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Bunn DUAL 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
OPERATING & SERVICE MANUAL
DUAL
™
(Serial # DUAL010000 - Up)
27040.0000F 01/04 ©1996 Bunn-O-Matic Corporation
C A
U T
I O
N :
W
A R
M
E R
S
A N
D
S U
R F
A C
E S
A
R E
H
O
T
CAUTION
DISCARD DEC
ANTER
IF:
. C
RA
CK
ED
. S
CR
AT
CH
ED
. B
OILE
D D
RY
. H
EA
TE
D W
HE
N E
MP
TY
. U
SED
O
N H
IG
H FL
AM
E
. O
R E
XP
OS
ED
E
LE
CT
RIC
E
LE
MEN
TS
FAILURE TO C
OMPLY RISKS
INJURY
PN
: 6
58
19
85
B
UN
N-O
-M
AT
IC
C
OR
PO
RA
TIO
N
FUNNEL CONT
ENT
S
ARE HOT
!
START
ON / WARMER
SELECTOR
READY
READY
ON / WARMER
START
1
1⁄2
gal
1 gal
1⁄2
ga
l
SELECTOR
1
1⁄2
gal
1 ga
l
1⁄2
gal
!
CAUTION
HOT WATER
GR
IN
DER
L
E
F
T
R
I
G
H
T
DISCONNECT FROM POWER SOURCE
BEFORE REMOVAL OF ANY PANEL OR
REPLACEMENT OF
ANY COMPONENT!
W
AR
NIN
G
!
Summary of DUAL
Page 1
Bunn-o-matic corporation post office box 3227 springfield, illinois 62708-3227 phone: (217) 529-6601 fax: (217) 529-6644 www.Bunnomatic.Com operating & service manual dual ™ (serial # dual010000 - up) 27040.0000f 01/04 ©1996 bunn-o-matic corporation c a u t i o n : w a r m e r s a n d s u r f a c e ...
Page 2
Page 2 introduction this equipment will brew two half-gallon, gallon, or gallon and a half batches of coffee into awaiting servers at the push of a button. The brewer is also equipped with a hot water faucet for allied beverage use and is designed to interface with a bunn ® grinder. The brewer is sp...
Page 3
Page 3 requires 2-wire, grounded service rated 200 to 240 volts ac, 30 amp, single phase 50 or 60 hz. Requires 3-wire, grounded service rated 120/208 or 120/ 240 volts ac, 30 amp, single phase, 60 hz. 120v a.C. 120v a.C. 120v a.C. 208 or 240v a.C. L2 red l2 red white neutral l1 black l1 black 200 or...
Page 4
Page 4 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 sprayheads. ...
Page 5
Page 5 27040 011904 models with electronic control assemblies: place the tank heater switch at the top of the control assembly in the “on” position and replace the front panel. Models with electro/mechanical thermostats: rotate the control thermostat knob fully clockwise to the “on” position and rep...
Page 6
Page 6 27040 011904 8. Repeat step 7 until the proper water volume is achieved. 9. Repeat steps 5 through 8 for the remaining brew station. 10. The brewer is now ready for use in accordance with the coffee brewing instructions. Adjusting brew volumes caution - disconnect the power source from the br...
Page 7
Page 7 coffee brewing 1. Select the desired batch size. 2. Insert a bunn ® filter into the funnel. 3. Pour the proper amount of fresh ground coffee into the filter and level the bed of grounds by gently shaking. 4. Slide the funnel into the funnel rails. 5. Place an empty server under the funnel. 6 ...
Page 8
Page 8 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 ...
Page 9
Page 9 troubleshooting (cont.) problem brew cycle will not start (cont.) automatic refill will not operate remedy refer to service - on/off switch for testing procedures. See page 32 refer to service - start switch for testing procedures. See page 37 refer to service - timer for testing procedures. ...
Page 10
Page 10 troubleshooting (cont.) problem beverage level will not adjust (selector switch in any position) water flows into tank continuously . Water flows into tank continuously (on/off switch "on"). Water from tank is not hot probable cause 1. Brew selector switch 1. Solenoid valve 2a. Level control...
Page 11
Page 11 troubleshooting (cont.) problem water from tank is not hot (cont.). Server warmer is not hot. Spitting or unusual steaming from sprayhead or airvents. Inconsistent beverage level in server. Probable cause 6. Relay (brewers with recovery booster) 1. On/off switch 2. Warmer element 1a. Control...
Page 12
Page 12 troubleshooting (cont.) problem inconsistent beverage level in server (cont.). Consistently high or low beverage level in server. Dripping from sprayhead. Water overflows filter. Beverage overflows server. Weak beverage. Probable cause 3. Dispense valve 1. Timer adjustment 1. Dispense valve ...
