The espresso machine was invented at first for commercial use in coffee houses and cafe-bars. However, the domestic demand grew bigger than expected and the manufacturers responded with the semi automatic espresso machine.

The semi automatic machines gained quick popularity as they were so much easier to use. The user still controles the begining and the end of the brewing process, but the machine is the one that develops the water pressure. The semi automatic espresso machine has several versions where the portafilter makes the difference. Thus,

• commercial style portafilter is 58 mm in diameter (the same is used on 'prosumer machines', which are a kind of hybrid between home use and professional); with this portafilter, the quality of the espresso cup depends on the grind and the tamp; you also need to buy a tamper;
• pressurized style portafilter (49mm to 54 mm diameter) creates itself the necessary resistance for the water to pressurize the coffee bed, and is not so dependend on grind size and tamp.

The semi automatic espresso machine features a heat exchanger boiler (with two thermostats and a swich knob), that allows the operator to control coffee extraction and steaming. Although there is a waiting time required to switch between the two operations, the barista holds some techniques to reduce this gap. Also, the ultimate models include seccondary heating elements placed inside the boiler that automaticaly reduce these waiting times.

Automatic refill is a characteristic feature for commercial espresso machines, not available with home-use machines.

The Brands

• Capresso Espresso Machine, model 'Pro' owns a 40 oz. water reservoir and is one of the best budget-choices you can make, ranging between $150 and $250; also features a FrothXpress attachment (32 oz. cold milk container)
• Gaggia Espresso Machine - The semi automatic model 'Classic' ($400) features standard 58mm portafilter, temperature stability grouphead, quick warm up times boiler and rapid recovery times
• Francis Francis Espresso Machine - casting several episodes of 'Sex And The City' (probably due to its dandy-look), is available at a price worthy of a movie star: around $700
• Rancilio Silvia Espresso Machine - now that is a semi-professional model that made quite a career on the web, see the folowing blog to have some fun; The Rancilio Coffee Grinder Rocky is its best counterpart; Rancilio Sivia is priced around $800;
• Saeco Espresso Machine - Model 'Classico' ($300) comes with pressurized portafilter, a Saeco patented system, and a 80 oz. water reservoir (that means you can brew 40 cappuccinos before refilling)
• Solis Espresso Machine - Model 'Crema SL 70' ($375) poseses one of the biggest boilers for its class

Some not so reviewed brands for semi-automatic machines are: Expobar, Krups, La Pavoni, Isomac, Napresso, Pasquini, Salvatore