As mentioned in the introduction, I started with a Rancilio Silvia /
Rocky combo and upgraded to La Valentina / Mazzer Mini. Consistency with
Silvia was more of a challenge than it is with Valentina. Except for the
cool down flush, making espressos and cappuccinos is pretty much
hassle-free. Valentina produces very good results day after
day—convincing me that the consistency and temperature stability
of the E61 design is indeed as good as I’d heard. Despite all the
hullabaloo about electronic temperature controls you may read about for
some espresso machines (often referred to as “PID’d espresso
machines”), it is not difficult to consistently obtain nearly
one-degree accuracy during an extraction with a modest amount of
practice. If you’re not convinced, I invite you to read on.
How I Learned to Love HXs (Summary)
The how-to How I Stopped Worrying
and Learned to Love HXs covers temperature management for heat
exchanger espresso machines in detail, including charts showing the
in-basket brew temperature during an extraction. OK, OK, perhaps that is
too much detail for some readers! If you have already read
the article, skip to the next section.
Otherwise, allow me to summarize it, beginning with a few terms:
- recovery time - interval between consecutive shots
for the group to reheat to brew temperature (about two minutes).
- rebound time - pause after flushing but before
beginning the extraction (usually between 15-25 seconds).
- water dance - hissing and sputtering during the
cooling flush; the water settles down around 206°F.
Comparison of in-basket brew temperature of
La Valentina and La Marzocco three-group
commercial espresso machine; the La Marzocco brew temperature
initially rises faster
because its rotary pump pressurizes the group almost instantaneously
The rebound time affects mostly the first third of the shot,
producing what I call the HX hump, which is the momentary
rise above the target brew temperature. Lowering the boiler pressurestat
setting increases the rebound time (e.g., rebound time is approximately
25 seconds at 0.9 bar and 15 seconds at 1.1 bar). The flush amount
affects the overall brew temperature.
Does this sound overly technical? Well fortunately there’s an
easy-to-remember guideline you can use until you've developed an
intuitive feel for the correct timing. Quite simply, the temperature
drops approximately one degree per second during the cooling flush after
the water dance stops. To make this point clearer, see this video clip showing the temperature of the water exiting the group
of a heat exchanger espresso machine during a cooldown flush.
To warm up the portafilter prior to an extraction, I prefer to start
the grinder and then remove the portafilter halfway through the flush,
which gives me about 40 seconds to fill and tamp. Despite my noting
specific times in seconds, to be honest, I haven’t bothered with
timers or measuring the flush amount once I developed a good feel for
when it’s going redline; you too will get the hang of it after a
few weeks with Valentina.
Why the E61 Design is So Popular
The E61 group has a well-deserved reputation for being a
“forgiving” design. Part of this forgiveness is due to the
impressive temperature stability discussed earlier and graphically
demonstrated by the last two-thirds of the temperature profile above.
There is a slight difference between the shapes of La Valentina and La
Marzocco’s temperature curves and it does have a minor effect on
the in-cup result. If you are the type of home barista that enjoys
experimentation, you can “work” a blend’s flavor
characteristics by manipulating the rebound time as documented in HX cooling flush in detail.
On the other hand, if you’re the keep-it-simple type, following
the shorthand guidelines in the previous section will produce very good
Another characteristic contributing to the E61's forgiving nature is
its initially slow rise in brew pressure, known as progressive
preinfusion. The slow increase in pressure allows the coffee puck
extra precious seconds to expand, thereby closing micro-fissures that
could otherwise lead to channeling. You can also see another effect of
this deferred pressure rise in the temperature profiles
above—Valentina’s temperature increases more slowly because
the brew chamber fills gradually during preinfusion. Also note that the
E61’s initial temperature starts higher (around 185°F). The
E61’s thermosyphon circulates water more aggressively from the
heat exchanger towards the grouphead compared to commercial groups,
resulting in a higher starting temperature.
All technical minutia aside for a moment, the happy consequence of
the E61 design is that Valentina will produce a reasonable extraction
even if the amount of coffee, tamp, or grind are less than ideal
(however, if you do run into problems, look to the Extraction
Troubleshooting Checklist for suggestions on correcting them).
Pulling Shots by the Numbers
Below are the steps for making your first espressos. Let’s
assume that you’ve adjusted your grinder for a reasonable 25-27
- Allow La Valentina at least 25 minutes to warm up.
An accurate and stable brew temperature relies on the entire brew
pathway being up to temperature. If you prefer not to leave La
Valentina on 24/7 and you’re rushed in the morning, consider a
timer to preheat the machine before you wake (I recommend the
heavy-duty programmable Intermatic digital timer model DT17C, available at Home Depot for less than
- Start the grinder and press the brew button to begin the cooling
flush. Remove the portafilter after about 10 seconds, dry out the
basket, and then fill and tamp firmly.
Generally I measure by volume, but sometimes use a precision scale
to weigh out the beans and run the grinder until empty. I found that
17.5 grams of coffee beans / a small heaping basket full of grinds
worked best (a level basket holds around 16 grams before any settling).
Smooth out the grinds to an even bed of coffee as described in Dose, Distribute, Tamp. Repeat.
It is important to have some clearance between the dispersion screen
and the top of the puck. This facilitates the even distribution of
water over the surface and allows the puck to expand upward to meet the
dispersion screen as it absorbs water. You can quickly double-check
clearance by gently placing a nickel on the top of the puck, drying the
dispersion screen, then locking in and removing the portafilter. The
puck should only show a faint impression of the coin if the clearance
The rebound time after the cooling flush is less than one-half
minute at a pressurestat setting of 1.1 bar. If you remove the
portafilter about halfway through the flush and start to prepare the
basket, that doesn’t leave a lot of time to dose, distribute, and
tamp before you should start the extraction. Alternatively, if you
prefer to keep the portafilter in the group for the maximum time and
work at a gentler pace, try removing the retention clip from the
portafilter so the basket drops in and removes easily. Then you can
tamp at your leisure while the portafilter remains in the grouphead.
Once the basket and coffee are ready, a quick turn to remove the
portafilter, flush, drop in the basket, then back in the grouphead.
Hint: Listen for the hissing of steam and gurgling of boiling
water before locking in the portafilter. Continue drawing water for
about five seconds after the stream has settled down, for around six
ounces total. Depending on the blend and your taste preference, the
recovery time after the cooling flush is somewhere between 15 seconds
(puck surface temperature briefly peaks about one or two degrees
Farenheit above target brew temperature) to 35 seconds (puck surface
temperature peaks around four degrees above brew temperature).
- Lock in the portafilter and toggle the brew button to start the
Take a moment to rinse the grouphead by loosely locking in your
second portafilter with backflush disk and running the pump while
slowly jiggling the portafilter handle back and forth. This
“wiggle-rinse” will wash most of the loose grinds off the
grouphead and dispersion screen and over the sides of the portafilter
into the driptray. Be careful not to splash yourself and watch for hot
water running down the portafilter handle!
Remember to relock the portafilter back into the grouphead to keep
At the end of a session, I also recommend a quick water backflush to
clear the pathway from the grouphead to the pressure relief valve that
empties into the back of the driptray. Refer to Espresso Machine Cleaning - Why, How, and When
for more details on a cleaning regime that applies well to La Valentina.