Bunn Axiom Series Installation guide

BUNN®TECHNICAL TRAINING
AXIOM®

Index
Unit 1: Installation
Site Requirements .............................................................................................................. 4
Location of the Serial Number .......................................................................................... 4
Install Preparation .............................................................................................................. 4
Water Supply Install ...........................................................................................................4
Electrical Install ..................................................................................................................5
Initial Start-Up ..................................................................................................................... 5
Unit 2: Setup
User Interface (Programming)........................................................................................... 7
Programming Lockout ....................................................................................................... 7
Programming Menus.......................................................................................................... 8
Level 1 Programming (BrewWIZARD®) ...................................................................... 8
Level 2 Programming ..................................................................................................8
Level 3 Programming ..................................................................................................10
Machine Setup ....................................................................................................................10
Brew Oz.........................................................................................................................10
Calibrating Flow Rate ..................................................................................................11
Enable BrewLOGIC®..................................................................................................... 11
Calibrate Temperature Probe ...................................................................................... 12
Setting Lime Adjustment............................................................................................. 12
  ResettingRellThreshold........................................................................................... 13
Unit 3: Machine Composition
Exterior Overview ............................................................................................................... 15
Product Outlets and Removable Parts ......................................................................15
User Interface (Operating)...........................................................................................15
Accessing the Inside of the Brewer.................................................................................. 16
Machine Function and Operations.................................................................................... 16
Main Control Board......................................................................................................16
Filling System...............................................................................................................16
Heating System ............................................................................................................ 17
Dispensing System ...................................................................................................... 18
Unit 4: Preventive Maintenance
Preventive Maintenance..................................................................................................... 20
PM Steps .............................................................................................................................20
Unit 5: Troubleshooting
Service Tools ...................................................................................................................... 23
Test Outputs ................................................................................................................. 23
Test Switches ............................................................................................................... 24
Service Fault Messages ..................................................................................................... 24
Troubleshooting Components .......................................................................................... 25
 TroublehsootingRell,Heating&BrewingSystems...................................................... 28
Triac Map ............................................................................................................................. 30
Schematics.......................................................................................................................... 31
Additional Resources......................................................................................................... 34
© 2011 Bunn-O-Matic Corporation. All Rights Reserved
Rev. B

Unit Objectives
Unit 1 installation
Given a realistic scenario depicting a new site install, the learner will be able to install and setup the brewer
for customer turnover without error.
Given a new machine, all the necessary tools and safety equipment, the learner will be able to install
the brewer without error.
The learner will be able to verify that the site requirements have been met.
The learner will be able to locate and document the serial number.
The learner will be able to hook up the water supply.
The learner will be able to hook up the electrical supply.
The learner will be able to power on the machine.

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Installation
Site Requirements
Space
• Counter able to support the weight of the equipment
• AXIOM® (2 top warmers) approx. dimensions (H 18.9 x W 8.5 x D 17.7)
• AXIOM® (3 lower warmers) approx. dimensions (H 16.8 x W 16.5 x D 17.7)
• AXIOM® (4/2 Twin) approx. dimensions (H 19.1 x W 16.4 x D 17.7)
• AXIOM® (0/6 Twin) approx. dimensions (H 20.5 x W 30.3 x D 17.7)
Plumbing
• AXIOM®(Single)1/4”arewaterconnection
• AXIOM®(Twin)3/8”arewaterconnection
• A shut-off valve should be installed in the line before the machine
• Connected to cold water
• Dynamic water pressure 20-90psi, set to 50psi if regulator is needed
Electrical
• 120VAC with a dedicated 20 amp circuit with proper breaker and receptacle
• 120/208-240VAC with a dedicated 20 amp circuit with proper breaker and receptacle 3
wire + ground (neutral, L1, L2, ground)
Location of the Serial Number
The machine’s serial number is located on the data plate which is attached
to the bottom of the front panel. The serial number begins with the letters AX.
The complete serial number will need to be documented on all work orders
and warranty tags.
Install Preparation
Step 1: Determine the electrical availability at site.
Step 2: Using a volt meter check voltage and color coding for each conductor on wall outlet.
Step 3: Factory installed power cord is 120VAC 15 amp. Unless ordered as 208-240VAC.
Step 4: If 208-240VAC power is used remove front panel and locate the main terminal block. Remove the 120VAC
power cord.
Step 5: Feed new power cord thru the rear of the machine.
Step 6:Installleadstothemaineldwiringterminalblock.
Step 7: Select desired voltage to be used by moving the selector switch. Switch is located in the upper most area of
the front of the brewer with the front panel removed.
Step 8:PlacetheAXIOMonasolidatsurfaceinsuringitislevelfronttorearandsidetosideusingalevel,adjust
legs as needed.
Water Supply Install
Step 1: Check dynamic water pressure, install a pressure regulator and set to 50 psi for pressures exceeding 90 psi
 orifexcessivepressureuctuations.
Step 2:Flushwaterlinesandlterifused
Step 3: Install shut-off valve.
Step 4:Attachthewaterlinetothearettingofthemachine.
Step 5: Turn on water and check for leaks.

