Bunn U3 U3A User Manual

BUNN

®

U3

U3A

OPERATING & SERVICE MANUAL

BUNN-O-MATIC CORPORATION

POST OFFICE BOX 3227

SPRINGFIELD, ILLINOIS 62708-3227

PHONE: [phone] FAX: [phone]

10060.0000G 8/00 ©1984 Bunn-O-Matic Corporation

INTRODUCTION

This brewer will brew a three gallon batch of coffee into each reservoir (one at a time). Each reservoir has its
own dispensing faucet(s).The brewer also has a hot water faucet(s) for allied beverage use. It is only for indoor
use on a sturdy counter.

WARRANTY

Bunn-O-Matic Corp. (“Bunn”) warrants the equipment manufactured by it to be commercially free from defects
in material and workmanship existing at the time of manufacture and appearing within one year from the date of
installation. In addition:

1.) Bunn warrants electronic circuit and/or control boards to be commercially free from defects in material and

workmanship for two years from the date of installation.

2.) Bunn warrants the compressor on refrigeration equipment to be commercially free from defects in material

and workmanship for two years from the date of installation.

3.) Bunn warrants that the grinding burrs on coffee grinding equipment will grind coffee to meet original factory

screen sieve analysis for three years from date of installation or for 30,000 pounds of coffee, whichever comes first.

This warranty does not apply to any equipment, component or part that was not manufactured by Bunn or that,
in Bunn’s judgement, has been affected by misuse, neglect, alteration, improper installation or operation, improper
maintenance or repair, damage or casualty.

THE FOREGOING WARRANTY IS EXCLUSIVE AND IS IN LIEU OF ANY OTHER WARRANTY, WRITTEN OR
ORAL, EXPRESS OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, ANY IMPLIED WARRANTY OF EITHER
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. The agents, dealers or employees of Bunn are

not authorized to make modifications to this warranty or to make additional warranties that are binding on Bunn.
Accordingly, statements by such individuals, whether oral or written, do not constitute warranties and should not
be relied upon.

The Buyer shall give Bunn prompt notice of any claim to be made under this warranty by telephone at (217)
529-6601 or by writing to Post Office Box 3227, Springfield, Illinois, 62708-3227. If requested by Bunn, the Buyer
shall ship the defective equipment prepaid to an authorized Bunn service location. If Bunn determines, in its sole
discretion, that the equipment does not conform to the warranty, Bunn shall repair the equipment with no charge
for parts during the warranty period and no charge for labor by a Bunn Authorized Service Representative during
the warranty period. If Bunn determines that repair is not feasible, Bunn shall, at its sole option, replace the
equipment or refund the purchase price for the equipment.

THE BUYER’S REMEDY AGAINST BUNN FOR THE BREACH OF ANY OBLIGATION ARISING OUT OF THE SALE
OF THIS EQUIPMENT, WHETHER DERIVED FROM WARRANTY OR OTHERWISE, SHALL BE LIMITED, AS
SPECIFIED HEREIN, TO REPAIR OR, AT BUNN’S SOLE OPTION, REPLACEMENT OR REFUND.

In no event shall Bunn be liable for any other damage or loss, including, but not limited to, lost profits, lost sales,
loss of use of equipment, claims of Buyer’s customers, cost of capital, cost of down time, cost of substitute
equipment, facilities or services, or any other special, incidental or consequential damages.

Page 2

10060 031599

Page 3

ELECTRICAL REQUIREMENTS

CAUTION - The brewer must be disconnected from the power source until specified in

Initial Set-Up.

L2 RED

WHITE

NEUTRAL

L1 BLACK

120V A.C.

208 OR
240V A.C.

120V A.C.

P1841

U3 & U38 requires 3-wire, grounded service rated
120/208 or 120/240 volts ac, U3-30 amp,U38-40 amp,
single phase, 60 Hz. Proceed as follows:

L2 RED

230V A.C.