Page 13
Page 13 troubleshooting (cont.) problem weak beverage (cont.) brewer is making unusual noises. Probable cause 3. Sprayhead 4. Funnel loading 5. Water temperature 1. Solenoid (inlet) 2. Plumbing lines 3. Water supply 4. Tank heaters 5. Contactor remedy a clean sprayhead should be used to properly wet...
Page 14
Page 14 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 electri- cal equipmen...
Page 15
Page 15 service (cont.) bypass valve location: the bypass valves are located inside the right front and the center front of the hood. Test procedures: 1. Disconnect the brewer from the power source and place a server beneath the funnel. 2. Check the water level in the tank to confirm that it is with...
Page 16
Page 16 service (cont.) brew selector switch location: the brew selector switches are located in the front left and right side of the hood. Test procedure: 1. Disconnect the brewer from the power supply. 2. Separate the connector on the selector switch harness from the brew timer circuit board. 3. C...
Page 17
Page 17 service (cont.) p776 27040 032201 to left or right timer tan gry pnk whi/vio to left or right by-pass valve whi/red to left or right dispense valve gry to left or right selector switch to gry lead on interface socket pnk from left switch to grinder switch (lower left) pnk from right switch t...
Page 18
Page 18 service (cont.) contactor assembly location: the contactor assembly is located inside the hood just to the rear of the right dispense valve. Test procedures: mechanical thermostat (brewers with or without recovery booster) 1. Disconnect the brewer from the power source. 2. Disconnect the red...
Page 19
Page 19 service (cont.) contactor assembly (cont.) p778 27040 032201 test procedures : electronic control (brewers w/recovery booster) 1. Disconnect the brewer from the power source. 2. Disconnect the gray wire from the black wire on the rear of the contactor coil and white /brown wire from the blac...
Page 20
Page 20 b.) 200 to 240 volts ac for two wire 200 or 240 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 brewer wiring harness. 5. Locate the black wires from...
Page 21
Page 21 p780 service (cont.) 27040 032201 removal and replacement: 1. Remove wires from the control thermostat. 2. Remove the thermostat capillary bulb by firmly pulling up on the capillary tube at the tank lid. This will disengage the grommet from the tank lid. 3. Remove the #8-32 slotted head scre...
Page 22
Page 22 . Mi nu te s bu nn -o- ma tic p/ n 26 20 - 1 20 v ac . Min ute s bu nn -o-ma tic p/ n 26 20 - 1 20 va c st art on / w arm er sel ec to r re ad y re ad y on / w arm er st art 1 1⁄2 ga l 1 g al 1⁄2 ga l sel ec to r 1 1⁄2 ga l 1 g al 1⁄2 ga l p782 dispense valve p796 location: dispense valves a...
Page 23
Page 23 service (cont.) location: the electronic control assembly (1) is located inside the lower left front on the component bracket of the brewer. Access will also be needed to the tempera- ture sensor (8), liquid level probe (7) located on the tank lid and to the triac assembly (17) located benea...
Page 24
Page 24 service (cont.) problem: liquid level control system does not refill problem: liquid level control overflows retry no yes yes no yes replace control assembly (1) drain cup (4) overflow ? Overflow ? No overflow ? Replace solenoid valve (14) drain cup (4) disconnect wire solenoid valve (14) fr...
Page 25
Page 25 yes yes yes yes no no no no yes no no measure voltage at tank heater (5) voltage present replace tank heater (5) limit thermostat (6) ok ? Replace limit thermostat (6) replace control assembly (1) measure voltage at tank heater (5) voltage present replace triac (17) check for split tank heat...
Page 26
Page 26 service (cont.) electronic controls (cont.) problem: water boils yes no no no no replace control assembly (1) replace triac (17) check for split tank heater (5) drain cup (4) retry led (13)(15) on while boiling disconnect blue wire from control board pin #7 retry still boiling ? Replace cont...
Page 27
Page 27 service (cont.) electronic control assembly (cont.) o n caution ! Failure to comply voids warrant y! Hot water systems – water tank will f ill automatically whe n unit is connect ed to po wer! Coffee brewers – fill the water tank in accordance w ith t he install ation instructions! Do not tu...
Page 28
Page 28 p787 service (cont.) electronic control assembly (cont.) 11. Install new triac/heat sink assembly on right tank mounting bracket. 12. Route the wires up around the rear of the brewer. 13. Reinstall the bottom cover, four feet, tank mount- ing brackets and triac/heat sink to the bottom of the...
