So, I'll admit it. I bought this machine that sat in some dude's garage for who knows how long without knowing the first thing about commercial espresso machines. I'd never even used one before. But, the deal came up--$500 for a Rancilio L7, MD40 grinder, and SS base. I couldn't pass. Through the process of tearing down, descaling, and rebuilding the machine I learned more than I ever thought I would. It was a great experience and I'm glad I did it.
The L series is the predecessor to the much-discussed S-series. The L7 is the automatic (flowmetered) version of the line and takes a direct plumbed water line and drain. Knowing what I know now, the L6 (semi-auto, plumbed) would have been perfect for me, because I have never used the volumetric buttons. But, the manual button has gotten more than its share of use, for sure.
Like all heat exchanger machines, this one has a single boiler with a heat exchange unit within. The machines take some instruction to understand and use well, but once the concept is grasped they are simple to pull good and great shots with. There is a reason that this boiler setup has been in use for so long and continues to be found in many, if not most, commercial machines. They work. They do a good job. Let's not expect the consistency and temperature stability of a dual boiler, PID modified unit, but they are very solid performers.
After finishing the refurb I've used several other commercial machines in a professional setting. Comparatively speaking the L7 is a good performer. It simply doesn't have the steam that a larger boiler might offer, and certainly not what an LM dual boiler setup does, but it sure beats my old dual-use boiler Gaggia. It's not an LM Linea or GB5, but it has ample steam and temperature stability to get the job done.
The boiler is relatively small, though appropriately sized for a single group machine. I don't recall the precise volume of the boiler, but I believe it is ~2.5L. The small boiler is great in terms of its ability to cycle up to heat on its modest 110v input. However, the limitations of size are quickly reached when entertaining. Multiple steamed milk drinks and Americanos take their toll and temperature fluctuations can be problematic.
The boiler pressure variance of .2BAR is somewhat troubling as well, from a theoretical standpoint. The variations in temperature in the boiler and consequently the heat available to be transfered to the brew water in the heat exchanger cause swings in brew water heat. Usually my pre-shot HX flush is paired with a burst of steam from the steam wand. This combination is usually enough to trip the pressurestat into cycling on. Then I wait for the pressure to nearly reach my 1.1BAR setting before beginning to brew and steam my milk. This process usually leaves the heating element in the on cycle until I've finished preparing my drink. It's a nice little trick that allows stability to be reached where fluctuations might otherwise occur.
I've had little issues here and there with a few leaky gaskets that I need to replace and a sometimes tricky boiler level sensor. The sensor especially has been troublesome. I went through a period of time when the boiler kept filling beyond the sensor point until the MAX level or above. This is obviously a headache for temperature and maybe even safety reasons. Less importantly, there was not ample room in the boiler for a significant head of steam to build, so milk drinks were out for a week or so. Then the issue resolved itself. I'm not sure what was up, but it hasn't done it for quite a while, so I'm not asking questions.
Other little quirks that may have been resolved in later Rancilio singl boiler product lines have to do with the engineering of the interior. All of the plumbing goes into the top of the vertically oriented boiler. The boiler is essentially a big brass cup with a sealed cap on the top. The heating element enters through holes in the bottom and the sightglass loop runs in and out of one side. Other than than, all of the plumbing, the thermostat, and the pressure release valve are grouped on the top. This is great for economy, but terrible in terms of accessibility. I had a bear of a time loosening and tightening some of these nuts when I was refurbing the unit. It would have been nice if they had been easier to access with standard tooling.
I'm not a huge fan of the dispersion block on this one either. I tend to observe a little greater flow on one side than another and there is no apparent blockage. It just seems to be how it's built. Marzocco's vertically fed brew water makes more sense than this.
Otherwise, the unit is quite solid and definitely more than adequate for home use. This is a coffee cart machine, or one perfect for a restaurant setting. It's really a great unit and I'm proud to own it. I've heard of and seen other units in the L series floating around ebay and craigslist and I highly recommend it to anyone who isn't afraid to get his or her hands dirty. ...or to spend the cash to have it professionally overhauled.