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Electrical Install
Anelectricianmustprovideelectricalserviceasspeciedinconformancewithalllocal,state,andfederalelectrical
codes.
Step 1: Plug the unit into the power source.
Initial Start-Up
Step 1. Insert an empty funnel into the funnel rails.
Step 2. Place an empty server under the funnel.
Step 3. Connect the brewer to the power source.
Step 4. Turn master on/off switch to the on position, located on the side or rear of the machine if equipped.
Step5.PressandreleasetheBrewOn/OffSwitch.Waterwillowintothetankandstopwhenthetankislledtoits
 capacity.Displaywillshow“PLEASEWAIT...TANKFILLING”untiltankislledwithwater.
Step 6. Wait approximately twenty minutes for the water in the tank to heat to the proper temperature. Display will
show “READY TO BREW...WATER TEMP: 200°” when tank is at operating temperature. Some water
will drip from the funnel during this time; this is due to expansion and should not occur thereafter.
Step 7. Place a small container beneath the faucet and open the faucet handle. Release it when you hear the tank
 relling.
Step8.Watervolumesandowsettingshavebeenpresetatthefactory.RefertoadjustmentsfortheSetBrew
Ounces section of this manual should the volume need to be increased or decreased.
Step 9. The brewer is now ready for user setup.
Step 10. Repeat steps 5-9 for remaining side on Twins.
-1000 213.8 101.0 200 93.3
-500 212.9 100.5 200 93.3
0 212.0 100.0 200 93.3
500 211.1 99.5 200 93.3
1000 210.2 99.0 200 93.3
1500 209.3 98.5 200 93.3
2000 208.4 98.0 200 93.3
2500 207.4 97.4 200 93.3
3000 206.5 96.9 199 92.8
3500 205.6 96.4 198 92.2
4000 204.7 95.9 197 91.7
4500 203.8 95.4 196 91.1
5000 202.9 94.9 195 90.6
5500 201.9 94.4 195 90.6
6000 201.0 93.9 194 90.0
6500 200.1 93.4 193 89.4
7000 199.2 92.9 192 88.9
7500 198.3 92.4 191 88.3
8000 197.4 91.9 190 87.8
8500 196.5 91.4 189 87.2
9000 195.5 90.8 188 86.7
9500 194.6 90.3 187 86.1
10000 193.7 89.8 186 85.6
Brew water temperature is factory set at 200°F (93.3°C)
Areas of high altitude will require lowering this temper
a
ture to prevent boiling. This chart should be used as a
guide when readjusting the brew water temperature.
Altitude
(Feet)
Boiling point
of water
F C
Recommended
water temperature
F C
Brew water temperature is factory set at 200°F (93.3°C).
Areas of high altitude will require lowering this temperature
to prevent boiling. This chart should be used as a guide when
re-adjusting the brew water temperature.

