Bunn RT Owner's Manual

OT & RT

(S/N RT00005364 & up)

INSTALLATION & OPERATING GUIDE

BUNN-O-MATIC CORPORATION

POST OFFICE BOX 3227

SPRINGFIELD, ILLINOIS 62708-3227

PHONE: [phone] FAX: [phone]

To ensure you have the latest revision of the Operating Manual, or to view the Illustrated Parts
Catalog, Programming Manual, or Service Manual, please visit the Bunn-O-Matic website, at
www.bunn.com. This is absolutely FREE, and the quickest way to obtain the latest catalog and

manual updates. For Technical Service, contact Bunn-O-Matic Corporation at 1-800-286-6070.

32440.0000D 05/12 © 1999 BUNN-O-MATIC CORPORATION

BUNN-O-MATIC COMMERCIAL PRODUCT WARRANTY

Bunn-O-Matic Corp. (“BUNN”) warrants equipment manufactured by it as follows:

1) Airpots, thermal carafes, decanters, GPR servers, iced tea/coffee dispensers, MCP/MCA pod brewers thermal servers
and Thermofresh servers (mechanical and digital)- 1 year parts and 1 year labor.

2) All other equipment - 2 years parts and 1 year labor plus added warranties as specified below:
a) Electronic circuit and/or control boards - parts and labor for 3 years.
b) Compressors on refrigeration equipment - 5 years parts and 1 year labor.
c) Grinding burrs on coffee grinding equipment to grind coffee to meet original factory screen sieve analysis - parts

and labor for 4 years or 40,000 pounds of coffee, whichever comes first.

These warranty periods run from the date of installation BUNN warrants that the equipment manufactured by it will be
commercially free of defects in material and workmanship existing at the time of manufacture and appearing within the
applicable warranty period. This warranty does not apply to any equipment, component or part that was not manufactured
by BUNN or that, in BUNN’s judgment, has been affected by misuse, neglect, alteration, improper installation or operation,
improper maintenance or repair, non periodic cleaning and descaling, equipment failures related to poor water quality,
damage or casualty. In addition, the warranty does not apply to replacement of items subject to normal use including but
not limited to user replaceable parts such as seals and gaskets. This warranty is conditioned on the Buyer 1) giving BUNN
prompt notice of any claim to be made under this warranty by telephone at [phone] or by writing to Post Office
Box 3227, Springfield, Illinois 62708-3227; 2) if requested by BUNN, shipping the defective equipment prepaid to an
authorized BUNN service location; and 3) receiving prior authorization from BUNN that the defective equipment is under
warranty.

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.
If BUNN determines in its sole discretion that the equipment does not conform to the warranty, BUNN, at its exclusive op­tion while the equipment is under warranty, shall either 1) provide at no charge replacement parts and/or labor (during the
applicable parts and labor warranty periods specified above) to repair the defective components, provided that this repair
is done by a BUNN Authorized Service Representative; or 2) shall 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, AT BUNN’S SOLE OPTION
AS SPECIFIED HEREIN, TO REPAIR, 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.

392, AutoPOD, AXIOM, BrewLOGIC, BrewMETER, Brew Better Not Bitter, BrewWISE, BrewWIZARD, BUNN Espress, BUNN
Family Gourmet, BUNN Gourmet, BUNN Pour-O-Matic, BUNN, BUNN with the stylized red line, BUNNlink, Bunn-OMatic,
Bunn-O-Matic, BUNNserve, BUNNSERVE with the stylized wrench design, Cool Froth, DBC, Dr. Brew stylized Dr. design,
Dual, Easy Pour, EasyClear, EasyGard, FlavorGard, Gourmet Ice, Gourmet Juice, High Intensity, iMIX, Infusion Series, In­tellisteam, My Café, Phase Brew, PowerLogic, Quality Beverage Equipment Worldwide, Respect Earth, Respect Earth with
the stylized leaf and coffee cherry design, Safety-Fresh, savemycoffee.com, Scale-Pro, Silver Series, Single, Smart Funnel,
Smart Hopper, SmartWAVE, Soft Heat, SplashGard, The Mark of Quality in Beverage Equipment Worldwide, ThermoFresh,
Titan, trifecta, Velocity Brew, A Partner You Can Count On, Air Brew, Air Infusion, Beverage Bar Creator, Beverage Profit
Calculator, Brew better, not bitter., BUNNSource, Coffee At Its Best, Cyclonic Heating System, Daypart, Digital Brewer
Control, Nothing Brews Like a BUNN, Pouring Profits, Signature Series, Tea At Its Best, The Horizontal Red Line, Ultra are
either trademarks or registered trademarks of Bunn-O-Matic Corporation.

