Bunn Coffee Maker STF MODELS Installation Manual

BUNN

S,SA

ST,STA

STF,STFA

OPERATING & SERVICE MANUAL

BUNN-O-MATIC CORPORATION

POST OFFICE BOX 3227

SPRINGFIELD, ILLINOIS 62708-3227

PHONE: (217) 529-6601 FAX: (217) 529-6644

www.bunnomatic.com

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 three 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.

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USER NOTICES

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USER NOTICES (Continued)

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ELECTRICAL REQUIREMENTS

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

Model 15 has an attached cordset and requires 2-wire grounded service rated 120 volts ac, 15 amp, single

phase, 60 Hz.

Initial Set-Up.

WHITE

NEUTRAL L1 BLACK

120V.A.C.

P2185

Model 20 requires 2wire, grounded service rated 120 volts ac, 20 amp, single phase, 60 Hz. Proceed as follows:

L2 RED

WHITE

NEUTRAL

L1 BLACK

120V A.C.

208 or

240V.A.C.

P1841

Model 35 requires 3-

wire, grounded service rated 120/208 or 120/240 volts ac, 20 amp, single phase, 60 Hz. Proceed as follows:

P2193

“A" & "B” models re-

quire 2-wire, grounded service rated 200 volts ac or 240 volts ac, 20 amp, single phase, 50 Hz. Proceed as follows:

WHITE

NEUTRAL L1 BLACK

100V.A.C.

P2185

"SDB” model requires

2-wire, grounded service rated 100 volts ac, 20 amp, single phase, 50 Hz. Proceed as follows:

Electrical Hook-Up 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 and rear panel and rotate the thermostat knob fully

counterclockwise to the "OFF" position. Keep this knob in the "OFF" position until performing the "Initial Set-Up"

4. Feed the power 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.

(Models S and ST-15 have cord attached. Replace all panels.

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".

NOTE: Schematic wiring diagrams are included in this manual.

PLUMBING REQUIREMENTS

Models S & SA:

These models are completely portable and require no attached plumbing.

Models ST, STA, STF & STFA

These brewers must be connected to a cold water system with operating pressure between 20 and 90 psi (138 and 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 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 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).

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INITIAL SET-UP

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

specified in the instructions.

1. Insert an empty funnel into the funnel rails.

2. Place an empty dispenser under the funnel.

3. Remove the front or rear panel and turn the thermostat knob to the “OFF” position and connect the brewer to the power source.

4. Fill the tank with water as directed:

4A. Models S & SA:

Pour three pitchers of tap water into the screened area on top of the brewer. Allow approximately two minutes between pitchers for water to flow into the tank. While the third pitcher of water is entering the tank, the tank will fill to capacity and the excess will flow from the sprayhead, out of the funnel, and into the dispenser.

4B. Models ST, STA:

Connect the brewer to the power source, place the "ON/OFF" switch in the "ON" upper position, and momentarily press and release 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 the 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 dispenser.

4C. Models STF & STFA

Brewers will fill automatically when lower ON/OFF switch is placed in the "ON" position and tank will fill to capacity.

5. When the flow of water from the funnel stops, turn the thermostat knob to the “ON” position 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.

6. Empty the dispenser and initiate another brew cycle as directed:

6A. Models S & SA:

Pour one pitcher of tap water into the screened area on top of the brewer.

6B. Models ST, STF, STA & STFA:

Place the "ON/OFF" switch in the "ON" upper position, and momentarily press and release the start switch.

7. Place the "ON/OFF" switch in the lower “OFF” position after water has stopped flowing from the funnel, and let the water in the tank reheat to the proper temperature.

8. Empty the dispenser and proceed as directed:

8A. Models S & SA:

The brewer is now ready for use in accordance with the coffee brewing instructions on the next page.

8B. Models ST, STF, STA & STFA:

Place the "ON/OFF" switch in the "ON" upper position, and momentarily press and release the start switch. Check the water volume in the dispenser after water has stopped flowing from the funnel. It should be 64 ounces.

9. If not, disconnect the brewer from the power source. On early models remove the access panel. Adjust the timer as required (see service section). Replace the panel, connect the brewer to the power source, and allow the water to reheat, start, and measure another brew cycle.

10. Repeat step 9 until 64 oz water volume is achieved.

11. The brewer is now ready for use in accordance with the coffee brewing instructions on the next page.

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OPERATING CONTROLS

Models S & SA:

These models function without operating controls.

Models ST, STF, STA & STFA: ON/OFF SWITCH

Placing the "ON/OFF" switch in the "OFF" lower position 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. Placing the switch in the "ON" upper position supplies power to the brew station warmer and enables the brew circuit and on Models STF and STFA refills the tank.

START SWITCH

Momentarily pressing and releasing the switch starts a brew cycle when the "ON/OFF" switch is in the "ON" upper position.