Unit Objectives
Unit 2 setup
Given a realistic scenario depicting a new site install, the learner will be able to install and setup the brewer
for customer turnover without error.
Given an installed machine, all the necessary tools and safety equipment, the learner will be able to
set the machine up for initial operation.
The learner will be able to enter programming.
The learner will be able set the appropriate brew ounces.
  Thelearnerwillbeabletocalibratethesprayheadowrate.
The learner will be able to enable BrewLOGIC®and explain when it may be necessary.

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Setup and Programming
As with all BUNN®digital brewers the equipment has been designed for ease of use for both the end user as well as
service technicians alike. End users have an opportunity to see the status of the equipment during idle time or during
a brew cycle. It is technician friendly, as with any LCD display equipment BUNN®manufactures, allowing for step by
step calibrations, diagnostic functions as well as quick adjustments to name a few. The AXIOM™ has gone one step
beyond,byprovidingcuttingedgetechnologybymonitoringoutowratesofwaterexitingthebrewtankthereforeal-
lowing the control board the opportunity to adjust pot levels by increasing or decreasing the brew time needed during
a brew cycle. Resulting in perfect pot levels every time.
User Interface (Programming)
Display: The display shows the various functions.
Right Hidden Button: This is used to access the program mode and is also used to step forward through the menu.
Left Hidden Button: This is used to step backwards through the function list.
Digital (lower left under the display): This is used to select options that appear on the display during programming.
Brewer (center under the display): This is used to select options that appear on the display during programming.
Control (lower right under the display): This is used to select options that appear on the display during programming.
Programming Lockout
If the programming cannot be accessed, then the programming lockout switch is in the
Disable position. The switch is located on the control board. Remove the top panel,
locate the switch and place it into the Enable position.
REAR
FRONT
WARMERS
BUNN
®
WARMER
™
Control
LCD Display Right Hidden Button
Left Hidden Button
Digital Brewer

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Programming Menus
The programming menus for the AXIOM®are divided into three levels. Level 1, (BrewWIZARD®), allows for basic
brewing adjustments. Level 2 is used for more advanced brewing adjustments in addition to supporting service and
diagnosticfunctions.Thenallevelofprogramming,Level3,iswhereyoucanndadvancedscreenssuchas;Cal
Temperature, Lime Adjust, and Calibrate LP1-LP2.
While in programming you may exit and save any changes you have made by pressing and releasing the Enable On/
Off switch located on the front panel.
Level 1 Programming (BrewWIZARD®)
Press and hold the right hidden switch until the screen reads Brew Lockout? to enter programming.
This function will lockout an operator if a predetermined temperature has not been
achieved message will read “Brew temp to low please wait heating”.
This function allows the operator to adjust the brew volumes for the various sizes of
holding vessels.
This function allows the operator to adjust the brew strength/extraction time setting 1 is
non pulse setting, 14 being the highest setting using pulse brew.
This screen allows the operator to utilize the screen for advertising; a tag card can be
programmed with a message.
This function allows the operator to enter in a telephone number to call if service is
needed. This number will be displayed anytime a fault message appears.
This display is a prompt to advise you that you are exiting Level 1 programming.
Level 2 Programming
Level 2 programming can only be accessed by scrolling through Level 1 programming.
This function allows the operator to enter a 3 digit code to password protect Level 2
programming.
This function allows the operator to set a 3 digit code to password protect Level 2
programming.
This function allows the operator to choose between English, Spanish and French.
This function allows the operator to choose between English or Metric.
BREW LOCKOUT ?
NO YESDONE
BREW OZ: 64.0
(-) (+)DONE
BREW METER 3
- +
ENABLE ADS ?
NO YESDONE
ENTER SERVICE # ?
NO YES
EXITING
BrewWIZARD
ENTER PASSWORD
0 00
SET PASSWORD
0 00
SET LANGUAGE
NO YES
UNITS
METRIC ENGDONE

