Bunn SmartWAVE - Machine Function and Operations; Main Control Board; Filling System; Heating System

Bunn-O-Matic Corporation
13
Machine Function and Operations
Main Control Board
The main control is the brain of the brewer. In a digital brewer, the control board is the single
component that contains all of the programming software, it interprets all the data it receives
fromthelevelandtemperaturesensorsandactivatescomponentstofulllthosedemands.
The main control board responds to the users input through the membrane switch or mechan-
ical switches and activates and controls the brew cycle.
Filling System
Thellsystemmaintainsthelevelofwaterinthebrewer’stank.Anytimewaterisdrawnoff
ofthetankduringabrewcycleorfromthehotwateroutlet,thellcircuitactivatestorellthe
tank.
Thellsystemconsistsof:
• 120VACsolenoidinletvalveassembly(includesthestrainerandowregulator
• Fillprobe
Water enters the brewer through the water supply line and enters the chassis through a
strainerassembly;thisstrainercontainsanemeshscreentokeepanylargeparticles
fromenteringtheinletvalve.Fromthestrainerthewaterowsthroughthe0.222ow
control device and into the inlet solenoid.
The 120VAC solenoid inlet valve is activated by the control board anytime the
brewercallsforwater.Thevalveopensandallowswatertoow,underline
pressure,tothebottomofthetankwherethesilicontubeconnectstothell
tube.
The control board monitors the level of water in the tank through a low voltage
level probe mounted to the top of the tank. The control board grounds a 2.5VAC
signal to the tank through the water. If it looses this signal, the control board will
activate the inlet valve.
Heating System
Theheatingsystemconsistsof:
• Watertank
• Heatingelements
• High-limitthermostat
• Temperaturesensor
The heating circuit maintains the water in the tank at a preset temper-
ature this ensures that the water is always ready for brewing.
Water for brewing is contained in a 155 oz. stainless steel tank. This
tank contains a 1320W heating element (1850W in the high voltage
machine) that is powered by the line voltage into the machine. The
heating element is controlled by the control board through a relay
mounted on the board. There is a limit thermostat wired in series with
the element that will interrupt the circuit if the water in the tank over-
heats. This limit will open the circuit at 230°F and automatically resets
at 170°F.
The control board monitors the water in the tank by a temperature sensor that is in contact with the water. This
temperaturesensorisadigitalthermistor;thecontrolboardreadsthetemperatureasvalueofresistance.The
temperature sensor allows the control board to activate the heating element when the temperature drops below its
programmed value and shut down the element when the water temperature reaches the programmed holding value.