Is On or Auto the Best Setting for Your Thermostat Fan

The best setting for your thermostat fan depends upon your energy efficiency, comfort and air quality goals, as well as the type of fan installed in your system. When it’s running, a residential blower fan moves over 1,000 cubic feet per minute of air. However, most thermostats have individual settings for the heat and air conditioning function and the fan. Homeowners have the option of “Automatic” setting or running the fan alone to circulate air. Here are some things to consider when deciding on the best setting for your thermostat fan.

Energy Efficiency

On “Automatic” setting, the fan runs only when the furnace or A/C is activated. System electrical consumption will be less than continuous fan operation. However, optional variable-speed electronically commutated motor (ECM) fan technology consumes much less power than the conventional permanent split capacitor (PSC) fan supplied as standard equipment on many older units. Because ECM fans run more efficiently in continuous mode than on/off PSC fans, energy savings from turning them off will be marginal.

Comfort Consistency

Running the thermostat fan continuously uniformly distributes conditioned air in living spaces. This is particularly helpful in heating season when hot air conveyed into rooms tends to rise naturally and accumulate at the ceiling when the blower fan turns off. If the fan is in continuous mode, circulating air constantly redistributes heating inside the room to keep occupants comfortable and reduces heat loss to the ceiling.

Air Quality

Household air is cleaned by the system filter only when it’s circulated through the ducts by the blower fan. When the fan cycles off in “Automatic” mode, air filtration also ceases. Continuous fan operation constantly refreshes indoor air. However, running the fan at all times also means more frequent filter changes.

At Sobieski Services, Inc., our goal is to help our customers in Delaware, Pennsylvania, Maryland and New Jersey learn more about energy and home comfort issues – especially HVAC and plumbing issues – so that they can save money and live in healthier, more comfortable homes.

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