Each group has a three-way solenoid valve mounted underneath each head to allow for water
flow through the group.
* Each valve consist of valve body, valve stem, spring-loaded
piston and a coil.
* The valve is mechanically closed by spring pressure.
* The coil receives electrical power when the brew switch or
keypad is depressed.
* When energized, the coil creates a magnetic field which opens
the piston, allowing water to flow through the valve body.
* When the valve closes, pressurized water from the valve outlet to
the diffuser block discharges through the bottom of the
valve stem to the drain box.
Flowmeters
The flowmeters measure the volume of water passing through to the
groups.
* The Flowmeter is made up of an electromagnetic field, an impeller
and a body.
* As water enters the Flowmeter body it causes the impeller to
rotate. The impeller has two small magnets imbedded in it.
As the impeller spins, the magnets pass the magnetic field,
causing a switch to close, which sends a pulse signal to the
microprocessor.
Autofill System
The autofill system maintains the water level in the steam boiler.
* The autofill system consists of an autofill circuit on the control box, an auto-fill probe and an
autofill valve.
* The autofill probe is a metal probe, which sticks down into the boiler. An electrical lead is at
tached to the top of the probe, approximately 1-2 vac travels through this probe from the
control box.
* As the water rises in the boiler, and reaches the probe, the 1-2 vac travels through the water
and grounds itself against the sidewall of the boiler. When this ground signal travels back
to the control box, it signals the auto-fill circuit to switch off the auto-fill valve.
* As water is depleted from the boiler it lowers below the probe causing the signal to be inter-
rupted. When the auto-fill circuit can no longer read a ground signal, it activates the
autofill valve allowing water to enter the boiler.
* The autofill valve consist of an electromagnetic coil and a valve.
* The valve is mechanically closed by spring tension. When the coil is energized it creates a
magnetic field, which pulls the valve piston open, allowing water to pass through it.
Ground Wire
Flowmeter Field
Magnets
Impellor
O-ring
Flowmeter Body
Valve Piston
Valve Body
Solenoid Coil
Brass Washer
Fitting for tube from
Flowmeter
Valve Shaft
Group Valves
