Lennox · Air handler

E350 Electric heat not configured

High severity

What the control is telling you

Heat call with no electric heat configured, or configured incorrectly, on the air handler. S30/S40 thermostat alert code 350 (shown as E350 on the unit control display).

Applies to: Lennox communicating air handlers and EIM-equipped indoor units in S30/S40 smart thermostat systems

Likely causes

Electric heat stages not configured

Test and repair steps

Warning: Remove the smart hub/thermostat from the system before configuring electric heat.
Configure electric heat stages per the air handler installation instructions.
Clears after electric heat detection succeeds.

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Source: Lennox Residential Communicating Systems Alert Code Guide (V2) 100017 (3/2023), Table 2 Alert Codes and Troubleshooting, p.26. Summarized in our own words; check the original manual for your model.

Homeowner looking at this code? See what it means for you and when to call a technician.

For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.