Boiler: Poor heat / circulation
Poor heat / circulation on a boiler: Air-bound sections, cavitating pump, failed circulator, closed zone valve, waterlogged tank.
How to fix poor heat / circulation: step by step
- At operating temp supply−return ≥20 °F
- Bleed/purge
- Check vents, scoops
- Pump amp/noise
Safety: Gas, electrical and refrigerant work must be done by a licensed technician. Turn off power and gas before servicing, never bypass a safety control, and always follow the manufacturer's manual for your exact model.
If the unit shows an error code, look it up: Bosch Boiler codes Glow Brand Boiler codes Navien Boiler codes Rinnai Boiler codes Viessmann Boiler codes
Source: General HVAC service practice — verify per model. Written in our own words as a summary; always check the original manual.
General guidance for qualified technicians. The manufacturer's installation and service manual and local codes always take priority. Aurora Star Tech is not affiliated with, endorsed by or sponsored by any equipment manufacturer; brand and model names are used only to identify equipment and belong to their owners.