Problem Center · Boilers
Why Is My Boiler Not Heating?
No heat, or some radiators and zones stay cold.
What could cause this?
- No call for heat — thermostat, wiring or zone control
- Ignition or burner faults
- Circulator pump or zone valve failure
- Low water pressure or air in the system
- Steam system water level or control problems
- Error code lockout
What you can safely check
- Confirm thermostats are set to Heat and above room temperature
- Make sure the boiler service switch is on
- Note the pressure gauge reading and any error code on the display
- Note which zones or rooms are cold
Don't open electrical panels or equipment cabinets, handle refrigerant, work on gas or combustion components, or bypass safety controls.
When it requires a professional
If you smell gas, leave the building and call your gas utility or 911 from outside. Don’t reset a boiler repeatedly, add water to a steam boiler if you’re unsure how, or bypass controls. Request service with the gauge reading and any codes.
How Air Mechanical diagnoses it
We trace the call for heat from thermostat to burner, then check water flow, pressure, controls and venting. Cold zones and no heat at all point to different causes.
Every diagnosis starts with the system as it actually exists — equipment, controls, wiring and installation. The equipment has a brand. The problem has a solution.