Furnace runs but does not produce enough heat; home never reaches set temperature.
Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
Possible Causes
How to Fix / Troubleshooting
Safety first: Do not attempt to adjust gas pressure yourself. Gas adjustments must be done by a licensed technician.
Homeowner checks:
- 1. Replace air filter: A restricted filter can reduce airflow and heat transfer. Install a clean filter of the correct size and rating.
- 2. Open all vents: Ensure all supply registers and return grilles are open and unobstructed to allow full airflow.
- 3. Check thermostat calibration: Compare thermostat reading to a separate room thermometer. If off by several degrees, recalibrate or replace the thermostat.
- 4. Observe burner flames: With power on and a call for heat, check that all burners light fully and flames are blue and even. If some burners do not light or flames are small, call a professional.
When to call a professional: A technician should measure gas inlet and manifold pressure, clean burner orifices, and verify blower speed settings on the Philco control board.