This guide explains how to install the COWEET USB-powered shot timer on a La Marzocco Linea Classic 2 Group espresso machine. The installation involves opening the upper access panels, locating each group's brewing solenoid valve, securing the timer sensor to the relevant solenoid coil, routing the sensor cables safely, and connecting USB power. No connection to the machine's mains wiring or control board is required for the COWEET USB-powered sensor version.
Model note: The original Linea Classic and the newer Linea Classic S have differences in panel construction and internal layout. The steps below describe the general access and sensor installation method, not a verified screw-by-screw teardown for every production year. If your machine differs from the diagrams, contact COWEET with a photo of the interior before proceeding.
Before you begin — safety
Commercial espresso machines contain high-voltage electrical components, pressurized boilers and very hot pipes. Turn the machine off at its main switch, disconnect or isolate its mains power, allow it to cool completely, and do not touch any electrical terminals. Access to internal panels should be carried out by a qualified espresso-machine technician. Do not loosen any plumbing connections, valve retaining nuts, solenoid coils, boiler screws or pressurized fittings. The sensor mounts externally: there is no need to dismantle the solenoid valve.
What you will need
- COWEET shot timer, sensor lead(s) supplied with your kit, and USB power cable
- Appropriate screwdriver or hex key for your particular machine's cover fasteners
- Removable cable ties or cable clips
- A suitable USB power supply located outside the machine
- A clean dry surface on each target solenoid coil for the supplied sensor mounting method
Step 1 — Open the top access area
- Switch the machine off, isolate mains power and let the machine cool.
- Remove the cups and lift off the top cup-warming tray/grate as appropriate for your machine.
- Remove the relevant upper group cover or service panel fasteners and lift the cover away carefully. Retain every screw and washer for reassembly. Do not open the sealed group cap or boiler itself.
- From above, inspect the area behind/around the left and right brewing groups. You should be able to identify the group plumbing and electrically actuated valves.
La Marzocco's Linea Classic quick-start guide confirms top access by removal of the group cover and cup tray. The official Linea Classic S parts catalog includes exploded illustrations for the group, group cap, body panels and valves. These are references for identifying parts; they are not instructions to dismantle the group cap.
Step 2 — Identify the brewing solenoid for each group
Find the brew (3-way) solenoid valve associated with the left group and then the matching valve for the right group. Look for an electromagnetic coil fitted around a valve stem, with electrical leads connected to the coil. Follow the plumbing and the valve identification in the parts catalog rather than simply choosing the first black coil you can see.
Important: There may also be solenoid valves for automatic boiler filling or hot water. These are not the correct detection points. The exact orientation and location can vary between Linea Classic generations. If uncertain, photograph the upper machine interior and ask COWEET to confirm both target coils before attaching the sensors.
For identification, see the official parts catalog — “Fittings and Valves”, “Coffee Boiler – Group”, and “Coffee Boiler – Group Cap”.
Step 3 — Attach the timer sensor(s)
- Check that the target brew-solenoid coil is cool, dry and clean.
- Place the supplied COWEET sensor against the outside surface of the brewing solenoid coil, following the supplied sensor's attachment method. Do not remove or loosen the coil or disconnect its wires.
- For a two-channel kit, install the left channel sensor on the left group's brewing solenoid, and the right channel sensor on the right group's brewing solenoid. Keep both leads identifiable. If your kit has only one sensor, it monitors only the group to which that sensor is fitted; contact COWEET about a second-channel configuration.
- Secure the sensor lead so that movement or vibration cannot pull the sensor away from the coil. Never fasten anything to electrical contacts.
The sensor senses brewing-solenoid activation; it is not powered from the espresso machine's solenoid wires. Do not splice into the valve wiring or attempt to power the timer from the machine.
Step 4 — Route the cables and position the timer
- Lead the left and right sensor cables along an existing safe service route toward the desired timer location. Use the same general internal cable-management path as the machine's original control wiring only where this can be done without disturbing it.
- Keep cables away from the steam boiler, heating elements, exposed terminals, sharp edges, moving parts and high-temperature copper tubes.
- Use removable cable ties or clips on suitable cool, fixed mounting points. Leave a little service slack near each sensor.
- Bring the leads out through an existing suitable opening or protected gap. Do not drill the machine, pinch cables under a sharp cover edge, or compromise any safety shielding. If no suitable exit path is available, ask a qualified technician to select one.
- Mount the timer in a convenient, dry location outside the machine, away from steam and splashes. Route the USB supply cable to an external USB power adapter. Do not place a consumer USB adapter inside the espresso machine.
Step 5 — Reassemble and test
- Before closing the panels, verify that both sensors are secure, all original connectors remain undisturbed, and none of the new cables can touch hot or live components.
- Refit the covers and top tray without trapping the wiring. Ensure no original screws or panels are omitted.
- Once fully reassembled and safe, restore machine power and connect the timer to external USB power.
- Start a short water-only brew cycle on the left group: the corresponding timer channel should begin when the brewing solenoid is energized and stop when brewing ends.
- Repeat on the right group. Confirm that each sensor operates its intended channel.
If the timer does not respond, turn the machine off and isolate power again before reopening any panel. Confirm the sensor is attached to the correct brewing coil, is securely held in place, and is properly connected to the timer. For a two-group system also verify the left/right channel wiring. Never reposition a sensor while the machine is energized.
Frequently asked questions
Do I need to connect to the La Marzocco control board?
No. For the COWEET USB-powered sensor version covered here, the sensor is placed externally against the brewing solenoid coil and the timer receives its power separately via USB.
Do I need to dismantle the solenoid valve?
No. Do not undo the coil retaining nut, valve body, tubing or group-cap fittings. Only the relevant outer access covers need to be opened to reach the coil.
Where should the USB power cable go?
Keep the USB supply and adapter outside the machine, in a dry protected area. The cable may be routed through a suitable existing protected exit point without pinching or heat exposure.
What if I cannot identify the correct coil?
Send COWEET a clear photo of the opened top access area showing both groups and the solenoid valves, together with your Linea Classic production year (if known). We can help identify the appropriate attachment points for your exact machine.
Additional references
- La Marzocco — Linea Classic Quick Start Guide
- La Marzocco — Linea Classic S Exploded Parts Catalog
- COWEET — Linea Mini Timer Installation (related concept; a different machine)
This is a draft guide. Specific coil placement and cable exits should be visually confirmed on the customer's exact Linea Classic 2 Group before the guide is published as a model-specific instruction.