HVACopediaAll brands · Boiler troubleshooting
Symptoms of air in system
What is going on
Pump motor failure / leak at packing, noisy wet-rotor pump (no lube), cavitation and turbulence noise, poor terminal-unit heat, accelerated corrosion.
Check in this order
- Bleed, purge, find source (bad vent, tight cap, painted vent, undersized venting, fresh-water ingress)
More boiler guides
Take it to the job
All guides, error codes and tips work offline in the HVACopedia app.
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.