NOTE – The "ON/OFF" switch must be in the "ON" upper position to initiate and complete a brew cycle.

COFFEE BREWING

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 an empty dispenser beneath the funnel.

5. Operate the brewer as directed:

5A. Models S & SA:

Pour one pitcher of tap water into the screened area on top of the brewer.

5B. Models ST, STF, STA & STFA:

Place the "ON/OFF" switch in the "ON" upper position. Momentarily press and release 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.

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.

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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 (ST, STF, STA & STFA)

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 across the black and white terminals on two wire 120 volt brewers. (A2) Check the terminal block for 120 volts across the red and white terminals and the black and white terminal on three wire 120/240 volt brewers. (A3) Check the terminal block for 200 volts on Model STFB brewers or 240 volts on "A Series" brewers across the red and black terminals. (A4) Check the terminal block for 100 volts on Model SDB brewers across the white and black terminals.

Page 7

(B) Check circuit breakers or fuses.

29251 101598

TROUBLESHOOTING (cont.)

PROBLEM

Brew cycle will not start (cont.) (ST, STF, STA & STFA)

PROBABLE CAUSE

3. ON/OFF switch

4. Start switch

5. Timer

6. Solenoid valve

7. Strainer/flow control (.222 GPM)

REMEDY

Refer to

Service

- ON/OFF Switch

for testing. See page 17

Refer to

Service

- Start Switch for

testing procedures. See page 19

Refer to

Service

- Timer for testing

procedures. See page 22 or 24

Refer to

Service

- Solenoid Valve for testing procedures. See page 18

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

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

Water is not hot

Inconsistent beverage level in dispenser

1. Limit thermostat CAUTION - Do not eliminate or bypass limit thermostat. Use only BOM replacement part #29329.

1000.

2. Control thermostat

3. Tank heater

1. Strainer /flow control (.222 GPM) (ST, STF, STA & STFA)

Refer to

Service

- Limit Thermostat for testing procedures. See page 16

Refer to

Service

- Control Thermostat for testing procedures. See page 14

Refer to

Service

- Tank Heater for

testing procedures. See page 20

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

(B) Remove the strainer/flow control and check for obstruction. Clear or replace.

2. Liquid level board or level probe

Page 8

Refer to

Service

- Liquid Level Board for testing procedures. See page 26

29251 052500

TROUBLESHOOTING (cont.)

PROBLEM

Inconsistent beverage level in dispenser (cont.)

Consistently low beverage level in the dispenser (ST, STF, STA & STFA)

PROBABLE CAUSE

3. Syphon system

4. 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.

5. Water pressure (ST, STF, STA & STFA)

1. Timer

REMEDY

The brewer must be level or slightly lower in front to syphon properly.

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

The water pressure to the brewer must be at least 20 psi (138 kPa).

(A) Early models-Timer dial must indicate at least two minutes and fifteen seconds.

Spitting or excessive steaming

2. Strainer/flow control (.222 GPM)

1. 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.

2. Control thermostat

(B) Refer to

Service

- Digital Timer for testing procedures. See page 24

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

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

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

Refer to

Service

- Control Thermostat for testing procedures. See page 14

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TROUBLESHOOTING (cont.)

PROBLEM

Dripping from sprayhead

Water flows into tank continuously (ON/OFF Switch "ON")

PROBABLE CAUSE

1. Syphon system

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.

3. Solenoid valve (ST, STF, STA & STFA)

1. Timer (ST, STF, STA & STFA)

REMEDY

The brewer must be level or slightly lower in front to syphon properly.

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

Remove the solenoid valve and clear any obstructions. Rebuild or replace the valve if necessary. See page 18

Refer to

Service -

Timer for testing

procedures. See page 22 or 24

Water flows into tank continuously (ON/OFF Switch "OFF")

Beverage overflows dispenser

2. Start switch

3. Liquid level board

4. Relay

1. Solenoid valve (ST, STF, STA & STFA)

1. Dispenser

2. Timer (ST, STF, STA & STFA)

Refer to

Service

- Start Switch for

testing procedures. See page 19

Refer to

Service

- LiquidLevel Board for testing procedures. See page 26

Refer to

Service

- Relay for testing

procedures. See page 28

Remove the Solenoid Valve and clean any obstruction. Rebuild or replace the valve if necessary. See page 18

The dispenser must be completely empty before starting a brew cycle.

Refer to

Service -

Timer for testing

procedures. See page 22 or 24

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TROUBLESHOOTING (cont.)

PROBLEM

Beverage overflows dispenser (cont.)

Weak beverage

PROBABLE CAUSE

3. Solenoid valve (ST, STF, STA & STFA)

1. Filter type

2. Coffee grind

3. Sprayhead

4. Funnel loading

REMEDY

Remove the Solenoid Valve and clean any obstruction. Rebuild or replace the valve if necessary. See page 18

The BUNN® paper filter must be used for proper extraction.

