By Barry Stone
Dear Barry,
My home has a forced-air heating system. Whenever I turn off the thermostat, the airflow doesn't turn off right away but continues to blow for several minutes. Is this a problem? If so, whom should I call, a heating contractor or the gas company? - Sheila
Dear Sheila,
The conditions you describe sound normal. If you had written to say that your forced-air system shut down immediately after turning off the thermostat, I would have recommended calling a heating (HVAC) contractor.
When you turn on your thermostat, the burner in your furnace ignites, but the blower does not begin to operate until the interior of the furnace becomes sufficiently heated - usually to about 150 degrees. When the thermostat is turned off, the flame goes out at the burner, but the blower stays on until the inside of the furnace is sufficiently cooled. This helps to prolong the longevity of internal components.
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