Page 29
Page 29 ! Ca ut io n ho t w at er . Min ut es bu nn- o- ma tic p/ n 26 20 - 12 0 v ac . Min ut es bu nn -o- ma tic p/ n 26 20 - 12 0 v ac sta rt on / w ar mer sel ecto r re ady ready on / wa rm er sta rt 1 1⁄2 gal 1 g al 1⁄2 gal sel ecto r 1 1⁄2 gal 1 gal 1⁄2 gal c a u t i o n : w a r m e r s a n d ...
Page 30
Page 30 service (cont.) level control board and level probe (electro/ mechanical only) (cont.) 15. Move the probe's flat end to the brewer housing. The indication must be 0. 16. Move the probe's flat end away from the brewer housing. The indication should again be: a.) 120 volts ac for three wire 12...
Page 31
Page 31 service (cont.) if voltage is present as described, reconnect the black wire to the limit thermostat from the terminal block, the limit thermostat is operating properly. If voltage is not present as described, refer to the wiring diagrams and check brewer wiring harness. Removal and replacem...
Page 32
Page 32 service (cont.) location: the on/off switches are located on the front of the hood just to the left and right of the start switches. Test procedure: 1. Disconnect the brewer from the power source. 2. Viewing the switch from the back remove the white or red wire from the upper right terminal ...
Page 33
Page 33 location: the overflow protection switch is located inside the hood on the center of the tank inside the copper overflow cup. To test the overflow protection switch, access will also be needed to the level control board or electronic control assembly and terminal block. Test procedure: 1. Di...
Page 34
Page 34 ! Ca ut io n ho t w at er . Mi nu te s bu nn -o- ma tic p/ n 26 20 - 12 0 v ac . Mi nu te s bu nn- o- ma tic p/ n 26 20 - 12 0 v ac st art on / w arm er sel ec to r re ad y re ad y on / wa rm er st art 1 1⁄2 ga l 1 g al 1⁄2 gal sel ec to r 1 1⁄2 ga l 1 g al 1⁄2 ga l c a u t i o n : w a r m e...
Page 35
Page 35 red blk to blk lead on contactor coil blk to blk lead on thermostat whi/red to left dispense valve whi/brn to left dispense valve whi/grn to right dispense valve blu to blu lead from thermostat blu to blu lead from liquid level board whi/vio to right dispense valve right left gry to blk lead...
Page 36
Page 36 service (cont.) solenoid valve (inlet) ! Ca ut io n ho t w at er . Mi nu te s bu nn -o-ma tic p/ n 26 20 - 1 20 v ac . Mi nu te s bu nn -o-ma tic p/ n 26 20 - 1 20 va c sta rt re ady on / wa rm er sta rt sel ect or 1 1⁄2 ga l 1 g al 1⁄2 ga l c a u t i o n : w a r m e r s a n d s u r f a c e ...
Page 37
Page 37 st ar t on / w ar me r sel ec to r read y read y on / w ar me r st ar t 1 1⁄2 ga l 1 g al 1⁄2 ga l sel ec to r 1 1⁄2 ga l 1 g al 1⁄2 ga l p792 start switches location: the momentary start switches are located in front of hood just left and right of center. Test procedure: 1. Disconnect the b...
Page 38
Page 38 tank heater(s). Note - if the tank heater remains unable to heat, remove and inspect the heater for cracks in the sheath. Electronic models: 1. Disconnect the brewer from the power source. 2. Disconnect wires from heater(s). 3. Check for continuity across the tank heater termi- nals. If cont...
Page 39
Page 39 location: the timers are located inside the left front of the brewer on the upper part of the component bracket. Test procedures: 1. Disconnect the brewer from the power source. 2. Disconnect the wires from the timer terminals tl3, tl4 and tl5 and rotate the dial(s) fully counterclockwise. 3...
Page 40
Page 40 . Minutes bunn-o-matic p/n 2620- 120 vac . Minutes bunn-o-matic p/n 2620- 120 vac whi/vio tl1 to right on/off switch whi/vio tl1 to right warmer element whi/red tl1 to left on/off switch whi/red tl1 to left warmer element ora tl3 to left start switch whi/brn tl4 to left dispense valve yel tl...
Page 41
Page 41 service (cont.) timers (early models)(cont.) p847 . Min ut es bun n-o -m at ic p/n 2620- 120 v ac . Min ute s bu nn-o -m atic p/n 2620- 120 va c whi/vio tl1 to right on/off switch whi/vio tl1 to right warmer element whi/red tl1 to left on/off switch whi/red tl1 to left warmer element ora tl3...
Page 42
Page 42 27040 032201 service (cont.) timers (late models) p2194 location: the timers are located inside the left front of the brewer on the upper part of the component bracket. Test procedure. Note: do not remove or install wires while timer board is installed. Pressure applied to one side may cause...