L2 RED

208V OR 240V

L3 BLUE

L1 BLACK

380V OR 440V

208V OR 240V
380V OR 440V

208V OR 240V
380V OR 440V

P1843

U333 & U3833 requires 3-wire, grounded service

rated 240 volt ac, 35 amp or 440 volts ac, 30 amp for
U333,three phase, 60 Hz or 380 volts ac, 30 amp for
U3833, three phase, 50 Hz. Proceed as follows:

L1, L2, L3, are the 3 phases

V1 = Phase to phase voltage,

between any 2 phases.

V2 = Phase to neutral voltage,

any phase to neutral.

L1 BLACK

P1844

SYSTEM
VOLTAGE V1 V2

208 208 120
240 240 139
380 380 220

P1842

U3A models require 2-wire, grounded service
rated 230 volts ac, 30 amp, single phase, 50 Hz.
Proceed as follows:

U3833 requires 4-wire, grounded service rated

380 volts ac or 440 volts ac, 30 amp, three phase, 50
Hz. Proceed as follows:

440 440 254

ELECTRICAL INSTALLATION INSTRUCTIONS
CAUTION – Improper electrical installation will damage electronic components.

1. An electrician must provide electrical service as specified.

2. Using a voltmeter, check the voltage and color coding of each conductor at the electrical source.

3. Before electrically connecting the brewer, remove the front cupola cover (some models have the thermostat knob

on the outside of the cover) and rotate the thermostat knob fully counterclockwise to the "OFF" position. Keep this

knob in the "OFF" position until performing the

Initial Setup

.

4. Electrical service is connected at the upper rear of the single service and scrambler brewers using a junction

box. On double service brewers the rear decorative channel must be removed for access to the terminal block.

5. Connect the brewer to the power source and verify the voltage at the terminal block before proceeding. Replace

all panels.

Page 4

10060 031599

ELECTRICAL INSTALLATION INSTRUCTIONS (CONT.)

6. If plumbing is to be hooked up later be sure the brewer is disconnected from the power source. If plumbing
has been hooked up, the brewer is ready for

Initial Setup

.

NOTE: Schematic wiring diagrams are included in this manual.

PLUMBING REQUIREMENTS

These brewers must be connected to a cold water system with operating pressure between 20 (138) and 90 psi
(620 kPa) from a 1/2" or larger supply line. A shut-off valve should be installed in the line before the brewer. Install
a regulator in the line when pressure is greater than 90 psi (620 kPa) to reduce it to 50 psi (345 kPa). The water
inlet fitting is 3/8" flare.

NOTE - Bunn-O-Matic recommends 3/8" copper tubing for installations from the 1/2" water supply line. A tight
coil of copper tubing in the water line will facilitate moving the brewer to clean the countertop. Bunn-O-Matic does
not recommend the use of a saddle valve to install the brewer. The size and shape of the hole made in the supply
line by this type of device may restrict water flow.

This equipment must be installed to comply with the Basic Plumbing Code of the Building
Officials and Code Administrators International, Inc. (BOCA) and the Food Service Sanitation
Manual of the Food and Drug Administration (FDA).

INITIAL SETUP

CAUTION - The brewer must be disconnected from the power source throughout the initial setup, except when

specified in the instructions.

IMPORTANT: Brewer must be level and installed on a sturdy structure.

Electrician's and Plumber's Instructions are provided. These instructions should be carefully
followed before proceeding with initial setup.

Be sure all electrical and plumbing connections are tight.

1. Open manual fill valve located on the bottom of the brewer. Water should start filling the tank. When water is
visible in the hot water gauge glass (center spigot), close valve. Approximate time for filling manually is 3
minutes.

CAUTION: Never leave brewer unattended while manually filling tank.

2. Connect the brewer to the power source. Turn "ON/OFF" switch to the "ON" position. Water should finish filling
tank automatically.

NOTE: It is recommended that the "ON/OFF" switch be left in the "OFF" position at the end of the operating day or
when unattended for a long period of time.