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Adjust the target temp of the Brew tank. Range of 185°F to 205°F.
This function sets the minimum temperature to start a brew cycle (BREW LOCKOUT).
Range of 2°F min. to 20°F max. below the Set Temp.
This display allows an optional asset number or tracking number to be assigned.
This function allows the sprayhead to “pulse on and off” during the brew cycle.
This function will adjust the amount of time the display will read “Dripping” after a brew
cycle is completed.
This display allows for a cleaning alert to be displayed (range of 1 to 30 days).
This function allows the tank heater(s) to run at a reduced rate during idle time.
This function allows a “Freshness Alert” message to display when a pre determined time
has elapsed from the last brew. Range 0.5 – 4.0 hrs.
This function allow for auto warmer turn off after a pre determined time has been
entered. Range 15 mins. To 6.0 hours.
    Thisfunctionadjustssensitivityoftherellcircuit.
This function allows the brewer to be calibrated in high lime locations and compensate
automatically as deposits build up in the equipment.
    Thisisusedtotelltheinternalcontrollerhowfastthewaterisowing.
This function provides a 60 second test mode to capture water from the sprayhead. This
measurement will then give you the numbers to enter into the “SPRAY OZ/M: xx” screen
above. Will not display when BrewLOGIC®is enabled.
Tracks the total number of brew cycles completed.
SET TEMP 200
O
(-) (+)DONE
SET READY 195
O
(-) (+)DONE
ENTER ASSET # ?
NO YES
SET PULSE BREW ?
NO YES
DRIP TIME 0:30
(-) (+)DONE
ENABLE CLEAN
NO YESDONE
Enabl Energy Savr
NO YESDONE
Enable Fresh Timer
NO YESDONE
ENABL WARMER OFF
NO YESDONE
XXX REFILL 155
(-) (+)DONE
ENABLE BrewLOGIC
NO YESDONE
SPRAY OZ/M: 25.0
(-) (+)DONE
CALIBRATE FLOW ?
NO YES
BREW COUNTERS ?
NO YES

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Allows the testing of individual components and the ability to check the membrane
switches for proper function.
Reset all of the previously entered brew settings, ad message, calibrations, etc.
Level 3 Programming
To access Level 3 programming press and hold the right hidden button, until the screen reads Cal. Temperature,
while on the Enter Password screen in Level 2 of programming.
This function allows the operator to “recalibrate” the CPU to the temperature thermistor.
This must be preformed when you replace a CPU or a thermistor.
This function allows for automatic adjustment of brew cycle times based on the output of
the sprayhead.
This function is used for calibration of the water volumes from the long level probe to the
short level probe.
    Thisisusedtotelltheinternalcontrollerhowfastthewaterisowing.
This function provides a 60 second test mode to capture water from the sprayhead. This
measurement will then give you the numbers to enter into the “SPRAY OZ/M: xx” screen
above. Will not display when BrewLOGIC®is enabled.
Machine Setup
Brew Oz.
It is necessary to setup the desired Brew Oz., due to the different size containers available in the market.
To convert liters to ounces use this simple math equation.
Liters X 33.9 = ounces
For example if you were using a 3.0L airpot this is what your equation would look like.
3.0 X 33.9= 101.7 rounded up to 102 uid US ounces.
Step 1: Enter programming Level 1, (BrewWIZARD®).
Step 2: Scroll to the Brew Oz. screen.
Step 3: Use the (-) or (+) to enter Oz. the desired ounces for the container to be used.
SERVICE TOOLS ?
NO YES
FACTORY DEFAULTS
NO YES
CAL TEMPERATURE
NO YESSENSOR?
% Lime Adjust OFF
(-) (+)DONE
LP1 LP2 OZ 4.50
(-) (+)DONE
SPRAY OZ/M: 25.0
(-) (+)DONE
CALIBRATE FLOW ?
NO YES
BREW OZ: 64.0
(-) (+)DONE

