HVACopediaLennox · Furnace
E311 Heat rate reduced for airflow
What the control is telling you
Warning only: blower is in cutback due to restricted airflow, so firing rate is reduced every 60 seconds to match available CFM (2-stage controls drop to 1st stage).
Applies to: EL296UHV(X) series furnaces (integrated control 103130-XX and 107045-XX)
Likely causes
- Dirty filter
- Undersized or restricted ductwork
Test and repair steps
- Check and replace the filter if dirty.
- Inspect the duct system for restrictions; repair or add duct as needed.
- Clears when a heat call completes successfully.
Settings for these units
- Recommended filter size by cabinet width · EL296UHV
- Recommended filter size by cabinet width · Lennox SL280UHV
- Filter sizes by cabinet width · Lennox SL297NV
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Source: Lennox EL296UHV(X) Unit Information / Service Literature, Table 5 Ignition Control 103130-XX Diagnostic Codes, p.36; Ignition Control 107045-XX Diagnostic Codes table, p.43. Summarized in our own words; check the original manual for your model.
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