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Stale/stuffy, fatigue, headaches

What is going on

Possible causes and checks for: stale/stuffy, fatigue, headaches.

Likely causes

  • Poor ventilation (high CO₂ marker)
  • Tight envelope
  • Dirty filters

Check in this order

  1. Add HRV/ERV or damper-controlled fresh-air duct
  2. Verify
  3. Cfm/person or 3+ ACH
  4. Replace filters

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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.