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Bayonet Plumbing, Heating & Air Conditioning Blog

Thermostat settings: Auto or On?

It’s a frequent question among our customers: should I leave the fan inside my unit in the on position or in the auto position?

In our Floridian climate, we always recommend AUTO. In the auto setting, the fan only runs when the thermostat is calling for cooling (or heating). When the system is running in cool mode, the fan’s purpose is to circulate the air drawing warm air in from the returns and bringing it across the cold coil and out the supply air grilles as conditioned air. Many customers want to leave that air circulating. It might sound like a great idea, but it really isn’t. Why? It’s simple: when the system isn’t actively cooling, condensation begins to acculumate on the coil, and if you’re runnning the fan, that moisture attaches to the air molecules and actually increases the humidity level inside your home.

So, next time you want to increase airflow, try a ceiling fan but leave the thermostat on “auto”.

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