3. Disconnect the brewer from the power source. Remove front cupola cover for access to thermostat knob and
timer. On some brewers the thermostat knob is located on the front of the cupola cover.

4. Turn the thermostat knob clockwise to an approximate 5 o'clock position. Allow 1-1/2 hours for water to heat.
Time will vary with incoming water temperature.

5. On initial warm-up, some water may flow thru the overflow spigot due to expansion of the cold water in the
tank. This will not recur during the use of the brewer and may be avoided on the initial warm-up by drawing
off 1/2 gallon decanters of water each 15 minutes till brewing temperature is reached.

Page 5

10060 080900

INITIAL SETUP (cont.)

6. Brewing cycles may be started whenever water temperature is correct. This condition is indicated by the dial
thermometer on front of the brewer. Whenever the pointer is in the green, brewer is ready for brewing. The

°

recommended brewing temperature is approximately 200

F (93°C). Water temperature may be increased by

turning thermostat knob clockwise, decreased by turning knob counterclockwise.

7. When desired temperature is reached, insert funnel support, funnel and funnel cover in position. Be sure the
water swing spout is over the center of the funnel cover, turn "ON/OFF" switch to the "ON" position, push and
release "START" and run a brew cycle of hot water only. At the end of this cycle, brewer will be ready for checking
timer adjustment.

8. The timer has been preset for a 4 minute cycle. This setting will deliver approximately 3 gallons of water per
brewing cycle. To increase or decrease amount of water, adjust the timer as required. See

Adjusting Brew

Volumes.

9. Having determined final settings of the thermostat and the timer, replace front cupola cover. Brewer is now
ready for brewing coffee.

ADJUSTING BREW VOLUMES

CAUTION - Disconnect the power source from the brewer prior to the removal of any panel for the replacement

or adjustment of any component.
NOTE: Prior to setting or modifying batch sizes, check that the brewer is connected to water supply, the tank is
properly filled, and a funnel support, funnel and funnel cover are in place.

1. Modifying batch sizes. To modify a batch volume, first check that the SET/LOCK switch is in the “SET”
position on the circuit board.
To increase a batch size. Press and hold the START or BREW switch until you see three breaks in the water
stream from the swing arm. Release the switch (Failure to release the switch within two seconds after the
third break in the water stream causes the volume setting to be aborted and previous volume setting will
remain in memory) and press it again one or more times. Each time the switch is pressed, two seconds are
added to the brew time period. Allow the brew cycle to finish in order to verify that the desired volume has
been achieved.
To decrease a batch size. Press and release the START or BREW switch once for every two-second interval
to be removed from the total brew time period; then immediately press and hold down the START or BREW
switch until you see three breaks in the water stream from the swing arm. Release the switch. (Failure to
release the switch within two seconds after the third break in the water stream causes the volume setting to
be aborted and previous volume setting will remain in memory). Allow the brew cycle to finish in order to
verify that the desired volume has been achieved.

2. Setting batch sizes. To set a batch volume, first check that the SET/LOCK switch is in the “SET” position on
the circuit board. Press and hold the START or BREW switch until you see three breaks in the water stream
from the swing arm, and then release the switch. (Failure to release the switch within two seconds after the
third break in the water stream causes the volume setting to be aborted and previous volume setting will
remain in memory). View the level of the liquid being dispensed. When the desired level is reached, turn the
ON/OFF switch to “OFF” (lower). The brewer remembers this volume and will continue to brew batches of
this size until the volume setting procedure is repeated.

NOTE: When brewing coffee, batch volumes will decrease due to absorption by the coffee grounds.
NOTE: HALF-BATCH AND FULL BATCH SETTINGS MUST EACH BE SET SEPARATELY.

3. Setting programming disable feature. If it becomes necessary to prevent anyone from changing brew times
once programmed, you can set the SET/LOCK switch to the “LOCK” position. This will prevent any program­ming to be done until switch is once again placed in the “SET” position.

