68-0189—2 G.R. Rev. 10-01
www.honeywell.com
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Home and Building Control Home and Building Control
Honeywell International
Honeywell Europe
S.A. Honeywell Latin American
Honeywell
Honeywell Limited-Honeywell Limitée Home and Building Control
3 Avenue du Bourget
Region
1985 Douglas Drive North
35 Dynamic Drive
Honeywell Building
1140 Brussels
480 Sawgrass Corporate Parkway
Golden Valley, MN 55422
Scarborough, Ontario
17 Changi Business Park Central 1
Belgium
Suite 200
M1V 4Z9
Singapore 486073
Sunrise FL 33325
L7148F ELECTRONIC AQUASTAT
®
CONTROLLER
Fig. 12. L7148F troubleshooting flowchart.
START
BOILER IS COLD.
BOILER IS NOT REACHING PROPER
TEMPERATURE OR WILL NOT TURN ON.
CHECK: L7148F DIAGNOSTIC LED ON?
CHECK FOR 120 VAC AT L1X, L2X.
CHECK FOR 24 VAC AT R, C.
TURN POWER ON;
CHECK ALL WIRING CONNECTIONS;
REPLACE TRANSFORMER AS APPROPRIATE.
SET ROOM THERMOSTAT AT 10 DEGREES
ABOVE ROOM TEMPERATURE.
SET BOILER 10 DEGREES (OR MORE)
ABOVE CURRENT WATER TEMPERATURE.
BOILER TURNS ON?
SHORT TERMINALS W-R (T-TW) ON L7148F.
BOILER STARTS?
THERMOSTAT OR THERMOSTAT WIRING
PROBLEM. CHECK SYSTEM PER
INSTRUCTIONS PROVIDED WITH THERMOSTAT.
NO
NO
YES
NO
YES
CHECK: L7148F DIAGNOSTIC LED FLASHING?
TWO BLINKS:
CHECK SENSOR CONNECTIONS.
IF GOOD, REPLACE SENSOR.
THREE OR FOUR BLINKS:
INTERNAL ERROR, REPLACE L7148F.
L7148F IN RESET MODE (WAIT FIVE
MINUTES FOR CONTROL TO RESET).
VENT DAMPER OPEN?
CHECK FOR 24V AT B1, B2.
YES
CHECK VENT DAMPER
CABLE AND
CONNECTIONS.
REPLACE VENT
DAMPER CABLE OR
DAMPER AS
APPROPRIATE.
L7148F IS OKAY.
CHECK IGNITION AND
GAS VALVE SYSTEM
AS DESCRIBED
IN LITERATURE
PROVIDED WITH
THOSE PRODUCTS.
NO
YES
CHECK: CIRCULATOR PUMP RUNNING?
YES
120 VAC AT C1, C2?
ROOM THERMOSTAT STILL SET
10 DEGREES ABOVE CURRENT
ROOM TEMPERATURE?
NO
BOILER SHUTS OFF AT
HIGH LIMIT SETTING?
YES
NO
RESET THERMOSTAT AND
REPEAT VOLTAGE CHECK.
REPLACE
L7148F.
L7148F IS OKAY. CHECK OTHER SYSTEM
COMPONENTS: CIRCULATOR. ZONE VALVES.
YES
YES
NO
BOILER SHUTS OFF ABOVE
HIGH LIMIT SETTING?
NO
TRIADICATOR ACCURACY.
SENSOR FULLY INSERTED INTO WELL.
THERMO WELL IN GOOD CONDITION.
THERMO WELL LOCATED PER
BOILER OEM INSTRUCTIONS.
YES
CHECK:
L7148F DIAGNOSTIC LED FLASHING?
NO
(BELOW HIGH LIMIT)
TWO BLINKS: REPLACE SENSOR.
THREE OR FOUR BLINKS: REPLACE L7148F.
YES
TRIADICATOR ACCURACY.
THERMO WELL LOCATED PER
BOILER OEM INSTRUCTIONS.
NO
M20069
YES
NO
CHECK:
CHECK:
CHECK:
CHECK:
