HVACopediaLennox · Furnace
E115 Low 24 VAC
What the control is telling you
Control voltage is below range (normal range 18 to 30 volts). The control restarts once voltage recovers.
Applies to: EL296UHV(X) series furnaces (integrated control 103130-XX and 107045-XX)
Likely causes
- Overloaded transformer from power-robbing accessories
- Undersized transformer
- Low line voltage
Test and repair steps
- Measure 24 VAC at the control; it should be between 18 and 30 volts.
- Check line voltage feeding the transformer.
- Look for extra accessories drawing from the 24 V circuit.
- Check the 3 A 24 V circuit breaker in the control box.
- Install a larger VA transformer if the load is too high; code clears when voltage recovers.
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 ML180UHE
- 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.33; Ignition Control 107045-XX Diagnostic Codes table, p.40. Summarized in our own words; check the original manual for your model.
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