Diagnose a chimney draft problem caused by stack effect, competing exhaust appliances, or inadequate makeup air

Steps

1. Interview the homeowner about when the draft problem occurs (only in certain weather, only when other appliances/fans run, only at startup) to narrow the likely cause before testing
2. Inspect the flue's height, size, and condition (via Level I/II inspection) to rule out an undersized, oversized, obstructed, or too-short flue as the root physical cause
3. Check for competing exhaust: test with kitchen exhaust fans, bathroom fans, clothes dryer, and other combustion appliances running to see if depressurization pulls draft away from the fireplace/chimney (backdrafting)
4. Assess the home's makeup air situation — tight, well-sealed homes are more prone to depressurization-driven draft reversal than leakier older homes
5. Consider stack-effect and temperature-related draft issues (cold flue, tall multi-story chimney runs, wind-exposed termination) and whether a warm-up/priming technique or termination change would help
6. Recommend the least invasive corrective measure first (makeup air provision, damper/cap adjustment, flue insulation) before recommending relining or height modification if simpler fixes resolve the symptom