Page 2

32440 030912

CONTENTS

Introduction ................................................................2

User Notices ...............................................................3

Electrical Requirements ..............................................4

Plumbing Requirements .............................................4

Initial Set-Up ...............................................................5

Adjusting Brew Volumes .............................................6

Operating Controls ......................................................6

Coffee Brewing ............................................................7

Cleaning ......................................................................7

Troubleshooting ..........................................................8

Service ........................................................................12

Wiring Diagrams .........................................................28

INTRODUCTION

This equipment will brew a half-gallon batch of coffee into an awaiting decanter at the press of a button. The
OT has two and the RT has five warmers to keep the beverage at the right temperature, on the RT one of which
is capable of heating water to boiling. The brewer is only for indoor use on a sturdy counter or shelf.

USER NOTICES

Carefully read and follow all notices on the equipment and in this manual. They were written for your protection.
All notices on the equipment should be kept in good condition. Replace any unreadable or damaged labels.

WARNING !

Fill water tank before turning - on -
thermostat or connecting appliance
to power source.
Use only on a properly protected
circuit capable of the rated load.
Electrically ground the chassis.
Follow national/local electrical codes.
Do not use near combustibles.

FAILURE TO COMPLY RISKS EQUIPMENT

DAMAGE, FIRE, OR SHOCK HAZARD

READ THE ENTIRE OPERATING MANUAL

BEFORE BUYING OR USING THIS PRODUCT

THIS APPLIANCE IS HEATED WHENEVER

CONNECTED TO A POWER SOURCE

00831.0000F 3/98 ©1998 BUNN-O-MATIC CORPORATION

00831.0000

As directed in the International Plumbing Code of the
International Code Council and the Food Code
Manual of the Food and Drug Administration (FDA),
this equipment must be installed with adequate
backflow prevention to comply with federal, state
and local codes. For models installed outside the
U.S.A., you must comply with the applicable Plumb­ing /Sanitation Code for your area.

PN: 00658.0000G 02/08 © 1985 BUNN-O-MATIC CORPORATION

00658.0000

To reduce the risk of electric shock,
do not remove or open cover.
No user-serviceable parts inside.
Authorized service personnel only.
Disconnect power before servicing.

00656.0001

Page 3

37881.0000

32440 051512

ELECTRICAL REQUIREMENTS

200, 230 or

CAUTION - Do not connect the brewer to the power source until specified in Initial Set-Up.

L2 RED

MODELS OT15 & 20 require
2-wire, grounded service rated
120 volts ac, 15 or 20 amp
respectively, single phase, 60
Hz. Model 15 has an attached
cordset.

MODELS OT35 & RT35 require
3-wire, grounded service rated
120/208 or 120/240 volts ac, 20
amp, single phase, 60 Hz.

Electrical Hook-Up

Model OT15 has an attached cordset.
Models OT20, OT35, & RT35, proceed as follows:

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. Remove the front panel beneath the sprayhead
and rotate the control thermostat knob fully
counterclockwise to the “OFF” position and re­place the panel.

4. Remove the rear panel, feed the cord through
the strain relief, and connect it to the terminal
block.

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

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 Set-Up.