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Calibrating Flow Rate
Priortoprogrammingthemachineorbrewinganycoffeeaowratecalibrationmustbedone.Flowrateswillvary
from machine to machine, location to location, even from one end of a building to another.
Step 1: Enter Level 2 programming.
Step 2: Scroll to the Calibrate Flow screen. This test is used to capture water from the sprayhead during a pre-deter-
mined 60 second dispense valve cycle.
Step 3: Ensure the sprayhead and funnel are in place and put a container, measuring pitcher or server, underneath
the funnel, select Yes.
Step 4:Toactivatetheowratecheck,presstheBrewbutton.
Step 5: The valve will open for 60 seconds. Once all of the water has dripped out, use the (-) or (+) buttons to input
the volume collected and select Done.
It is very important to be accurate when performing this test as it will control the pot level during normal operation.
Enable BrewLOGIC®(Optional)
BrewLOGIC®isasystemthatmonitorsoutputofwaterowfromthetank.Thiscanbehelpfulwhentheequipment
isplacedinahighlimeenvironment.Astheowratebeginstoslowthesystemwillcompensatebyincreasingbrew
times as needed to maintain the proper pot levels. If enabled, the Calibrate Flow screen will not be visible.
Step 1:Ensurethebrewerisinit’snallocationandislevel.
Step 2: Enter Level 2 programming.
Step 3: Scroll to Enable BrewLOGIC®and select Yes.
Step 4: On the Calibrate Now? screen select Yes.
Step 5: The display will now read Too Hot-Will Cool Tank Now, the change to Press Brew When Ready, (with brew
funnel and container in place). The tank temperature must be in this range 130ºF to 170ºF, to perform the calibration.
Step 6: The display will read Cooling Tank Please Wait. Once the tank temperature is within the acceptable range
the display will read, Container Ready?. Place an empty container beneath the funnel and select Yes.
CALIBRATE FLOW ?
NO YES
CONTAINER RDY ?
QUIT YES
ENTER OZ: 24.5
(-) (+)DONE
ENABLE BrewLOGIC
NO YESDONE
CALIBRATE NOW ?
NO YES
TOO HOT - WILL
COOL TANK NOW
CONTAINER RDY ?
QUIT YES

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Step 7: The display will read Calibrate Spray, press brew start the calibration.
Step 8: WaitingTilCycle 4 the display will indicate cycles complete.
Step 9:UsetheDigital(-)switchandControl(+)switchtoadjusttotalvolumecaptured.PressDonewhennished.
Lime Adjustment
The “% Lime Adjust” menu is an adjustable percentage that you can modify to allow for
limecompensation(ow-rate)whenBrewLOGICisenabled.The“%LimeAdjust”menu
can be found in level 3 programming. The default value for Lime Adjust is set at 10%.
Smaller Percentage - lesstolerantofthesprayheadow-ratebeforecompensationofbrewtime.
Higher Percentage-moretolerantofthesprayheadow-ratebeforecompensationofbrewtime.
To Access and Modify the Lime Adjust:
1. Enter level 2 programming by depressing the right hidden button for 5 seconds. This display screen should read
“Enter Password”.
2. Press and release the right hidden switch until the display screen reads “Enter Password”.
3. Press and hold the right hidden switch until the display screen reads “Calibrate Temp Sensor?”. Once this occurs,
you have reached level 3 programming.
4. Press and release the right hidden switch until the display screen reads “% Lime Adjust”.
5. Use the Digital ( - ), Brewer (Done), and Control (+) switches to make adjustments to this setting.
Calibrating the Temperature Sensing Probe
Note: Calibrating the temperature sensing probe (thermistor) should be done when replacing the CBA or thermistor.
Allow the tank to heat the water to the ready temperature. No tests should be taken while the tank is heating as the
tank temperature must be stable before any readings are recorded.
Step 1: Remove the top panel of the machine.
Step 2: Gain access to the water in the tank, the thermistor grommet can be removed (keep the thermistor in contact
with the water.)
Step 3: Place the probe of a digital thermometer into the water and measure the temperature.
Step 4: Verify and record the temperature of the water.
Step 5: Access level 3 programming and navigate to “Cal Temperature Sensor?” menu
screen. Select Yes.
Step 6: Use the Digital (-) and Control (+) switches to enter the temperature that you
recorded from the digital thermometer reading.
CALIBRATE SPRAY
PRESS BREW START
WaitingTilCycle4
CYCLE 1 COMPLETE
ENTER OZ: 24.5
(-) (+)DONE
CAL TEMPERATURE
NO YESSENSOR?
% LimeAdjust ON
DONE
( - ) ( + )
Spray OZ/M: XX.X
LP1-LP2 OZ XX.X