Page 6

10060 080900

COFFEE BREWING

1. Brewing cycles may be started whenever water temperature is correct. This condition is indicated by the dial

thermometer on front of the brewer. Whenever the pointer is in the green, brewer is ready for brewing.

2. Insert Bunn® filter in funnel and add desired amount of coffee.

3. Level the bed of coffee and place funnel into the funnel support. Place funnel cover over the funnel and be sure

the water swing spout is over the center of the funnel cover.

4. Turn "ON/OFF" switch to the "ON" position.

5. Push and release "START" switch to start the brew cycle.

6. Water swing spout should not be moved as long as water is flowing into the funnel cover. When water stops

flowing, it may then be moved for access to brewing funnel.

7. Remove funnel cover. Funnel should not be removed from brewer until drip out of coffee has been completed.

8. To empty funnel, invert it over a waste container to dispose of filter and grounds. An additional flange is

provided on the funnel to help make this step easier.

NOTE: Hot water may be drawn from the hot water faucet during a brew cycle. However, if a large amount of hot
water is drawn off (over 1 gallon) operator should wait to do so between brewing cycles.

CLEANING

NOTE: Tanks and tank components should be delimed regularly based on local water conditions. Excessive mineral

build-up on stainless steel surfaces can initiate corrosion reactions resulting in serious leaks.

1. Remove both funnels, funnel lids and supports, under hot water, rinse away all coffee oils. Wipe with a clean

damp cloth.

2. Drain both coffee reservoirs by opening coffee faucets. When empty, close faucets.

3. Cycle two or three inches of water into each coffee reservoir and scrub entire reservoir area.

4. Drain both coffee reservoirs and rinse. Use clean damp cloth to wipe both reservoirs.

5. Install both coffee funnel supports, funnels and funnel lids.

6. Remove the sight gauge cap, insert sight gauge cleaning brush into the sight gauge glass tube and clean.

7. To clean coffee faucets, remove the faucet handle from the faucet and faucet clean out cap. Clean faucet with

a faucet cleaning brush and wipe all parts with a damp cloth. Replace faucet seat cups periodically if badly
stained or to stop faucet dripping. DO NOT CLEAN THE HOT WATER FAUCET.

8 Reassemble the coffee faucets.

9. Wipe the entire outside surface of the machine with a clean damp cloth. Wipe dry.

FILTER HOLDER

1. A filter holder is supplied with each U3 coffee brewer. Its purpose is to keep the filters in their originally formed

shape to properly fit the brewer funnel.

2. It is suggested that only one cluster of filters be placed in the holder at one time for best results.

3. Not using the filter holder may permit the filters to gradually widen out towards a flat shape, especially so if

humidity is present. Once a filter has lost its upright side walls, it may tend to collapse inward when placed in
the brewing funnel. If this happens the hot water spray may cause one side to fall inwards, letting coffee
grounds flow over the edge of filter and into the brewed coffee. Proper use of the holder should prevent this
problem.

Page 7

10060 080900

TROUBLESHOOTING

A troubleshooting guide is provided to suggest probable causes and remedies for the most likely problems

encountered. If the problem remains after exhausting the troubleshooting steps, contact the Bunn-O-Matic
Technical Service Department.

• Inspection, testing, and repair of electrical equipment should be performed only by qualified service personnel.

• All electronic components have 120 volt ac and low voltage dc potential on their terminals. Shorting of

terminals or the application of external voltages may result in board failure.

• Intermittent operation of electronic circuit boards is unlikely. Board failure will normally be permanent. If an
intermittent condition is encountered, the cause will likely be a switch contact or a loose connection at a
terminal or crimp.

• Solenoid removal requires interrupting the water supply to the valve. Damage may result if solenoids are
energized for more than ten minutes without a supply of water.

• The use of two wrenches is recommended whenever plumbing fittings are tightened or loosened. This will help
to avoid twists and kinks in the tubing.

• Make certain that all plumbing connections are sealed and electrical connections tight and isolated.

