Bunn STF, STA, STFA, ST, SA User Manual

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BUNN® S,SA

ST,STA

STF,STFA

DISCONTINUED VERSION

The information in this manual

is no longer current.

OPERATING & SERVICE MANUAL

BUNN-O-MATIC CORPORATION

POST OFFICE BOX 3227

SPRINGFIELD, ILLINOIS 62708-3227

PHONE: (217) 529-6601

FAX: (217) 529-6644

29251.0000G 04/01 ©1998 Bunn-O-Matic Corporation

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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Page 2

29251 042301

 

USER NOTICES (Continued)

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Page 3

29251 101598

 

 

 

 

 

ELECTRICAL REQUIREMENTS

CAUTION - The brewer must be disconnected from the power source until specified in Initial Set-Up.

Model 15 has an attached cordset and requires 2-wire grounded service rated 120 volts ac, 15 amp, single phase, 60 Hz.

WHITE

L2 RED

 

 

WHITE

 

 

 

 

 

 

120V A.C.

 

 

 

 

WHITE

 

NEUTRAL

 

NEUTRAL

208 or

 

100V.A.C.

120V.A.C.

 

L1 BLACK

L1 BLACK

240V.A.C.

 

 

NEUTRAL

120V A.C.

 

 

 

 

 

 

 

 

L1 BLACK

 

 

 

 

 

P2185

P1841

P2193

 

P2185

 

 

 

 

 

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

Model 35 requires 3- wire, grounded service rated 120/208 or 120/240 volts ac, 20 amp, single phase, 60 Hz. Proceed as follows:

“A" & "B” models require 2-wire, grounded service rated 200 volts ac or 240 volts ac, 20 amp, single phase, 50 Hz. Proceed as follows:

Electrical Hook-Up

CAUTION – Improper electrical installation will damage electronic components.

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

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 12" 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 14" flare.

NOTE - Bunn-O-Matic recommends 14" copper tubing for installations of less than 25 feet and 38" for more than 25 feet from the 12" 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).

Page 4

29251 011800

 

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.

Page 5

29251 052500

 

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.

Page 6

29251 101598

 

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

PROBABLE CAUSE

REMEDY

Brew cycle will not start (ST, STF,

1. No water

Waterlinesandvalvestothebrewer

STA & STFA)

 

must be open.

 

2. No power or incorrect voltage to

(A1) Check the terminal block for

 

the brewer

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 termi-

 

 

nals.

 

 

(A4) Check the terminal block for

 

 

100 volts on Model SDB brewers

 

 

across the white and black termi-

 

 

nals.

 

 

(B) Check circuit breakers or fuses.

 

Page 7

29251 101598

 

 

TROUBLESHOOTING (cont.)

 

 

 

 

PROBLEM

PROBABLE CAUSE

 

REMEDY

Brew cycle will not start (cont.)

3. ON/OFF switch

 

Refer to Service - ON/OFF Switch

(ST, STF, STA & STFA)

 

 

 

for testing. See page 17

 

4.

Start switch

 

Refer to Service - Start Switch for

 

 

 

 

testing procedures. See page 19

 

5.

Timer

 

Refer to Service - Timer for testing

 

 

 

 

procedures. See page 22 or 24

 

6.

Solenoid valve

 

Refer to Service - Solenoid Valve

 

 

 

 

for testing procedures. See page

 

 

 

 

18

 

7.

Strainer/flow control

(.222

(A) Direction of flow arrow must

 

GPM)

 

be pointing towards brewer.

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

Water is not hot

1. Limit thermostat

 

CAUTION - Do not eliminate or

 

bypass limit thermostat. Use only

 

BOM replacement part #29329.

 

1000.

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

2. Control thermostat

Refer to Service - Control Ther-

 

mostat for testing procedures. See

 

page 14

Inconsistent beverage level in dispenser

3. Tank heater

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

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

Refer to Service - Liquid Level

 

Board for testing procedures. See

 

page 26

Page 8

29251 052500

 

TROUBLESHOOTING (cont.)

PROBLEM

Inconsistent beverage level in dispenser (cont.)

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

Spitting or excessive steaming

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

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

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.

(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

Page 9

29251 052500

 

TROUBLESHOOTING (cont.)

 

 

PROBLEM

PROBABLE CAUSE

REMEDY

Dripping from sprayhead

1. Syphon system

The brewer must be level or slightly

 

 

lower in front to syphon properly.

 

2. Lime build-up

Inspect the tank assembly for ex-

 

CAUTION - Tank and tank compo-

cessive lime deposits. Delime as

 

nents should be delimed regularly

required.

 

depending on local water condi-

 

 

tions. Excessive mineral build-up

 

 

on stainless steel surfaces can ini-

 

 

tiate corrosive reactions resulting

 

 

in serious leaks.

 

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

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

See page 18

Water flows into tank continuously

1.

Timer (ST, STF, STA & STFA)

Refer to Service - Timer for testing

(ON/OFF Switch "ON")

 

 

procedures. See page 22 or 24

 

2.

Start switch

Refer to Service - Start Switch for

 

 

 

testing procedures. See page 19

 

3.

Liquid level board

Refer to Service - LiquidLevel

 

 

 

Board for testing procedures. See

 

 

 

page 26

 

4. Relay

Water flows into tank continuously

1. Solenoid valve (ST, STF, STA &

(ON/OFF Switch "OFF")

STFA)

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

Beverage overflows dispenser

1.

Dispenser

The dispenser must be completely

 

 

 

empty before starting a brew cycle.

 

2.

Timer (ST, STF, STA & STFA)

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

Dry coffee grounds remain in the funnel

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

PROBABLE CAUSE

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

1.Filter type

2.Coffee grind

3.Sprayhead

4.Funnel loading

5.Water temperature

1. Funnel loading

1.Solenoid valve

2.Plumbing lines

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.

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

PROBABLE CAUSE

REMEDY

Brewer is making unusal noises

3. Water supply

(A) The brewer must be connected

(ST, STF, STA & STFA)(cont.)

 

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 ap-

 

 

proximately 50 psi (345 kPa).

 

4. Tank heater

Remove and clean lime off the

 

 

tank heater. See page 20

Automatic refill will not operate

1. No water

Check plumbing

 

2. Strainer/flow control

A. Direction of arrow must be

 

 

pointing towards brewer.

 

 

B. Remove the strainer/flow con-

 

 

trol and check for obstructions.

 

 

Clean or replace.

 

3. Solenoid valve

Refer to Service - Solenoid Valve

 

 

for testing procedures. See page

 

 

18

 

4. Liquid level control board or

Refer to Service - Liquid level con-

 

level probe

trol board or level probe for test-

 

 

ing procedures. See page 26

 

5. Relay

Refer to Service - Relay for test-

 

 

ing procedures. See page 28

Beverage not staying hot in dis-

1. ON/OFF switch

Refer to Service - ON/OFF switch

penser

 

for testing procedures. See page

 

 

17

 

2. Warmer elements

Refer to Service - Warmer ele-

 

 

ments 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 for assistance in determining the

 

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 re-

 

quired 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 replace-

 

ment of any component.

 

 

All components are accessible by the removal of

 

the top cover or top warmer housing and front and rear

 

inspection panels.

 

 

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

P1584

 

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

 

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

FIG. 1 COMPONENT ACCESS

 

Page 13

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SERVICE (cont.)

CONTROL THERMOSTAT

BU

NN

HI

P1585

FIG. 2 CONTROL THERMOSTAT

Location:

ModelsS&SA:Thecontrolthermostatismounted 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.

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 Wiring Diagrams and check the brewer wiring harness.

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.

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