from 1-10 seconds, so should be in the zone. One issue is that it's only 1 amp, and the pump, at 230v, 330w *may* draw a little more. Will let you know how that goes next!

You should be able to grab the input to the relay that controls the pump, which will pull very low current. That is unless it's all contained in the control board on your machine... can you post a pic?

Nice work getting it all together!

- Jake

Jake_G wrote:You should be able to grab the input to the relay that controls the pump, which will pull very low current.
- Jake

Good thought, but it's not obvious where that relay is, and the wiring is pretty tightly loomed. I also think the group solenoid allowing water flow is controlled by the same relay.

I'll have another look inside when the replacement relay arrives, but at this stage, having wired the icm102, the 2A561 is just a plug in replacement.

An update: the 2A561 and new 0.5mm gicleur arrived this morning...

I have just installed both the above parts and they're working great (from a technical standpoint).

The 2A561 make-on-delay relay is perfect for this 220-240VAC application and provides precise, adjustable 1-10 second control over when the pump kicks in, allowing readily adjustable pre-infusion times. There's no apparent issue with the stated 1A load limit (although YMMV, and the longevity remains to be determined in my machine @ 330W). Note, even though my unit only has 120VAC input stamped on it (photos below), the 2A561's specs are confirmed as 24-240VAC (https://www.grainger.com/product/DAYTON ... elay-2A561). It's very easy to install, with only a single wire to cut in-line on the pump's power feed. No mucking around with earths or negatives or multiple poles/throws.

It turns out my old gicleur was worn out as it looked a lot wider than 0.7mm - more like 1mm - hence the excessive flow rate. The new 0.5mm one may have been machined too small. Either way there was a *large* visible difference between the two. Fitting the 0.5mm gicleur resulted in far too *slow* a water flow, and I only got around 50mls in 30 seconds at full mains pressure. So I used a fine dissecting needle to open the orifice just a fraction, and now get 270-275mls in 30 seconds at full mains pressure. Perfect!

The first espresso made with everything in place came out very nicely:
VST 15g, 30g extraction over ~25 seconds, w/8 second pre-infusion @ 4 bar, followed by 8 bar w/pump = Lovely smooth, even extraction through the VST basket.

The preinfusion and reduction of water flow seems to be helping consistency and forgiveness. I will post more after some more experimenting and practice. Marked this one as [SOLVED]!

Photos of the relay installation:

Well, the 2A561 has died already, and the pump is now turning on without delay i.e the relay has failed "closed".

Given the unit I received looked somewhat used, I've ordered a brand new one. If it too fails early, it'll be time to consider a stronger bit of kit.

OK - the new (this one actually looks new) 2A561 has been in several days, and seems to be holding up. I've put a bit of insulation around it since it's only a couple of cms away from the boiler.

I've got it set to 5 seconds delay, and compared with no delay (after the original relay died), extraction is definitely more consistent and forgiving (VST 15g, OCD v.2, Levtamp @ 8 bar).

Yay!