Confessions of a PID Silvia Owner (upgrade fever)

#1: Post by **sru_tx** » July 16th, 2005, 9:04 am

Hello. I'm Steve and I'm an electrical engineer who enjoys tinkering.

{group response} HI STEVE!

I started out with a stock Silvia and Rocky. After a year of learning that good espresso is elusive, I started home roasting, first with a stock air roaster, then modded for better temp control, and finally to a 4# drum roaster. My hand basket was packed and I was on my way to coffee hell!

I've been with Silvia for nearly 5 years now. As finicky as she is, she's taught me well. I learned to surf with her. I PID'd her two years ago and now my wife enjoys her too. (I didn't even KNOW she was into that

). I even bought her nice bottomless PF for Valentine's Day. But lately I've been getting the urge do a little more.....

It started out innocent enough. My wife left town to 3 weeks on business so I figured it was time give Silvia a little more attention. I was planning on adding a boiler pre-heater using some copper tubing and the heat from the boiler to help stabilize boiler temperature. Simple enough. I hit a snag along the way. While doing some testing I realized that there was some water coming out of that mysterious second line in the reservoir. What the ?

After a lot of reading and searching archives on various forums I finally found my answer. OVP!!! I didn't even know she had an OVP. Once again, Silvia is teaching me more about espresso. The OVP changed the whole concept of preheating the boiler water. I had calculated the tubing to have enough water pre-heated to be nearly equal the volume of a shot (2-2.5 oz.); however, with the OVP bypassing water means there's a lot more water moving through the coil than expected. What to do?

At this point, I am considering putting in an adjustable expansion valve between the pump and the pre-heater coil. The valve would limit the pressure and would allow the excess of unheated water to return to the reservoir and still allow the preheater to effectively heat the water.

So here's my quandary..... for less than $50 I should be able to add a high quality valve to Silvia. I would have a pressure-limited PID'd Silvia with hopefully improved temperature stability (due to the pre heater). The only thing missing is... a rotary pump, an E61 group, and ...... Andy S, watch out! Honestly, I don't see myself going further than this with Silvia. I don't want a Frankensilvia.

I'm questioning if this last step is worth my time or should I just pass Silvia on with her PID and let her teach someone else while I move up? I'm starting to look at the Andreja Premium or the Bricoletta. I'm starting to feel like Dustin Hoffman in "The Graduate".

Any thoughts? Please help. My wife is coming home soon!!!

#2: Post by HB » July 16th, 2005, 10:06 am

HI STEVE! (yes, my kids watch "Blue's Clues" too

).

Mike Walsh loaned me his PID'd Silvia; you can read about it under Rancilio Silvia Flash Review, Reloaded. Interestingly enough, he and I are thinking that the next significant improvement for Silvia fans will come from enhancing the preinfusion / extraction capabilities. However, if you prefer blends that demand a strick slant-L profile, the preheat coil would help and your idea to relocate the OPV before it makes sense to me.

PS: Bob Yellin's review of the Andreja Premium contrasts it with his PID'd Silvia.

July 16th, 2005, 11:12 am

Thanks for the quick reply, Dan! My intro was intended to be more of a 12-step joke. I didn't even think of Blue's Clues. I'm more of a Sponge Bob guy.

I came across the Silvia flash review yesterday. I guess I answered my question before I asked it. Fifty bucks as opposed to >$1K isn't that much of an investment which may slake my upgrade thirst for a while. I think I can fit an Isomac expansion valve under the reservoir to make a clean upgrade.

Would you mind expanding on what you said?

"the next significant improvement for Silvia fans will come from enhancing the preinfusion / extraction capabilities. However, if you prefer blends that demand a strick slant-L profile"

Would bumping the pump momentarily and then setting for a moment emulate a preinfusion by wetting the grounds under low(er) pressure?

One last question which should perhaps be another question:
If I do the expansion valve I need adjust the pressure and I don't feel like buying more unitaskers such as a PF pressure gauge. Looking at Jim's runoff method, I am questioning the calculation. Specifically, the Ulka pump is showing around 200-330 cc/min at 9 bar which would seem to translate in 2.8-4.65 oz. in 25 seconds, not 2.5-3oz. Did I misunderstand something?

Finally. My wife is from Winston-Salem, NC. Nice area. Do you guys still do a lab on Mondays?

take care,
steve

PS: Great site

#4: Post by HB » July 16th, 2005, 9:20 pm

sru_tx wrote:Would you mind expanding on what you said?

Many have written about the importance of temperature stability through the shot and initial temperature accuracy. A PID'd Silvia essentially eliminates the latter issue; the former issue is what you're considering, i.e., reducing the temperature drop through the extraction. The value of such a modification presupposes the blend you prefer is temperature sensitive enough that reducing the drop from say 4F to 2F would produce a worthwhile improvement. For some blends, such as the renowned finicky espressos favored by David Schomer / Vivace, the benefit is undisputed. But what about blends that aren't so demanding temperature-wise?

In obsessing over ever-increasing temperature precision, we potentially overlook the new limitation that enters into the picture: The quality of the extraction itself. Mike explained this point well On the Bench when comparing body / mouthfeel of the shots from Silvia and Brewtus. Abe touched on similar points in his first post, The Next Breakthrough in Espresso Technology. Jim Schulman postulated pressure control improvements were behind the innovations of the Versalab M3 last year and Andy Schecter confirmed as much after talking with the inventor. If you read Chris Tacy's The Elusive Clarity in the Cup, you see that he's thinking about the (overlooked?) importance of pressure control too.

Hmm-m, maybe all this fussing about temperture control is so yesterday.

Would bumping the pump momentarily and then setting for a moment emulate a preinfusion by wetting the grounds under low(er) pressure?

I tried that long ago with disappointing results. At the time I blamed the pressure returning to zero for a moment, which is different than preinfusion for an espresso machine like a Microcasa, but admittedly I didn't invest a lot of time into it.

Looking at Jim's runoff method, I am questioning the calculation...

The manufacturer's stated variance makes this sort of a moot point; the runoff method is an estimate. If you're keeping Silvia and an estimation isn't satisfactory, I would install a brew gauge or invest in a pressure portafilter.

Do you guys still do a lab on Mondays?

Yes, over a year and still every Friday at 7:30am at Counter Culture Coffee. This past Friday we sampled Mike's Aficionado remix and Peter served us properly prepared iced coffee. It was a good time and I was once again late for work.