A fine or drip grind must be used for proper extraction.

A six-hole stainless steel sprayhead must be used for proper extraction.

The BUNN® paper filter must be centered in the funnel and the bed of ground leveled by gentle shaking.

Dry coffee grounds remain in the funnel

Brewer is making unusal noises (ST, STF, STA & STFA)

5. Water temperature

1. Funnel loading

1. Solenoid valve

2. Plumbing lines

Place an empty funnel on an empty dispenser beneath the sprayhead. Initiate a brew cycle and check the water temperature immediately below the sprayhead with a thermometer. The reading should not

be less than 195°F. Adjust the

control thermostat to increase the water temperature. Replace if necessary.

The BUNN® paper filter must be centered in the funnel and the bed of grounds leveled by gently shaking.

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

Plumbing lines should not resting on the counter top.

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TROUBLESHOOTING (cont.)

PROBLEM

Brewer is making unusal noises (ST, STF, STA & STFA)(cont.)

Automatic refill will not operate

PROBABLE CAUSE

3. Water supply

4. Tank heater

1. No water

2. Strainer/flow control

REMEDY

(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 working pressure to approximately 50 psi (345 kPa).

Remove and clean lime off the tank heater. See page 20

Check plumbing

A. Direction of arrow must be pointing towards brewer.

B. Remove the strainer/flow control and check for obstructions. Clean or replace.

Beverage not staying hot in dispenser

3. Solenoid valve

4. Liquid level control board or level probe

5. Relay

1. ON/OFF switch

2. Warmer elements

Refer to

Service

- Solenoid Valve for testing procedures. See page 18

Refer to

Service

- Liquid level control board or level probe for testing procedures. See page 26

Refer to

Service

- Relay for test-

ing procedures. See page 28

Refer to

Service

- ON/OFF switch for testing procedures. See page 17

Refer to

Service

- Warmer elements for testing procedures. See page 29

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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 top cover or top warmer housing and front and rear inspection panels.

for assistance in determining the

The top cover for Models with no top warmer and the top warmer housing is attached with four #8-32 screws. Unplug upper wiring harness and set housing aside.

The front and rear inspection panels are attached with four #8-32 screws each.

Contents

Control Thermostat............................................. 14

Limit Thermostat ................................................ 16

ON/OFF Switch.................................................... 17

Solenoid ............................................................. 18

Start Switch (Brew) ............................................ 19

Tank Heater ........................................................ 20

Brew Timer (Early Models) ................................. 22

Digital Timer (Late Models) ................................ 24

Liquid Level Board ............................................. 26

Relay.................................................................. 28

Warmer Element ................................................ 29

Thermal Cut-off ................................................. 30

Wiring Diagrams.................................... 31 thru 43

P1584

FIG. 1 COMPONENT ACCESS

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29251 052500

SERVICE (cont.)

CONTROL THERMOSTAT

U N

Test Procedures:

1. Disconnect the brewer from the power source.

2. Locate the blue wire on the control thermostat.

3. Check the voltage across the blue wire on the control thermostat and the white insert on two pole 100 or 120 volt terminal block or three pole 120/240 volt terminal blocks and the red insert on two wire 200 volt or 240 volt terminal block with a voltmeter. Connect the brewer to the power source. The indication must be: a) 120 volts ac for two wire 120 volt models and three wire 120/240 volt models. b) 200 to 240 volts ac for two wire 200 or 240 volt models. c) 100 volts ac for two wire 100 volt models.

4. Disconnect the brewer from the power source.

If voltage is present as described, proceed to #5. If voltage is not present as described, refer to the

Diagrams

and check the brewer wiring harness.

Wiring

FIG. 2 CONTROL THERMOSTAT

Location:

Models S & SA: The control thermostat is mounted on a bracket inside the rear inspection cover on the left side. Models ST, STA, STF & STFA: The control thermostat is located inside the front inspection cover on the component mounting bracket.

P1585

Page 14

5. Locate the black wire on the control thermostat.

6. Gently remove the capillary bulb and grommet from the tank.

7. Check the voltage across the black wire of the control thermostat and the white insert on the two pole 100 or 120 volt or three pole 120/240 volt terminal block and the red insert on the two pole 200 volt or 240 volt terminal block with a voltmeter when the control thermostat is turned "ON" (Fully clockwise). Connect the brewer to the power source. The indication must be: a) 120 volts ac for two wire 120 volt models and three wire 120/240 volt models. b) 200 to 240 volts ac for two wire 200 volt or 240 volt models. c) 100 volts ac for two wire 100 volt models.

8. Disconnect the brewer from the power source.

If voltage is present as described, reinstall the capillary tube into the tank to the line 4.5" above the bulb, the control thermostat is operating properly. If voltage is not present as described, replace the thermostat.

29251 052500

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