The owner's manual included with the machine was a photocopy of the original. It was well translated from Italian, but contained little beyond obvious instructions. The box came with one page of quick-start instructions that describes the machine's initial boiler auto-fill cycle and warns about shipping problems that may crop up (loose connections, boiler water splashing about inside the machine during transit, etc.).
The owner's manual claims fifteen minutes to warm up. The boiler will click off long before that time expires, however the portafilter will be barely warm. Consider twenty-five minutes as the minimum recommended time for passively warming the grouphead and portafilter; thirty minutes is more than adequate. If you are too rushed in the morning to allow a proper warm up and don't want to leave the machine on continuously, you can use a heavy-duty timer to turn it on before you get up for breakfast.
Once the machine is fully warmed, the exposed portion of the E61 grouphead is hot to the touch. Not so much that a casual brush against it will burn skin, but enough to get your attention quickly. The hottest grouphead surface temperature that I measured was 185°F. Despite the hot exposed grouphead, none of our curious little ones have ever burned themselves on it. To be certain, I did remind the kids "hot! hot! don't touch! ouch!" if they even looked in the general direction of the grouphead. They've adapted quickly to Valentina and the routine of preparing espresso—in fact, my youngest often insists on "helping" by pulling the doser handle and pushing with both his hands overtop my hand on the tamper (it's a "flat-er" to him). But I digress...
The warming tray is very effective and will warm the cups in about 45 minutes, thanks to the 1.2 liter copper boiler and slotted top that allows the heat to rise. The tray narrows towards the back. It can fit two small cappuccino cups side-by-side in the back row and two rows of three espresso cups in the front.
You'll hear a little gurgling sound coming from the machine a few minutes after it first starts up. That's the noise of water boiling before the vacuum breaker has closed off the boiler. A last few fizzles as it snaps shut, then there's no worries about false pressure (otherwise you would have to initially bleed pressure through the steam wand so the boiler pressure gauge works correctly).
Adjusting Brew Temperature
As discussed in Fine Tuning HX Brew Temperature, adjusting the flush amount by observation and taste is more important than the precise boiler pressure setting for this class of espresso machines. The lower the pressurestat setting, the more time before the water in the heat exchanger goes over the target brew temperature; I recommend a setting of 1.1 bar (measured from the top of the heating cycle) as a good tradeoff between ample steam production and reasonable recovery times.
La Valentina's boiler pressure adjustment is easy. Beneath the cup warming tray is the pressurestat—it's the black box in the back right corner. Underneath its cover is a large adjustment screw with +/- arrows denoting the correct direction. Notice the Sirai pressurestat is commercial quality. The extra set of electrical contacts can be pressed into service for quick repairs if the pressurestat fails because of carbon build-up or pitting due to arcing. Of course this sort of failure is infrequent in a home environment, but it's nice to know that the pressurestat can be repaired easily (non-commercial pressurestats are generally sealed and cannot be repaired).
The pressurestat allows for very fine adjustments. For example, approximately six half-turns of the pressurestat screw corresponds to a mere 0.1 bar change in pressure.
Adjusting Brew Pressure
The expansion valve, which determines the maximum brew pressure, was initially set at 12 bar (this valve is also called an over-pressure valve or "OPV"). If the pump is unregulated, it can produce an overextracted, bitter shot. Adjusting it down to nine bar helped the consistency of my shots immensely, especially when pulling ristrettos. You'll need a portafilter pressure gauge to adjust it because there is no brew pressure gauge. I recommend asking 1st-line to do the adjustment before shipping.
Valentina's expansion valve is an industrial-grade fluid control valve, rated for two years of continuous use. That translates into forever in a home environment. The expansion valve allows for very fine adjustments. The one-bar adjustment of some non-commercial expansion valves corresponds to a slight turn of a small screw; Valentina's is finely adjustable and is done simply by turning the end of the expansion valve itself. This means that you have a lot of control without fear of overshooting the desired maximum pressure by a slip of the pliers.
Inside La Valentina sports several commercial components. This includes the Gicar auto-fill controller and Sirai pressurestat. I also appreciate the thoughtful layout of the machine. The cup warming tray comes off with four screws and the U-shaped back cover with six screws. This exposes the entire working innards in less than two minutes. The construction of the boiler, wiring, and components is formidable. The only false note is the framing itself. The designers chose a "uni-body" construction, where the structural integrity depends on the strength of the wrap-around casing to offer support. That is, unlike Silvia whose components attach to an iron-welded frame, Valentina's are mounted on folded zinc-plated sheet metal. Admittedly this is a relatively minor point that speaks to my engineering side rather than practical necessity.
There are other considerations that reveal Valentina's semi-commercial pedigree. A cutout under the boiler to enable easy replacement of the boiler element, should the need arise. There is a similar cutout under the driptray area to allow for installing a drain. Combined with the high clearance, I was able to install a drain without cutting into the countertop.