La Marzocco Espresso Machines Guideline
The La Marzocco espresso coffee machines work by forcing hot water under high pressure
through finely ground coffee held in a portafilter. The brewing process uses several key
components to accomplish this process.
Nearly every other espresso machine manufacturer uses a single boiler and heat exchanger
located inside the steam boiler. Water for brewing espresso is solely dependent on the
temperature of the single steam boiler and this creates inconsistent brewing and steaming
conditions, thus producing inconsistent drinks.
The La Marzocco espresso machine uses a unique two-boiler systems to isolate and perform
operations in the best possible conditions.
The rear boiler is dedicated to the steam and hot or tea water functions.
The front boiler has the sole purpose of providing brewing water at the correct temperature
and pressure for the coffee the barista is going to brew.
These temperature and pressure parameters are adjustable independently of any other
function of the espresso machine. They are also consistent though most any level of operation.
HOW DOES IT WORK?
Cold, filtered water enters the brewing boiler through a pump which raises the water pressure
to 9 bars to allow the water to flow through the finely ground coffee.
Then the water in the boiler is heated by a heating element, which is controlled by a
Temperature probe connected to a CPU which control and sends power to the element when
the water temperature is low and shuts off power to the element when the water is at
operating temperature.
This means the temperature of the coffee brewing water can be set precisely depending on the
operator's taste, the roast or blend of the coffee used.
When the barista puts the portafilter into the brewing group, it forms a watertight seal
between the portafilter and the group gasket.
When the user presses the brew switch, a solenoid valve opens and the pump generates
pressure to force the hot water from the boiler through the group and the diffusion screen and
screw, then into and through the ground coffee, producing the desired volume of espresso,
which is brewed into heated cups or shot glasses.
On automatic (AV) models, the water is measured by a flowmeter.
Table of Contents
Related Manuals for La Marzocco Strada
Summary of Contents for La Marzocco Strada
- Page 1 La Marzocco Espresso Machines Guideline The La Marzocco espresso coffee machines work by forcing hot water under high pressure through finely ground coffee held in a portafilter. The brewing process uses several key components to accomplish this process. Nearly every other espresso machine manufacturer uses a single boiler and heat exchanger located inside the steam boiler.
- Page 2 Since the La Marzocco is built to a different principal than other espresso machines, let’s look at the individual systems that make up the entire machine.
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Page 3: Flow Meter
4. FLOWMETER The flowmeter measures the volume of water passing through the groups. The flowmeter consists of an impeller or wheel that contains two small magnets, and a body or housing that contains a precision orifice or jet that controls the amount of water that can flow into the flowmeter. -
Page 4: Safety Relief Valve
The expansion valve is adjusted by increasing or decreasing pressure on the spring by turning the brass barrel. It should begin to drip at 10-11 bar and release fully above 12 bar. 8. SAFETY RELIEF VALVE The safety relief valve relieves boiler pressure at 1.8 bar thus preventing the steam boiler from over-pressurizing. -
Page 5: Heating Element
The thermostat contains an adjustment screw that adjusts the distance the piston must travel to activate the switch, thus adjusting the temperature. To increase temperature turn the screw clockwise; to decrease turn counterclockwise. Each 1/4 turn of the adjustment screw represents approximately 2 degree Celsius temperature change. - Page 7 La Marzocco La Marzocco Machines Basic Guideline Machines Basic Guideline What should I do to maintain my espresso machine?
- Page 8 1. Clean the group heads daily. A. Gently remove the basket from the portafilter, using a small flathead screwdriver. Complete this maintenance sequence daily for each group and portafilter. B . Remove basket. Place portafilters and baskets in a PuroCaff solution (1 spoon every 1/2 liters).
- Page 9 E. Rinse blind filter under group head until water flows clear. F. Clean remaining coffee grounds from the portafilter engagement area with a cleaning brush. G. To remove residual detergent, install portafilter with an empty blind insert into the group and flush for five seconds. Repeat ten times.
- Page 10 I. Now remove baskets and inserts from the PuroCaff solution and rinse thoroughly. L. Verify that the basket spring is seated in position. Reassemble portafilters and install at each group. 2. Clean the diffuser screens and groupheads daily. A. Remove the portafilter from the group.
- Page 11 C. Gently scrub the diffuser and portafilter gasket and portafilter engagement area. D. Dip a bar towel into the PuroCaff solution and thoroughly wipe down the grouphead area. E. Remove diffuser screen and screw from solution. Rinse thoroughly in clean water. F.
- Page 12 Replace portafilter gaskets A. Using a stubby flathead screwdriver remove the diffuser screen and screw assembly. B. Now, using a sharp awl or pick pierce the gasket surface. (NOTE: Old gaskets may harden, resulting in a more difficult task.) Pry the gasket from the group head and discard.
- Page 13 F. Seat the gasket by partially inserting one side of the portafilter then the other. G. Now, completely engage the portafilter. (NOTE: If the gasket is not fully seated, greater than normal pressure may be required to engage the portafilter.) Reinstall the diffuser screen and screw once the gasket is securely in place.
- Page 14 Relieve an airlock in your group. A. Turn power off. B. Remove top panel. C. Loosen bleeder screw, until water bead appears. (NOTE: Slowly turn the bleeder screw for approximately 1/4 turn. It is critical not to remove the screw completely.) D.
- Page 15 Check the flowmeters (performed by authorized tech) Check the group valves (performed by authorized tech)
- Page 16 Inspect brewing system for leaks Inspect for group valve leaks at the discharge fitting… …and excess leaking from the expansion valve. A "slow but consistent" drip is normal. Adjust or replace as required. (see Machine Guideline topic # 7 – Expansion valve) Service the steam valve every three to four months (performed by authorized tech)
- Page 17 Inspect pump and expansion valve pressures Adjust the pump using a screwdriver while extracting espressos until the dispense gauge reads 9 bars Now, while group is off, but heating element is on, turn expansion valve until the dispensing pressure reads 12 bars.
- Page 18 Coffee is best brewed at 9 bars of pressure. Higher pressure results in noise, caused by the expansion valve releasing excess pressure. The expansion valve allows the excess pressure from water heating to be bled off to prevent damage to the brewing system components. It is very important that the expansion valve always be set to 12 bars.
- Page 19 My machine doesn’t steam Steam tip is clogged Clean steam wand tips A. Clear steam tip holes with a wire or sharp awl B. Wipe wand and clear by running steam through the tip for several seconds.
- Page 20 If steps A-B are unsuccessful, proceed with: C. Loosen tip using an open-end wrench and remove. D. Mix a solution of Purocaff and hot water. Soak tip for 10-15 minutes. E. Rinse the tip and wipe clean. F. Wrap the steam wand threads with a short length of teflon tape.
- Page 21 Glossary autofill system The components responsible for maintaining the correct level of water in the steam boiler. These include the autofill solenoid, autofill probe, and control box. ball valve, steam the valve used to shut-off the flow of steam from the steam tank to the steam valve assembly and wand.
- Page 22 The brewing head of the La Marzocco. It is completely filled with water to allow the convection of heat within and provide a high level of thermal stability for espresso brewing. impeller, flowmeter The six bladed wheel that spins within the flowmeter body.
- Page 23 power switch A three-way switch that applies power to the espresso machine. During start-up, the first position provides power to the dosing and fill system. When the machine is full, the second position is engaged to provide electricity to the heating elements. pressure gauge, double scale Measures the steam and brewing pressure in bars.