In many aircraft coffee makers, there is also a manual vent valve which must be opened to vent the brewing tank. After filling the brewing tank, the fill valve is turned off and the vent valve is closed.
The coffee maker is turned on, and the water begins to heat. While some of the coffee makers will send the heated water to a brew nozzle over a tray containing the coffee, which is located over the server, others have a hot water valve which may be used to divert the hot water to the side through a nozzle. This hot water valve diverts water to the nozzle for use in making hot tea.