American Standard Underfiring or Low Heat Output

The furnace runs, but the house never reaches the set temperature, and the supply air feels lukewarm.

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

Low gas pressure, partially plugged burner orifices, incorrect manifold pressure setting, wrong orifice size installed on the American Standard furnace.

How to Fix / Troubleshooting

Safety: Gas pressure and burner adjustments must be done by a licensed technician.

Basic homeowner checks:
- Ensure the filter is clean and all registers are open.
- Verify the thermostat is not in setback mode.
Professional service:
- Have a technician measure inlet and manifold gas pressure.
- Clean burner orifices and verify the correct size per the rating plate.

Repair Difficulty

Professional Required 5/5

Required Part

Burner Orifices

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