Honeywell L8104A, L8104D, L8104B, L8104C User Manual
L8104A,B,C,D
68-0063-3
Electronic Water
Heater Controllers
The L8104A,B,C,D Electronic Controllers provide temperature control and ECO limit action for
gas water heaters.
■ L8104A,B are used in standing pilot and electronic
ignition systems.
■ L8104C,D are used only in electronic ignition sys-
tems.
■ Includes electronic module, one or two sensing bulbs,
and setpoint potentiometer (remote- or boardmounted).
■ Sensing bulb contains thermistor sensor and ECO
switch. Second bulb in L8104B,C contains thermistor only.
■ L8104A has single sensing bulb.
■ L8104B has two sensing bulbs available with upper
and lower bulb sensing authority allocated in ratios
of 1:1, 2:1, 3:1, and 4:1. Two sensing bulbs provide
temperature averaging.
■ L8104C has two sensing bulbs and manual reset
pushbutton.
■ L8104D has one sensing bulb and manual reset
pushbutton.
L8104B with
Potentiometer
Remote
Potentiometer
Sensing
Bulb
■ Temperature range is factory-set to meet application
requirements. Maximum setting temperature is 200°F
(93°C).
■ ECO limit setting is factory-set to meet application
requirements.
■ For L8104A,B, standing pilot must be manually re-
lit or ignition module must be reset when ECO shuts
off gas control.
■ For L8104C,D, ignition module must be reset using
pushbutton switch mounted on electronic control
module when ECO shuts off gas control.
■ Control circuit is accurate within ±3.5°F (1.9°C) at
maximum setpoint (200°F [93°C]; setpoint controls
are accurate within +7°F [+3.8°C], -0°F [-0°C]).
CONTENTS
Specifications ................................................. 2
Ordering Information ..................................... 2
Installation ..................................................... 5
Setting and Checkout.................................... 10
Operation ..................................................... 11
Troubleshooting ........................................... 12
Material Safety Data Sheets ......................... 15
J. H. • Rev. 6-95 • ©Honeywell Inc. 1995
1 68-0063—3
L8104A,B,C,D
SPECIFICATIONS • ORDERING INFORMATION
Specifications
IMPORTANT: The specifications given in this publication
do not include normal manufacturing tolerances.
Therefore, this unit may not exactly match the listed
specifications. Also, this product is tested and calibrated under closely controlled conditions, and some
minor differences in performance can be expected if
those conditions are changed.
MODELS:
L8104A Electronic Commercial Water Heater Control-
ler: Includes electronic control module, single sensing
bulb containing thermistor and ECO switch, and remote- or board-mounted potentiometer.
L8104B Electronic Commercial Water Heater Control-
ler: Includes electronic control module, two sensing
bulbs (one with thermistor and ECO switch and one
with thermistor only), and remote- or board-mounted
potentiometer. Models are available with sensing authority allocated between the upper and lower sensing
bulbs in ratios of 1:1, 2:1, 3:1 and 4:1; specify when
ordering.
L8104C Electronic Commercial Water Heater Control-
ler: Same as the L8104B with additional circuitry to
manually reset the ECO switch.
L8104D Electronic Commercial Water Heater Control-
ler: Same as the L8104A with additional circuitry to
manually reset the ECO switch.
ELECTRICAL RATINGS:
Power Supply: 24 Vac, 50/60 Hz.
Gas Control Relay Contacts:
Inductive: 2A full load, 10A locked rotor.
Resistive: 2A.
TEMPERATURE SETTING RANGE: Temperature range
factory set to meet application requirements. Maximum
setting temperature is 200°F (93°C). Specify desired
range when ordering.
DIFFERENTIAL: Factory set from 2 ± 0.5°F (1 ± 0.3°C) to
15 ± 4.5°F (8 ± 2.5°C). Specify when ordering.
AMBIENT TEMPERATURE RANGE AT MODULE: 0°F
to +175°F (-18°C to +80°C).
ECO LIMIT SWITCH: Recycling or nonrecycling (one-
shot). Sensing bulb must be replaced if nonrecycling ECO
switch opens. Cutout temperature is factory set to meet
application requirements. Specify type and desired cutout
temperature when ordering. Recycling ECO is used on
manual reset models (L8104C,D).
POTENTIOMETER:
Remote: Minimum setting is at fully counterclockwise
rotation. Has 12 in. (30 cm) leadwires on terminals 1 and 2 and factory-mounted jumper across
terminals 2 and 3. Specify when ordering L8104.