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SettingtheRellThreshold
Therellsettinginprogrammingisaconductivitybasedsystem.Itisareadingthatisgeneratedbytheliquidlevel
probeandtheconductivityofthewaterinthetankhasatotalrangeof0-255(thiscanbeviewedontheRellpro-
gram screen). The lower the reading, the more conductance is being sensed. Conversely, the higher the reading, the
less conductance. Theoretically it would read 0 when the probe touches the water, and 255 when it is not touching
the water. However, due to water conditions and conditions in the tank, it may not have these exact readings.
The programmable portion of the system is the “switching point” (or threshold). This is typically set to 155 (your
default value). When the probe reading is less than this programmed number, it will be viewed as not requiring water
fromtherellsystem.Whenitisthenumberorgreater,itwillbeviewedasneedingwater.
If this threshold is causing problems, there’s a simple way to determine the optimum switching point.
Step 1:Withwaterknowntobetouchingtheliquidlevelprobe,recordtheprobereadingthatispresentontheRell
program screen (it will show the programmed threshold and the actual reading, here we want the actual
reading).
Step 2: Now create a situation where it is known the water is not touching the probe (can raise the probe out of the
tank). Record the probe reading.
Step 3: With the 2 readings, set the programmed threshold to be exactly half-way
between the 2 numbers.
XXX REFILL 155
(-) (+)DONE
Actual Reading Default Reading

Unit Objectives
Unit 3 Machine coMposition
Given a realistic scenario in which the learner has access to the machine’s internal components the learner
will understand the composition and functions of the brewer.
Given a realistic scenario requiring the learner to access the internal components of the machine the
learner will be able to remove the front panel and top cover.
The learner will disconnect the electrical and water supply.
The learner will remove the front panel and top cover.
Given an operating machine the learner will be able to give a general explanation of how the unit
operates.
The learner will be able to identify the functions of the main control board and identify the
components that correspond to each triac.
  Thelearnerwillbeabletoidentifythecomponentsandfunctionsofthellingsystem.
The learner will be able to identify the components and functions of the heating system.
The learner will be able to identify the components and functions of the dispensing system.
The learner will be able to identify the components and functions of the coffee holding system.

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Machine Composition
Exterior Overview
Product Outlets and Removable Parts
• Faucet assembly
• Sprayhead
• Funnel
• Server
User Interface (Operating)
The user interface on the AXIOM®consists of a mem-
brane switch adhered to the front of the brewer. The
membrane is connected to the main control board by a
ribbon cable. This membrane allows the user to select
a brew cycle in addition to control the warmer plates
depending on model type.
The display is also located in the front of the machine it is mounted to the main board. By showing what the status of
the machine the display aids the operator and technicians.
Enable Brew On/Off Switch: Pressing the “Enable Brew On/Off” switch (indicator on) supplies power to the brew
stationwarmer,enablesthebrewcircuit,andenergizesthetankrellcircuit.Pressingtheswitchagain(indicatoroff)
stopstankrellingandbrewingandde-energizesthebrewstationwarmer.Stoppingabrewcycleafterithasbeen
startedwillnotstoptheowofwaterintotheserveruntilthebrewfunnelisempty.
Note: Hot water will be available at the faucet in a limited amount when the “Enable Brew On/Off” switch is in
the“Off”positionbecausethetankwillnotrell.
Brew Switch: Momentarily pressing and releasing the switch starts a brew cycle when the “Enable Brew On/Off”
indicator is on.
Warmer Switches: Pressing any additional warmer switch so that the indicator is on, supplies power to the associ-
ated warmer. Note: APS and TC models have no warmers.
REAR
FRONT
WARMERS
BUNN
®
WARMER
™
Brew Switch
Enable Brew
On/Off Switch
Warmer Switches
Faucet
Funnel
Server
Sprayhead

