SYMPTOM
Boiler is cold.
L7148F Aquastat Control malfunction when used with vent damper. L7148F Aquastat Control in reset mode.
L7148F Aquastat Control high limit switch shuts off the boiler before the water temperature reaches the high limit setting.
Boiler is too hot
POSSIBLE CAUSE
No Power.
Defective Thermostat or thermostat wiring.
Defective transformer.
Defective Ignition module.
Vent damper is not connected.
L7148F Aquastat Control detects an error.
Incorrect sensor location.
L7148F Aquastat Control temperature setting is below the desired
temperature. Defective sensor.
Defective L7148F Aquastat Control. Incorrect temperature setting.
Sensor not fully inserted into well.
Defective L7148F Aquastat Control.
ACTION
Check for 120V at LIX, L2X
Check all wiring and cable connections.
Check the circuit breaker or fuse and, if necessary r reset or replace.
Short the W, R terminals on the L7148F Aquastat Control. If the system starts, check the thermostat and low voltage wiring.
Check for 24V at R, C. If no voltage, replace the transformer.
Check for 24V at the ignition system and vent damper and check all wiring connections. If voltage is present at the ignition system, replace the ignition system. If no voltage is present at the ignition system, but 24V is present at the vent damper, replace the vent damper.
Verify proper connection at the vent damper and L7148F Aquastat control. Verify proper Sensor connections at the immersion well and L7148F Aquastat Control.
Check if the boiler water temperature is below the limit setting.
NOTE: The L7148F Aquastat Control may remain in reset mode 30 minutes after the error condition is corrected. To reset immediately, remove power,
and then restore power. Follow the boiler manufacturer
recommendations for proper location. Reset the potentiometer to the correct temperature.
Check for shorted or open sensor and/or leads.
Temporarily replace existing sensor with new sensor. If system starts, replace the sensor.
Replace the L7148F Aquastat Control.
Adjust the potentiometer to the proper temperature setting.
Reinsert the sensor fully into the well. Replace the L7148F Aquastat Control.
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