Board-mounted: Setting scaleplate provided. Specify range
and board mounting when ordering L8104.
SENSING BULB: Bulbs available in several styles and
materials with various leadwire lengths. Thermistor sensor and ECO limit are factory-mounted in bulb; leads
terminate with 1/4 in. quick connects. Second bulb on
L8104B contains only thermistor sensor; leads terminate
with 3/16 in. quick connects.
MOUNTING:
Electronic Control Module: Mounts on enclosed panel
with four no. 6 or 8 screws (obtained locally) through
standoffs on module corners. Can be mounted in locations that reach up to 95 percent relative humidity
(noncondensing), but avoid locations where water
may drip on module.
Sensing Bulbs: Can be mounted in immersion well or
directly immersed if properly sealed to prevent leakage. Well or seal must be ordered separately.
Setpoint Potentiometer: Remote potentiometer mounts
through panel with nut on threaded shaft.
Ordering Information
When purchasing replacement and modernization products from your TRADELINE® wholesaler or your distributor, refer to the Tradeline
Catalog or price sheets for complete ordering number, or specify—
1. Order number. 6. Potentiometer mounted on electronic module or remote unit.
2. Temperature setting range desired. 7. Setting scale for board-mounted potentiometer.
3. Differential setting desired. 8. Sensing authority desired (L8104B,C only).
4. ECO cutout temperature desired. 9. Sensing bulb: Specify style, material, and lead wire length.
5. Recycling or nonrecycling ECO switch. 10. Additional system components, if desired.
If you have additional questions, need further information, or would like to comment on our products or services, please write or phone:
1. Your local Honeywell Home and Building Control Sales Office (please check the white pages of your phone directory).
2. Home and Building Control Customer Logistics
Honeywell Inc., 1885 Douglas Drive North
Minneapolis, Minnesota 55422-4386
In Canada—Honeywell Limited/Honeywell Limitée, 35 Dynamic Drive, Scarborough, Ontario M1V 4Z9. International Sales and
Service Offices in all principal cities of the world. Manufacturing in Australia, Canada, Finland, France, Germany, Japan, Mexico,
Netherlands, Spain, Taiwan, United Kingdom, U.S.A.
68-0063—3 2
L8104A,B,C,D
SPECIFICATIONS
DIMENSIONS:
L8104: Fig. 1.
L8104A,B: Fig. 2.
L8104C,D: Fig. 3.
available through your Honeywell sales representative.
Please provide the ordering information indicated in the
Ordering Information section to assure correct replacement components.
APPROVALS:
Underwriters Laboratories Inc. Component Recognized:
File No. MP466, Guide No. MBPR2.
American Gas Association Certified: Report No. 70-22A.
Fig. 1—Approximate dimensions in in. (mm) of
L8104 Remote Potentiometer and Sensing Bulb.
Canadian Gas Association Certified: Report No. 1029-
CC/T-6849.
OTHER SYSTEM COMPONENTS (Order separately):
Electronic
REMOTE MOUNT POTENTIOMETER
3/4
3/8
(10)
(19)
3/8 DIA.
(10)
5/32
(4)
Ignition
System
Standing
pilot
Intermittent
pilot
Module Gas Control
— VR800, VR8200, or any
rated 2.0A or less
S86F,H;
S8600H;
VR8440, VR8204 or
any rated 2.0A or less
1-1/4 (32)
3/8
(10)
S8610F,H
12 IN. (305 MM)
REPLACEMENT PARTS: Replacement electronic control
LEADWIRES
modules, sensing bulbs, and remote potentiometers are
Fig. 2—Approximate dimensions in in. (mm) of L8104A,B Electronic Control Module.
FACTORY
INSTALLED
JUMPER
15/16
(24)
1-1/16
1-3/8
(27)
(35)
1
3
2
TERMINALS
1, 2 & 3
M413
1/4
(6)
(TWO)
.170 DIA.
(FOUR)
L8104A,B ELECTRONIC CONTROL MODULE
2-15/32 (63)
1-15/16 (49)
3/4 (19)
120
100
4
2
UPPER
4
SEN-2
COM.
3
RELAY
NO
3
1
MODELS WITH REMOTE POTENTIOMETER HAVE TWO 1/4 IN.
TAB TERMINALS IN PLACE OF THE POTENTIOMETER.
2
L8104A DOES NOT HAVE UPPER OR SEN-2 TERMINALS.
