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Unsatisfactory heat (short cycles / uneven / not enough)

What is going on

Possible causes and checks for: unsatisfactory heat (short cycles / uneven / not enough).

Likely causes

  • Faulty thermostat
  • Faulty limit
  • Flame sensor low µA
  • Open auxiliary limit
  • Wrong heat-anticipator setting
  • Improper airflow/distribution
  • Bad thermostat location

Check in this order

  1. Test thermostat
  2. Test limit
  3. Test flame sensor
  4. Manual reset
  5. Check anticipator setting
  6. Check duct static (see A34)
  7. Relocate thermostat

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Source: General HVAC service practice — verify per model. Written in our own words; check the manual for your exact model.

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.