L1 BLACK

MODELS OTA, RTA & RT35B
require 2-wire, grounded ser­vice rated 240 volts ac or 200
volts ac, 20 amp single phase,
50 Hz.

240V A.C.

MODEL RT requires
2-wire, grounded service
rated 120 volt ac, 25 amp
single phase, 50 Hz.

P1709

Page 4

32440 010308

PLUMBING REQUIREMENTS

This brewer must be connected to a cold water system with operating pressure between 20 and 90 psi 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 to reduce it to 50 psi. The water inlet fitting is 1/4” flare.

NOTE - Bunn-O-Matic recommends 1/4” copper tubing for installations of less than 25 feet and 3/8” for more
than 25 feet 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 counter top. 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.

Plumbing Hook-Up

Model OT15 has an attached water strainer, proceed

to step 2.

Models OT20, OT35, & RT35, proceed as follows:

1. Remove the rear panel and bottom pan. Run the
long piece of tubing from the strainer (supplied)
under the brewer and attach it to the water inlet
fitting on the solenoid. Reinstall the bottom pan
and rear panel.

2. Flush the water line and securely attach it to the
1/4” flare fitting on the strainer.

3. Turn on the water supply.

P1709

As directed in the International Plumbing Code of the International Code Council and the Food Code Manual
of the Food and Drug Administration (FDA), this equipment must be installed with adequate backflow pre­vention to comply with federal, state and local codes. For models installed outside the U.S.A., you must
comply with the applicable Plumbing /Sanitation Code for your area.

Page 5

INITIAL SETUP

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

specified in the instructions.

1. Remove the front panel.

2. Rotate the control thermostat knob fully counter­clockwise to the “OFF” position and replace the
panel.

3. Insert an empty funnel into the funnel rails.

4. Place a decanter containing a small amount of
water on the warmer beneath the funnel.

5. Connect the brewer to the power source, place
the On/Off brew station warmer switch the up­per position, and momentarily press the
start switch. Water will begin flowing into
the tank. When water stops flowing into the tank,
initiate a second and a third brew cycle. During
this third brew cycle the tank will fill to its
capacity and the excess will flow from the spray­head, out of the funnel, and into the decanter.

NOTE - The On/Off brew station warmer switch must
be in the upper position to initiate and complete a
brew cycle.

6. Place the On/Off brew station warmer switch in
the lower position.

7. Disconnect the brewer from the power source.

8. Remove the front panel.

9. Rotate the control thermostat knob fully clock­wise to the “ON” position and replace the front
panel.

10. Connect the brewer to the power source and wait
approximately twenty minutes for the water in the
tank to heat to the proper temperature. Some
water will drip from the funnel during this time;
this is due to expansion and should not occur
thereafter.

11. Place an empty decanter under the funnel.

12. Place the On/Off brew station warmer switch in
the upper position and momentarily press the
start switch. Empty the decanter after water has
stopped flowing from the funnel.

13. Allow the water in the tank to reheat to the proper
temperature.

14. Place an empty decanter on the warmer and press
the start switch. Check the water volume in the
decanter after water has stopped flowing from
the funnel. It should be 64 ounces.

15. If not, adjust the Timer as described in Adjusting
Brew Volumes (page 6)

16. Repeat steps 13-15 until 64 oz water volume is
achieved.

P1687

Page 6

P1690

32440 070700

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 and server are in place.

1. Modifying batch sizes. To modify a batch volume, first check that the SET/LOCK switch is in the “SET” posi-

tion on the circuit board.

To increase a batch size. Press and hold the START or BREW switch until three clicks are heard. Release

the switch (Failure to release the switch within two seconds after the third click 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 three clicks are heard. Release the switch. (Failure to release the switch within two seconds after
the third click 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 three distinct clicks are heard, and then
release the switch. (Failure to release the switch within two seconds after the third click 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.

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.

