Water inlet valve

In Most coffee machines you will find a water inlet valve or a combination of 2 types of systems. You used to have 3 types of water inlet valves

Manual inlet valve;
Solenoid inlet valve with manual overrride;
Solenoid inlet valve.

Manual inlet valve

This type of water inlet valve is barely found anymore. This was caused with the invention of the level regulator. Because of the level regulator a solenoid valve needs to be installed, seen the valve becomes electronically controlled. You would find this system on coffee machines before the 1990's. depends offcourse on which model you had.

Solenoid inlet valve with manual overrride.

This type of valve is maybe one of the handiest setups for a coffee machine, but not the cheapest. This valve is made up out of 2 systems. For the automatic boiler filling the solenoid valve is used. But if there is something wrong with the solenoid valve or level regulator you would always be able to fill the boiler manually with the manual valve. You would see these types of setups on coffee machine brands such as Astoria, Wega, Faema, Cimbali, Vibiemme and so on. But nowadays they are not that common anymore.

Solenoid inlet valve

This type of water inlet valve is currently one of the most common type of water inlet valves. In most cases this is just a solenoid valve installed in combination with a one way valve. In some cases you would have a casting, for example with Casadio and Cimbali, where the solenoid valve is combined with a valve. This has the disadvantage that these valves are more expensive. The "standard" 2 way solenoid valves are a lot cheaper.