Page 43
Page 43 27040 032201 p2037 service (cont.) timers (late models)(cont.) left timer right timer yel whi/yel wire to tl5 whi/brn whi/grn wire to tl4 ora whi/ora wire to tl3 whi whi wire to tl2 (120v two pole, 120/208v or 120/240v three pole terminal block) red red wire to tl2 (200v or 240v two pole ter...
Page 44
Page 44 service (cont.) warmer elements whi/vio to right timer tl1 whi to terminal block (white insert on three pole terminal blocks or red insert on two pole terminal blocks) whi or red to left warmer element right warmer element left warmer element whi to terminal block (white insert on three pole...
Page 45: (W/two-Grinder Interface)
Page 45 120/208 volts ac or 120/240 volts ac 3 wire r t s e l e c t o r s w vio probe pin-20 1 4 3 2 liquid level board blu blk k1 whi limit thermostat sol whi whi overflow protection sw red red sw. & thermostat ready indicators optional recovery booster blk blu k2 n.O. K3 n.O. Red schematic wiring ...
Page 46: (W/two-Grinder Interface)
Page 46 r t s e l e c t o r s w vio probe pin-20 1 4 3 2 liquid level board blu k1 red sol red red sw. & thermostat ready indicators optional recovery booster blk blu k2 n.O. K3 n.O. Red schematic wiring diagram dual-a & -b brewer (w/two-grinder interface) grn/yel red-12 k1 n.O. Blu tank heaters (tw...
Page 47: (W/two-Grinder Interface)
Page 47 blk-12 blu-12 schematic wiring diagram dual brewer eca (w/two-grinder interface) r t s e l e c t o r s w whi whi/ora whi/vio whi/grn whi/yel whi whi/red whi/grn l1 n tank heaters (two) blk 1 right brew timer 3 2 4 5 1/4 batch 1/3 batch 1/2 batch 2/3 batch 3/4 batch batch common fractional ba...
Page 48: (W/two-Grinder Interface)
Page 48 schematic wiring diagram dual-a & -b brewer eca (w/two-grinder interface) r t s e l e c t o r s w red whi/ora whi/vio whi/grn whi/yel red whi/red whi/grn l1 grn/yel tank heaters (two) blk 1 right brew timer 3 2 4 5 1/4 batch 1/3 batch 1/2 batch 2/3 batch 3/4 batch batch common fractional bat...
Page 49: (W/one-Grinder Interface)
Page 49 120/208 volts ac or 120/240 volts ac 3 wire r t s e l e c t o r s w vio probe pin-20 1 4 3 2 liquid level board blu blk k1 whi limit thermostat sol whi whi overflow protection sw red red sw. & thermostat ready indicators optional recovery booster blk blu k2 n.O. K3 n.O. Red schematic wiring ...
Page 50: (W/one-Grinder Interface)
Page 50 blk-12 blu-12 schematic wiring diagram dual brewer eca (w/one-grinder interface) r t s e l e c t o r s w whi whi/ora whi/vio whi/grn whi/yel whi whi/red whi/grn l1 n tank heaters (two) blk 1 right brew timer 3 2 4 5 1/4 batch 1/3 batch 1/2 batch 2/3 batch 3/4 batch batch common fractional ba...
Page 51: (W/one-Grinder Interface)
Page 51 r t s e l e c t o r s w vio probe pin-20 1 4 3 2 liquid level board blu k1 red sol red red sw. & thermostat ready indicators optional recovery booster blk blu k2 n.O. K3 n.O. Red schematic wiring diagram dual-a & -b brewer (w/one-grinder interface) grn/yel red-12 k1 n.O. Blu tank heaters (tw...
Page 52: (W/one-Grinder Interface)
Page 52 schematic wiring diagram dual-a & -b brewer eca (w/one-grinder interface) r t s e l e c t o r s w red whi/ora whi/vio whi/grn whi/yel red whi/red whi/grn l1 grn/yel tank heaters (two) blk 1 right brew timer 3 2 4 5 1/4 batch 1/3 batch 1/2 batch 2/3 batch 3/4 batch batch common fractional bat...
Page 53: Schematic Wiring Diagram
Page 53 whi/grn whi/grn whi/red whi/red rt start sw blk blk lt start sw blk grn blk yel blk red blk pnk tan gry whi whi red red gry pnk pnk red whi pnk red ora yel vio blu whi/red whi/red whi whi whi blk tan blu whi/blu 10864.0000h 9/00 © 1995 bunn-o-matic corporation whi refill red blk red whi pnk ...