By: Barry Stone
Dear Barry,
Our home has a 20-year old furnace which works fine in all respects except one. When the blower is on, the rush of air at the intake grills is terribly loud. According to our home inspector, the blower velocity can be changed from high to low speed by simply changing some wires. But I'm wondering if there are any negative side effects to this solution. - Ron
Dear Ron,
The high speed setting on a furnace blower is generally intended for air conditioning purposes. When the system is operating in heat mode, slower air circulation is recommended. Therefore, it is unlikely that you will experience any adverse consequences if you lower the blower speed of your forced air system.
If you check the manufacturer's rating plate on your furnace, you will observe a listing of temperature ranges for each speed setting. For low blower speeds, the range is usually between 40 and 70 degrees Fahrenheit. This means that the temperature of the heated air blowing from the room registers should be 40 to 70 degrees hotter than the air that is drawn through the intake grill. This is something you can check with a thermometer.
But be sure to have the system checked by a licensed heating contractor before proceeding with any changes.
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