OPERATING CONTROLS

MODELS OT & RT
A. On/Off Brew Station Warmer Switch

Placing the switch in the upper position supplies
power to the brew station warmer and enables brew­ing. Placing the switch in the lower position cuts
power to the brew station warmer and stops brewing.
Stopping a brew cycle after it has been started will not
stop the flow of water into the funnel until the tank
syphons down to its proper level.

NOTE - The On/Off brew station warmer switch must
be in the upper position to initiate and complete a
brew cycle.

B. On/Off Brew Station Warmer Indicator Lamp

Glows whenever the On/Off brew station warmer
switch is in the upper position showing that the
warmer is on and that the automatic brew cycle can
be started.

C. Start Switch

Starts a brew cycle when the On/Off brew station
warmer switch is in the upper position.

D. Upper Warmer Switch

Placing the switch in the upper position supplies
power to the upper warmer. Placing the switch in the
lower position cuts power to the upper warmer.

E. Upper Warmer Indicator Lamp

Glows whenever the upper warmer switch is in the
upper position showing that the warmer is on.

F. Left Rear Warmer Rotary Switch

Rotating the knob to the “ON” position supplies power
to the left rear warmer. Rotating the knob to the “OFF”
position cuts power to the left rear warmer.

G. Left Front Warmer Rotary Switch

Rotating the knob to the “ON” position supplies power
to the left front warmer. Rotating the knob to the “OFF”
position cuts power to the left front warmer.

H. Right Front Warmer Rotary Switch

Rotating the knob to the “ON” position supplies power
to the right front warmer. Rotating the knob to the
“OFF” position cuts power to the right front warmer.

I. Right Rear Warmer Rotary Switch

Rotating the knob to the “ON” position supplies power
to the right rear warmer. Rotating the knob to the
“OFF” position cuts power to the right rear warmer.

Page 7

32440 121699

MODEL OT

MODEL RT

D E

A B C

COFFEE BREWING

P1687

P1688

F G A B C H I

Start each brew cycle with an empty, clean, half-gallon decanter.

1. Insert a BUNN® filter into the funnel.

2. Pour the fresh coffee into the filter and level the bed of grounds by gently shaking.

3. Slide the funnel into the funnel rails.

4. Place the On/Off brew station warmer switch in the upper position.

5. Momentarily press the start switch.

6. When brewing is completed, simply discard the grounds and filter.

CLEANING

1. The use of a damp cloth rinsed in any mild, non-abrasive, liquid detergent is recommended for cleaning all
surfaces on Bunn-O-Matic equipment.

2. Check and clean the sprayhead. The sprayhead holes must always remain open.

3. With the sprayhead removed, insert the deliming spring (provided) all the way into the sprayhead tube. When
inserted properly, no more than two inches of spring should be visible. Saw back and forth five or six times.
Then, repeat this step for the air vent tube.

NOTE - In hard water areas, this may need to be done daily. It will help prevent liming problems in the brewer
and takes less than a minute.

NEEDLE VALVE ADJUSTMENT (Models with Faucet)

This brewer is equipped with a unique faucet system allowing hot water to be drawn-off a cup-at-a-time for
instant beverage needs, even while brewing.
WARNING - Disconnect the brewer from the power source before the removal of any panel or replacement of
any component.

ADJUSTMENT

1. Disconnect the brewer from the power source and remove the front inspection panel located beneath the
brew funnel.

2. Adjust the needle valve as required to increase or decrease the pressure of the hot water flowing from the
faucet. Turn the propeller on the valve in a counterclockwise direction to increase the flow and in a clockwise
direction to decrease the flow.

3. Reconnect the brewer to the power source and allow the water in the tank to heat to the proper temperature
before operating the brewer.

Page 8

32440 121699

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qualiedserviceperson­nel.

• Allelectriccomponentshave120voltacvoltageontheirterminals.Shortingofterminalsortheapplication

of external voltages may result in equipment failure.

• Intermittentoperationofelectronicequipmentisunlikely.Component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ttings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unlessdisconnectedfromthepowersource.Keepawayfromcombus-

tibles.

WARNING

• Exerciseextremecautionwhenservicingelectricalequipment.

