Coffee Solenoid

What is a Coffee solenoid?

A solenoid valve is an electrically controlled valve.

The valve features a solenoid, which is an electric coil with a movable core (plunger) in its center. In the rest position, the plunger closes off a small orifice. An electric current through the coil creates a magnetic field.

In simplest terms, when you turn on a switch, current flows to the coil and it becomes magnetic. This caused the plunger to retract very quickly against a spring, this causes the 9 bars of pressurized water to continue to flow. When the switch is turned off the plunger goes back to blocking the circuit.

These valves become blocked with a mineral build-up or in the most neglected cases a build-up of coffee oil in the group solenoid. Backflushing prevents a coffee oil buildup in the group valve and descaling prevents the valve from getting blocked by mineral buildup. 

How do I remove a coffee machine valve?

A top tip to remove the valve is to insert your Allen key into the hexagonal screw and tap the Allen key with a spanner. This will break the seal caused by the mineral buildup. A swift tap anticlockwise will loosen the most stubborn screw. ''Lefty loosey - Righty tighty'' applies here. The silicon o ring must be in place and should be new. Make sure when replacing the valve the holes are aligned otherwise the valve won't work and you will have to redo it.

Why is my coffee machine valve not working?

Solenoid valve malfunctions are common in hard water areas and tend to fail when they become blocked by mineral buildup inside the valve. Occasionally the coil may rupture on volumetric machines - when the button is pressed but no water, the whole valve should be replaced. Parker Cime and Lucifer are the most common brands and are made in Italy. The best valves have a ruby red Viton plunger inside the nucleus of the valve - this last so much longer than the rubber grommet.

The main areas where you will have an electro valve is the coffee group, electronic hot water, and water inlet of a plumbed machine.

• Coffee group: When no water comes from the group, you may get steam but no water.
• Water inlet solenoid: Water is not getting to the boiler due to blockage, you will have coffee water but the boiler is not filling - typically blocks when roadworks occur or town water refills in the summer letting rust or sediments into water supply and blocks both the valve and damaging the pump. Both the pump and inlet valve will need to be replaced.
• Hot water solenoid: When you press a button for hot water and you get just stem or no water - this gets blocked with lime over time and needs to be replaced.