• This brewer is heated at all times. Keep away from combustibles.

WARNING – • Exercise extreme caution when servicing electrical equipment.

• Unplug the brewer when servicing, except when electrical tests are specified.

• Follow recommended service procedures

• Replace all protective shields or safety notices

PROBLEM

Brew cycle will not start

PROBABLE CAUSE

1. No water

2. No power or incorrect voltage to
the brewer

REMEDY

Water lines and valves to the brewer
must be open.

(A1) Check the terminal block for
120 volts ac across the red and
white terminals and the black and
white terminal on three wire 102/
208 volt or 120/240 volt models.
(A2) Check the terminal block for
208 volts ac, 230 volts ac or 240
volts ac on "A Series" brewers across
the red and black terminals on two
wire single phase 208 volt, 230 volt
and 240 volt models.
(A3) Check the terminal block for
208 volts ac, 240 volts ac, 380 volts
ac across the black and blue termi­nals, the blue and red and the black
and red terminals on three wire three
phase 208 volt, 240 volt and 380 volt
models.

Page 8

10060 031500

TROUBLESHOOTING (cont.)

PROBLEM

Brew cycle will not start (cont)

PROBABLE CAUSE

2. No power or incorrect voltage to
the brewer (cont)

3. Water level below pump housing.
(Water level in the hot water gauge
glass should be approximately half
full).

4. ON/OFF Switch

REMEDY

(A4) Check the terminal block for
440 volts ac across the black and
blue terminals, black and red termi­nals and the red and blue terminals
on four wire three phase 440 volt
models.

(B) Check circuit breakers or fuses.

Be sure water shut-off valve is open
and that the in-line filters or strain­ers are not blocking water flow. (Do
not confuse water shut-off valve with
the manual fill and drain valve un­derneath the brewer).

Refer to

Service

- ON/OFF Switch for

testing. See page 22

5. Start Switch

6. Relay

7. Timer

8. Pump

9. Solenoid Valve

10. Strainer

Refer to

Service

- Start Switches for

testing procedures. See page 29

Refer to

Service

- Relay for testing

procedures. See page 24

Refer to

Service

- Timer for testing

procedures. See page 31 or 33

Refer to

Service

- Pump for testing

procedures. See page 23

Refer to

Service

- Solenoid Valve for

testing procedures. See page 27

(A) Direction of flow arrow must be
pointing towards brewer.

(B) Remove the strainer and check
for obstructions. Clear or replace.

Brew cycle starts with brew lockout
relay engaged.

1. Relay

Page 9

Refer to

Service

- Relay for testing

procedures. See page 24

10060 080900

TROUBLESHOOTING (cont.)

PROBLEM

Tank not filling

PROBABLE CAUSE

1.ON/OFF Switch (This switch
must be in the "ON" position for the
refill circuit to operate.

2. No water

3. Solenoid Valve

4. Probe

5. Liquid Level Board

REMEDY

Refer to

Service

- ON/OFF Switch
for testing procedures. See page
22

Be sure water shut-off is open and
that in-line filters or strainers are
not blocking water flow. (Do not
confuse water shut-off valve with
the manual fill and drain valve un­derneath brewer).

Refer to

Service

- Solenoid Valve
for testing procedures. See page
27

Refer to

Service

- Probe for testing

procedures. See page 20

Refer to

Service

- Liquid Level
Board for testing procedures. See
page 20

Water running out of the overflow

1.Brewer not level

2. Solenoid Valve

3. Liquid Level Board

4. Probe

5. Manual fill and drain valve un­derneath brewer open.

Brewer must be level and installed
on a sturdy structure.

Refer to

Service

- Solenoid Valve
for testing procedures. See page
27

Refer to

Service

-Liquid Level
Board for testing procedures. See
page 20

Refer to

Service

- Probe for test-

ing procedures. See page 20

Be sure valve is closed.

Page 10

10060 080900

TROUBLESHOOTING (cont.)

