More questions about flushing and cold? Expobar brew temps

[gordonm]

I have been playing with my new Expobar Pulser this weekend, trying to figure out where I am in temperature space. I've had my machine for about 2 weeks now, burned through well over 3 lbs of beans, and am presently on my second lb of Classic Espresso from Rocket Coffee (which, Larry says, has a ~201.5 F target temp). So far, most of my pulls have tasted sour to me. My grind, dose w/ WDT, and tamp routine seems fairly consistent now, and I get some nice looking pulls out of my bottomless PF. But, it still seems like the coffee is sour.

Now, I'll be the first to say that I am NOT a super-taster, nor a coffee expert, and it's entirely possible that I don't know the difference between sour and bitter (too cool or warm?) espresso. I will say however, that so far I haven't had anything that tasted remotely ashy or burnt. And, the best adjective that comes to mind for me is sour. So, I began to suspect that despite everything I've read about Expobars, that mine might be running cooler than expected, and that my flushing routine (end of "dance", plus 5 sec; which usually takes ~8oz) was leading to too cold of a brew temp.

Since I haven't had time to take Larry from Rocket Coffee up on his generous offer to use his Scace TC PF to dial in my technique, I thought I might try measuring the water right out of the group and just see what happens with different flushes.

Here's what I've found so far using a TC and TC meter that is on an Acorn pH meter (this is for my other "hobby" winemaking. If you think making good espresso is hard, try home winemaking in AZ!)
I'd appreciate anyone's comments on my observations. Unfortunately, I don't know what type of TC it is (I suspect K-type), but it is calibrated properly (at least at 0 and 100 C) and has a reasonable response time (about 10 sec to stabilize). And, I measured the temp of 2 oz of water that fell into a styrofoam cup.

After 30 min warmup, 8oz flush, 30 sec rebound: T=87.4°C
5 min recovery, 6oz flush, 20 sec rebound: T=89.2
3 min recovery, 2oz flush, no rebound: T= 90.1
1 min recovery, 2oz flush, 30 sec rebound: T=90.5
3 min recovery, 2oz flush, 1 min rebound: T=91.1

Now, I know this is just an average technique, and that I lose some heat as the water falls out of the group into the cup, but shouldn't I be getting closer to 93 or 94 degrees? Or is all this just a pointless waste of time?

I did pull a real shot after all of this, about 5 minutes recovery, with only a 2 oz flush, a 30 sec rebound, and it didn't taste sour! So, is it possible my Expobar is acting more like a cooler machine?

I appreciate any comments!
Thanks,
Gordon

[miKe mcKoffee]

Unfortunately the temps are kind of meaningless and wouldn't correlate to actual temps at the puck. Plus pulled with no puck resistance so temps would drop off faster than at shot flow. Suspect you'll see very different temps same timings when you get a hold of the Scace Thermofilter.

The good news and the part that counts is your last paragraph! Short flush & 30sec rebound got you in the ballpark of where you need to go. Adjust by taste from there.

It does sound like your Pulser is on the cool side. What's your boiler pressure? Steam power ok?

[gordonm]

It does sound like your Pulser is on the cool side. What's your boiler pressure? Steam power ok?

Thanks Mike. I kinda suspected the temp's were to low to be realistic or useful.
To answer your question about pressure, I don't know. I have no way to measure anything right now, thus my foray into measuring temp's out of the group. The steaming power seems to be pretty good as I can get great microfoam even with the single hole tip, but again, I don't really have anything to compare it to.

Are there any other characteristics, visual or otherwise, that would let me know when I'm too hot or too cold? IIRC, I read that espresso brewed too hot leaves a dark, oily rim around the edge of the cup? (yet another thing I've never seen)

As far as the taste goes, I'm going to play a bit more tomorrow with a "warmer" flushing technique and see if things improve. If so, then I'll really be curious to know what the temp's are like using a more useful technique. I'll also remind myself that you can't believe everything you read . . .

Thanks again,
G.

[Bo]

I'd like to know what happened to my Expobar Pulser. Milk steaming warm up temp and time have fallen dramatically. I used to get hot steaming temps quickly after a 20 min. machine warm-up. I'm also getting lower temp espresso pulls(120F) in the warmed cup. Are there simple adjustments for these problems? Are these machine turning out to be unreliable? Mine is 6 months old and used 4 times a day. Your help and links are appreciated.

[HB]

Milk steaming warm up temp and time have fallen dramatically.

My first thought is scale. Below are some threads with background info and pictures:

• Sputtering e61 & HX scale build-up - Cured!
• Boiler temperature wont go past 190
• Water, Scaling and Descaling with HX machines?

It's also possible that your pressurestat is acting up, though they tend to either work or not. Unfortunately the Pulser doesn't have a boiler pressure gauge.

[Bo]

I got instructions from WLL on dialing up the pressure stat. The PS they are referring to is in machines prior to Jan '06 or might be mixed throughout models. My PS (a different type) has a click wheel(no center mark?) that was easily adjusted by hand.I turned it in 1/4" increments and am checking with the temp outputs into a heated cup for milk and espresso. Direct hot water coming out of the brew head(no portafilter) is up to 170.
Tea outlet easily 200, steam wand heats milk to 160 now. Are these temps about right? No pressure reading available.
Does anyone know what the deal is with the "added mineral conditioning filter thing" that is attached to the water inlet hose?
I've heard that the beads inside can end up in the boiler and damage it.
On another note,the metal exterior is prone to corrosion and pitting(in the coffee area). I use MAAS to keep it rust free.

[HB]

Tea outlet easily 200, steam wand heats milk to 160 now. Are these temps about right? No pressure reading available.

Sorry, measuring the water temperature doesn't accurately determine the boiler pressure because it changes depending on how much water you flush. You could try attaching a (temporary) gauge to the steam arm. I've read of some Expobar Pulser owners using hose clamps, high-temperature reinforced rubber tubing from an automotive parts store, and a tire gauge to measure from the wand, but I've never tried it myself (standard disclaimer: steam and hot water under pressure are dangerous; modifying your espresso machine in any way risks scalding, explosion, personal injury, property damage etc.).