Weil McLain F14

What does Weil McLain F14 mean?

F14 indicates the CH supply water temperature sensor 2 (the high limit sensor) has gone outside its valid operating range due to a short circuit or open circuit. All heat demands are disabled while the fault is active. The fault clears automatically when the sensor reading returns to a valid range.

Symptoms

• Boiler displays F14 and stops all heating.
• No central heating or domestic hot water while fault is active.
• Fault may clear briefly then return if wiring is intermittently faulted.
• May accompany F10 if both supply sensors fail simultaneously.

Common causes

• Supply sensor 2 (high limit NTC sensor) damaged or failed (open or short circuit).
• Sensor wiring shorted due to insulation wear or heat damage.
• Sensor wiring disconnected at the sensor or control board terminal.
• Corroded or improperly seated sensor connector on the control board.

Diagnostic steps

1. 01

   Locate supply sensor 2

   Find the secondary CH supply temperature sensor (high limit NTC) on the boiler discharge assembly. Refer to the AquaBalance Series 2 boiler manual component diagram for its exact position.

2. 02

   Inspect sensor wiring

   Trace the wiring from the sensor to the control board. Look for damaged insulation, pinching, or loose terminals. Repair any faults found.

3. 03

   Re-seat the connector

   Unplug and firmly re-insert the sensor connector at the control board. Inspect for corrosion. Reset the boiler and verify whether F14 clears.

4. 04

   Measure sensor resistance

   Disconnect the sensor and measure its resistance. Compare to the temperature-resistance table in the boiler manual. A short or open reading confirms sensor failure.

5. 05

   Replace the sensor

   Install the correct Weil-McLain replacement sensor. Restore power, reset the boiler, and confirm F14 does not return during a heating cycle.

When to call a professional

Call a licensed technician if F14 persists after sensor replacement, or if it appears simultaneously with F10 (supply sensor 1 fault). Multiple concurrent supply sensor faults on a properly wired boiler indicate a control board input circuit failure requiring board-level diagnosis and replacement with the correct Weil-McLain part number.