AXIOM®Training Manual
16
Accessing the Inside of the Brewer
The majority of service work done on the AXIOM®brewer will require the service technician to access the inside of
the unit. The brewer has two removable panels, the top panel and front panel. Depending on the service required
one or both of these panels may need to be removed.
To work safely the power should disconnected prior to removing the panels. Once removed the brewer may be re-
connected to troubleshoot the machine.
Top Panel: The top panel is secured by one screw, to remove the panel remove the screw and while lifting the top
slightly from the front push lightly towards the rear you can then completely remove.
Front Panel: To remove the front panel, move the server and brew basket and set aside. Remove the four screws
holding the front panel on and slide panel out.
Machine Function and Operations
Main Control Board
The main control board is the brain of the brewer. In the
digital AXIOM®series brewer the control board is the single
component that contains all of the programming software, it
interprets all data it receives from the level and temperature
sensors and opens or closes various components to com-
plete a brew cycle.
In a digital brewer the main control board takes the place
of the liquid level board, timer board, and the mechanical
thermostat.
Filling System
Thellcircuitconsistsof
• 120VAC inlet solenoid
• 2 Fill probes (referred to as Short LP1 and Long LP2)
Thellsystemmaintainsthelevelofwaterinbrewtank.
Anytimewaterisdrawnfromthetankthellcircuitacti-
vatestorellthetank.
Water enters the brewer through the water supply line it
then enters the chassis thru a copper line that is attached
to the inlet solenoid. When the water enters the inlet
valveitmustrstowpastanemeshscreenhoused
within the valve, this mesh screen is designed to keep
large particles of foreign material from entering the valve.
The 120VAC inlet solenoid is activated by the control board anytime the brewer calls for water. The inlet solenoid is
energizedtoallowwatertoowunderlinepressure.Itthenentersthetankthroughasiliconehoseattachedatthe
base of the tank.
Inlet Solenoid
Fill Tube
Copper Line
Flow Control Body
Flow Control Washer
Strainer
Inlet Solenoid
Transformer
Tank Heater Relay

Bunn-O-Matic Corporation
17
The control board monitors the level of water in the tank through a
low voltage level probe (LP2 Probe) mounted to the top of the tank.
When water touches the LP2 probe, the control board grounds a low
voltage AC signal to the tank through minerals in the water and the
inlet solenoid is de-engergized. A relay on the CBA closes it’s contacts
to complete the heating circuit and the heating element(s) will now
receive voltage in order to heat the water in the tank. When the CBA
detects water has reached ready temperature with the use of a therm-
istor,thetankwilllltoLP1probelevel.Theheatingcircuitwillremain
closed until water reaches the set tank temperature.
Heating System
The heating system consists of:
• Water tank
• Heating elements
• Triacs
• Temperature Sensor
• Blanket Warmer
The heating circuit maintains the water in the tank at a preset tempera-
ture; this insures the water is always ready for brewing. Water for brew-
ing is contained in a 200 oz. Stainless steel tank. This tank contains 2
heating elements that are powered by the incoming line voltage to the
machine. Both heating elements are controlled by a relay mounted on
the main control board. The high limit thermostat is located inside the top
cover on the front of the tank, the limit thermostat will interrupt the heat-
ing circuit should the tank overheat.
The control board monitors the water temperature with the use of a
thermistor that is in contact with the water. When water in the tank drops
below the ready temperature, the control board interprets the value of the
thermistor and in return will activate the heater relay to bring the tank
temperature back up to the set tank temperature.
The blanket warmer provides a low consistent heat around the tank at
the point of the temperature sensor. This additional heat aids the heater
circuit by reducing the number of on/off cycles, thereby extending the life
of the relay contacts and the heater.
LP 2 LP 1
Thermistor
LP1 Probe
LP2 Probe
2268W
Heating Element
(Dual Volt Models)
1425W
Heating Element
1425 Watt Blanket Heater High Limit
Thermostat

AXIOM®Training Manual
18
Dispensing System
The dispensing system consists of:
• Brew valve
• Sprayhead
The dispensing system is what makes the brewer a coffee brewer. It dispenses the hot water over a bed of coffee
grounds to create the product.
The AXIOM®usesagravitydumpvalvesystem.Duringthebrewcyclethebrewvalveopensallowingwatertoow
from the tank and out the Sprayhead. The control board opens and closes this valve according to perimeters pro-
grammedintothecontrolboardbasedonaspecicrecipe.
While the dispensing system works much the same way as any other BUNN®gravity feed brewer. One major differ-
ence can be found that’s cutting edge technology to combat lime scale buildup within the hydraulic system.
BrewLOGIC®utilizes2liquidlevelprobes,asdiscussedearlierthelong(LP2)probeperformsthestandardtankll
when the control board calls for water. When BrewLOGIC®is activated and calibrated as earlier discussed the tank
waterismonitoredfor“owrate”outofthesprayheadusingamathematicalalgorithmthatwasdeterminedduring
calibration.Iftheowratefromthesprayheadistooslowortoofastwithinthersttwocycles,thecontrolboardwill
adjust the overall brew “time” to compensate.
Dispense Solenoid
Dispense Solenoid
Hot Water Faucet
Sprayhead

Unit Objectives
Unit 4 preventive Maintenance
Given a realistic scenario depicting a machine requiring a preventive maintenance, the learner will be able to
identify which elements of a component need to be serviced without error.
Given a machine, all the necessary tools and safety equipment, the learner will be able to identify the
components that need to be serviced for the PM.

AXIOM®Training Manual
20
Preventive Maintenance
In order to maintain proper operation and long service life BUNN®recommends performing the preventive main-
tenance every 6 months. Individual customers will vary with some customers choosing not to receive preventive
maintenance.
Tools Required:
• 2 Flat head screwdrivers (1 small, 1 medium)
• Adjustable wrench
• Needle nose pliers
• Deliming tool (BUNN P/N: 38227.0000)
Prior to servicing the brewer:
• Disconnect the electrical supply
• Shut off water supply
PM Steps
Step 1: Remove probes from tank lid.
□Remove top and front access panels
□Drain tank using drain hose located behind front panel. Caution Hot Water!!
□Remove thermistor probe (temp probe) from the top of the tank. Clean and inspect
□Remove liquid level probes (2) from tank lid clean and inspect
□Reassembly is the opposite of disassembly
Step2:Rebuildbrewvalve,cleanoutletttingsattank.
□Remove wire leads from brew valve
□Carefully remove silicon hose from brew valve
□Remove mounting nuts
□Remove 4 screws from valve
□Replace plunger, spring and rubber seat using rebuild kit, (BUNN P/N: 11517.0008)
□ Carefullyremovethesiliconhosesfromtheoutlettankttings
□ Cleanttingsusingdelimingtool(longend)orsuitabletool
□Reassembly is the opposite of disassembly
Step 3: Rebuild hot water faucet.
□Replace hot water seat cup by unscrewing the bonnet assembly
□Remove old seat cup
□Install new seat cup, (BUNN P/N: 02766.0000)
□Reassembly is opposite of disassembly
Step4:CleanandinspectSprayheadcleansprayheadtting.
□Clean and inspect Sprayhead
□ CleanSprayheadttingusingdelimingtool
Step 5: Inspect brew funnel for missing or loose parts.
Step 6: Inspect water connection points for signs of leakage.
Step 7: Inspect power cord.
Step 8: Return AXIOM®to service.
□Turn on water supply and check for leaks
□Plug AXIOM®in at wall receptacle
□ Allowtanktollandheattooperatingtemperature