• Disconnectthebrewerfromthepowersourcewhenservicing,exceptwhenelectricaltestsarespecied.

• Followrecommendedserviceprocedures

• Replaceallprotectiveshieldsorsafetynotices

Problem

Equipment will not operate.

Brew cycle will not start.

Probable Cause

1. No power or incorrect voltage

1. No water

2. Water Strainer

3. Flow Control

Remedy

(A) Connect the brewer to the power
source.

(B) Check the terminal block for the
proper voltages.

(C) Check circuit breaker/fuse.

Check plumbing and shut-off
valves.

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

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

(A) Direction of flow arrow must be
pointing away from the solenoid.

Page 9

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

32440 121699

TROUBLESHOOTING (cont.)

Problem

Brew cycle will not start. (cont.)

Water flows into tank continuously
(On/Off brew station warmer switch
“OFF”).

Water flows into tank continuously
(On/Off brew station warmer switch
“ON”).

Probable Cause

4. On/Off Brew Station Warmer
Switch

5. Start Switch

6. Brew Timer

7. Solenoid Valve

1. Solenoid Valve

1. Brew Timer

Remedy

Refer to Service - On/Off Brew
Station Warmer Switch for testing
procedures. See page 18.

Refer to Service - Start Switch for
testing procedures. See page 23.

Refer to Service - Timer for testing
procedures. See page 13 & 14.

Refer to Service - Solenoid Valve for
testing procedures. See page 22.

Refer to Service - Solenoid Valve for
testing procedures. See page 22.

Refer to Service - Timer for testing
procedures. See page 13 & 14.

Water is not hot.

Decanter warmer is not hot.

1. Limit Thermostat

CAUTION

Do not eliminate or bypass limit
thermostat. Use only B.O.M. replace­ment part #29329.1000

2. Control Thermostat

3. Tank Heater

1. Warmer Switches

Refer to Service - Limit Thermostat
for testing procedures. See page

21.

Refer to Service - Control Thermo­stat for testing procedures. See
page 16.

Refer to Service - Tank Heater for
testing procedures. See page 24.

(A) The Warmer Switch(es) must be
in the “ON” position for the warmer
to operate.

(B) Refer to Service - Warmer
Switch(es) for testing procedures.
See pages 18 & 19.

2. Decanter Warmers

Page 10

Refer to Service - Warmers for test­ing procedures. See page 17.

32440 070700

TROUBLESHOOTING (cont.)

Problem

Spitting or unusual steaming from
sprayhead.

Inconsistent beverage level in de­canter.

Probable Cause

1. Control Thermostat

2. Lime build-up

CAUTION

Tank and tank components should
be delimed regularly depending on
local water conditions. Excessive
mineral build-up on stainless steel
surfaces can initiate corrosive reac­tions resulting in serious leaks.

1. Flow control

Remedy

Refer to Service - Control Thermo­stat for testing procedures. See
page 16.

Inspect the tank assembly for ex­cessive lime deposits. Delime as
required.

(A) Direction of flow arrow must be
pointing away from the solenoid.

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

Consistently high or low beverage
level in decanter.

Dripping from sprayhead.

2. Improper water pressure

3. Syphon system

1. Brew Timer adjustment

1. Syphon system

Check the operating water pressure
to the brewer. It must be between 20
and 90 psi (138 and 620 kPa).

Water should flow freely from the
sprayhead for approximately twenty
seconds after the brew solenoid
has shut-off and then stop flow­ing abruptly. The brewer must be
level from front-to-back to syphon
properly.

Adjust the brew timer as required to
achieve the recommended 64 oz for
each brew cycle.

Water should flow freely from the
sprayhead for approximately twenty
seconds after the brew solenoid
has shut-off and then stop flow­ing abruptly. The brewer must be
level from front-to-back to syphon
properly.

2. Solenoid Valve

Page 11

Refer to Service - Solenoid Valve for
testing procedures. See page 22.

32440 070700