PROBLEM

Water not hot

Circuit breaker keeps tripping

PROBABLE CAUSE

1. Limit Thermostat
CAUTION - Do not eliminate or
bypass limit thermostat. Use only
Bunn-O-Matic replacement part
#29329.1000

2. Control Thermostat

3. Tank Heater(s)

4. Contactor

1. Circuit Breaker

REMEDY

Refer to

Service

- Limit Thermo­stat for testing procedures. See
page19

Refer to

Service

- Control Ther­mostat for testing procedures. See
page 17

Refer to

Service

- Tank Heater for

testing procedures. See page 30

Refer to

Service

- Contactor for

testing procedures. See page 15

Refer to

Service -

Circuit Breaker
for testing procedures. See page
14

Water keeps running from swing
spout

Inconsistent coffee yield

Funnels overflow

2. Tank Heater(s)

1. Timer

2. Start Switch

1. Timer

2. Solenoid Valve

3. Lime build-up in swing spout
and pump tubing.

1. Filters

Refer to

Service

- Tank Heater for

testing procedures. See page 30

Refer to

Service -

Timer for testing

procedures. See page 31 or 33

Refer to

Service -

Start Switch for

testing procedures. See page 29

Refer to

Service -

Timer for testing

procedures. See page 31 or 33

Refer to

Service -

Solenoid Valve
for testing procedures. See page
27

Remove swing spout and insert
deliming rod down into pump tub­ing as far as possible.

Use Bunn® filters made for the U3
brewer.

2. Hole in bottom of funnel ob­structed.

Page 11

Remove obstruction.

10060 080900

TROUBLESHOOTING (cont.)

PROBLEM

Funnels overflow (cont.)

Coffee reservoir overflows

PROBABLE CAUSE

3. Pump - Flow Rate

4. Soft Water

1. Coffee reservoir not completely
empty befor a brew cycle was
started.

2. Timer

REMEDY

Check pump flow rate with a watch.
Pump flow rate should be approxi­mately 24 ounces in 15 seconds.
Be sure pump assembly is free of
any obstructions.

When using a water softener, a
coarse grind of coffee may be pre­ferred. If required, a bypass sys­tem is available as an optional
feature.

Be sure coffee reservoir is empty
before brew cycle is started.

Refer to

Service

-Timer for test-

ing procedures. See page 31 or 33

Brewer is making unusal noises

3. Pump - Flow Rate

1. Solenoid Valve

2. Plumbing lines

3. Water supply

Check pump flow rate with a watch.
Pump flow rate should be approxi­mately 24 ounces in 15 seconds.
Be sure pump assembly is free of
any obstructions.

The nut on the solenoid must be
tight or it will vibrate during opera­tion.

Plumbing lines should not be rest­ing on the counter top.

(A) The brewer must be connected
to a cold water line.

(B) Water pressure to the brewer
must not exceed 90 psi (620 kPa).
Install a regulator if necessary to
lower the pressure to approxi­mately 50 psi (345 kPa).

4. Tank Heater(s)

Page 12

Remove and clean lime off the
tank heater. See page 30

10060 080900

SERVICE

This section provides procedures for testing and
replacing various major components used in this
brewer should service become necessary. Refer to

Troubleshooting

cause of any problem.

WARNING - Inspection, testing, and repair of electri­cal equipment should be performed only by qualified
service personnel. The brewer should be unplugged
when servicing, except when electrical tests are re­quired and the test procedure specifically states to
plug in the brewer.

COMPONENT ACCESS

WARNING - Disconnect the brewer from the power

source before the removal of any panel or the replace­ment of any component.

All components are accessible by the removal of
the swing spout, front cupola cover, rear cupola cover
and the cupola.

for assistance in determining the

Disconnect the swing spout nut from the swing
spout base fitting. Remove swing spout.

Remove the four #8-32 screws, two on the front and
rear, securing front and rear cupola covers to the
cupola.

Slip cupola off of the component bracket.

FIG. 1 COMPONENT ACCESS

Page 13