Thermostat displays E22 and indicates heat call output fault

Safety first: Turn off power to the furnace/air handler at the breaker before inspecting or changing wiring.

Steps to troubleshoot:

• 1. Check if heat operates: Raise the setpoint several degrees above room temperature and see if the furnace starts. If not, E22 is likely valid.
• 2. Inspect W wire at thermostat: Remove the thermostat and verify the W/W1 wire is secure and not touching other terminals.
• 3. Inspect W wire at furnace board: Confirm the same conductor is attached to the W/W1 terminal on the control board.
• 4. Check furnace fuse: Locate and inspect the low-voltage fuse on the control board. Replace if blown and look for shorts in the W circuit.
• 5. Test with jumper (advanced): With thermostat removed and power on, briefly jumper R to W at the furnace board. If the furnace starts, the thermostat W relay is suspect.
• 6. Replace thermostat if W relay is faulty: Internal relays are not serviceable; replace the Emerson thermostat.

When to call a professional: If the furnace does not respond even with a direct R–W jumper, contact an HVAC technician to diagnose the furnace control board and safety circuits.