1/4 IN. TAB TERMINALS (3)
3
4
3/16 IN. TAB TERMINALS (5)
140
180
1
160
4
4
4
3
SEN-1
LOWER
24 V
HOT
ONLY
1/4
(6)
(TWO)
2-15/16
(75)
3-15/32
(88)
1/2
(13)
3/8
(10)
1-1/8 (29) 9/32
1
1 (25)
M113C
(7)
3 68-0063—3
L8104A,B,C,D
SPECIFICATIONS
ACCESSORIES:
L8104A:
4074ENP Potentiometer Assembly: 199075A Poten-
tiometer: Clockwise turn increases temperature,
two 18 in. [46 cm] leadwires with 1/4 in. quick
connects. Washer and nut.
4074ENS Potentiometer Assembly: 199053A Potenti-
ometer: Counterclockwise turn increases temperature, two 18 in. (46 cm) leadwires with one bare wire
and one 1/4 in. quick connect. Washer and nut.
198800A One-Shot Sensor Assembly (nonrecyclying):
189°F (87°C) cutoff temperature. 11 in. (28 cm)
sensor and ECO leadwires. Sensor leadwire is 1/4
in. quick connect. ECO leadwire is stripped.
198800B One-Shot Sensor Assembly (non recycling):
200°F (93°C) cutoff temperature. 11 in. (28 cm)
sensor and ECO leadwires. Sensor leadwire is 1/4
in. quick connect. ECO leadwire is stripped.
198799B Sensor Assembly: 42 in. (107 cm) 150°C
(302°F) leadwires with 1/4 in. quick connects.
L8104B:
198799A Sensor Assembly: 42 in. (107 cm) 125°C
(257°F) leadwires with 1/4 in. quick connects.
198799B Sensor Assembly: 42 in. (107 cm) 150°C
(302°F) leadwires with 1/4 in. quick connects.
198799C Sensor Assembly: 42 in. (107 cm) 105°C
(221°F) leadwires with 1/4 in. quick connects.
198799D Sensor Assembly: 42 in. (107 cm) 105°C
(221°F) leadwires with 1/4 in. quick connects.
200636A Sensor Assembly: 180° F to 201°F (83°C to
94°C) cutoff temperature. 22 in. (56 cm) 150°C
(302°F) leadwires.
200636B Sensor Assembly: 180°F to 201°F (83°C to
94°C) cutoff temperature. 22 in. (56 cm) 150°C
(302°F) leadwires.
200636C Sensor Assembly: 180°F to 201°F (83°C to
94°C) cutoff temperature. 22 in. (56 cm) 150°C
(302°F) leadwires.
200650A Potentiometer: Clockwise turn increases tem-
perature. 8 in. (20 cm) leadwires with two 1/4 in.
quick connects.
Fig. 3—Approximate dimensions in in. (mm) of L8104C,D Electronic Control Module.
2-7/16 (62)
(TWO)
3/16 IN. TAB
TERMINALS
1/4
(6)
1 (25)
1-61/64 (50)
140
120
100
180
1
160
1/4
(6)
(TWO)
1/2
(13)
19/32
(15)
1-1/8 (29) 9/32
1
(7)
.170 DIA. (FOUR)
1/4 IN.TAB
TERMINALS
LOCKOUT
INDICATOR
LIGHT
C1
K2
VALVE
SEN-1
LOWER
COM.
24V
PV
ECO
ECO
2-61/64
(75)
(TWO)
UPPER
SEN-2
U1
K1
LOAD
PUSH BUTTON RESET
1 MODELS WITH REMOTE POTENTIOMETER HAVE TWO
1/4 IN. TAB TERMINALS IN PLACE OF THE POTENTIOMETER.
4-23/64
(111)
1 (25)
M414
68-0063—3 4
L8104A,B,C,D
L8104A, D
L8104B, C
ELECTRONIC
CONTROL
MODULE
ENCLOSURE
SENSING
BULB
(WITH ECO)
THERMOCOUPLE
AND PILOT
BURNER
MAIN
BURNER
UPPER
SENSING BULB
(WITHOUT ECO)
THERMOCOUPLE
AND PILOT BURNER
MAIN
BURNER
LOWER
SENSING BULB
(WITH ECO)
ELECTRONIC
CONTROL
MODULE
ENCLOSURE
M132A
INSTALLATION
Installation
WHEN INSTALLING THIS PRODUCT…
1. Read these instructions carefully. Failure to follow
them could damage the product or cause a hazardous
condition.
2. Check the ratings given in the instructions and on
the product to make sure the product is suitable for your
application.
3. Installer must be a trained, experienced service
technician.
4. After installation is complete, check out product
operation as provided in these instructions.
WARNING
EXPLOSION HAZARD.
CAN CAUSE PROPERTY DAMAGE,
SEVERE INJURY OR DEATH.
This product is for use only in a system with a
pressure relief valve.
CAUTION
Disconnect power supply before wiring to prevent
electrical shock or equipment damage.
IMPORTANT: Do not bend or pull on sensor leadwires
when temperature is below freezing to prevent leadwire
damage. Install L8104 only when temperature is above
32°F (0°C).
LOCATION AND MOUNTING
Sensing Bulb(s)
The water heater manufacturer usually provides a tapping for the sensing bulb at a point where average water
temperature can be measured. With L8104B,C, the bulb
containing the thermistor and ECO switch is usually mounted
in the tapping near the bottom of the heater, and the other
bulb is located near the top. See Fig. 4. Follow the heater
manufacturer instructions.
The sensing bulb can be installed in an immersion well
or directly immersed with a suitable compression fitting to
prevent leakage. Wells and fittings must be ordered separately.
If an immersion well is used, the bulb should fit snugly
and should touch the bottom of the well for best temperature
response. Use heat-conductive compound (available in 4 oz
can as Honeywell part no. 107408) to fill the space between
the bulb and the well and improve heat transfer characteristics. Make sure the bulb is held firmly in the well.
If the sensor is directly immersed, use a 3/8 in. x 1/2 in.
compression to M.I.P. coupling or O-ring and clamp to
prevent leaks and keep bulb leadwires dry.
Electronic Control Module
Locate the electronic control module on a wall or panel
in the wiring compartment of the water heater. The module
must be within easy reach of the sensor leadwires in a
location that is convenient for reading and changing the
temperature setting. Choose a location where the module
will not be exposed to water. An enclosure is recommended
to help protect the module. Mount the module with four no.
6 or 8 screws through the corner standoffs.
Remote Mount Potentiometer
Choose a location that is convenient for reading and
changing the temperature setting. Mount the potentiometer
from the back of a panel through a 3/8 in. hole and secure it
with a nut on the threaded shaft.
WIRING
IMPORTANT: For maximum trouble free operation, run
the sensing bulb leadwires separately from any other
current-carrying wires.
All wiring must comply with local codes and ordinances. Disconnect power supply before beginning wiring.
Connect according to water heater manufacturer instructions, if available, or use Fig. 5 through 10 as a guide.
Fig. 4—Possible location of thermistor/ECO
bulb and thermistor bulb.
5 68-0063—3
L8104A,B,C,D
INSTALLATION
Fig. 5—L8104A with board-mounted potentiometer in a standing pilot application.
Q308
COM.
RELAY
NO
L8104A
1
4
0
120
160
100
180
2
2
3
3
LOWER
3
2
SEN-1
24V
HOT
ONLY
BLACK
BLACK
RED
RED
SENSING BULB WITH
ECO SWITCH
L1
(HOT)
L2
ECO
CONNECTOR
TH TR
1
24V
VR8200
GAS VLAVE
1
POWER SUPPLY. PROVIDE DISCONNECT
MEANS AND OVERLOAD PROTECTION
AS REQUIRED.
2
1/4 IN. TAB TERMINALS (3).
3/16 IN. TAB TERMINALS (3).
3
Fig. 6—L8104A with remote potentiometer in an electronic ignition application.
BLACK
1
2
3
3
SENSING BULB WITH
ECO SWITCH
RED
RED
PILOT
VALVE
1ST
OPERATOR
1
POWER SUPPLY. PROVIDE DISCONNECT
MEANS AND OVERLOAD PROTECTION
AS REQUIRED.
2
COM
2ND
OPERATOR
GAS CONTROL
VR844, VR8440
S8600F,H,M;
S8610F,H
MV MV/PV PV
GND
(BURNER)
L8104A
COM.
4 5
RELAY
NO
4
TH-W
24V
24V
(OPT)
GND
POT
VENT
DAMPER
PLUG (OPT)
4
5
SEN-1
5
LOWER
24V
HOT
ONLY
SPARK
BLACK
SETPOINT
POTENTIOMETER
(SHOWN FROM BACK)
MAIN
VALVE
VR8440 OR
VR844
2
TERMINAL DESIGNATIONS
PILOT COM MAIN
TH TH-TR TR
M131C
1
L1
(HOT)
L2
24V
68-0063—3 6
3
FACTORY INSTALLED JUMPER; DO NOT
REMOVE.
4
1/4 IN. TAB TERMINALS (3).
3/16 IN. TAB TERMINALS (3).
5
M128B
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