HVACopediaAll brands · Furnace troubleshooting
Smoke, soot, odour, pulsation
What is going on
Possible causes and checks for: smoke, soot, odour, pulsation.
Likely causes
- Wrong oil pressure
- Flame impinging on chamber
- Not enough draft (dirty chimney/flue, regulator stuck/misadjusted, chamber or HX leak)
- Poor air-oil mixing (nozzle worn/loose/dirty/leaking, pressure wrong, poor turbulence, air shutter closed, fan binding, tight bearings)
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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.