Should a thermostat be set to "auto" or "on"?
When the thermostat is set to "auto", the fan operates only when the temperature requires it (whenever the cooling unit or heating unit is running). When set to "on", the fan operates all the time. You may want the fan to run all the time to do its best possible job of filtering the air. If clean air is important or if you are an allergy sufferer, then you should investigate a furnace/heat pump that includes a "variable speed" fan. The variable speed fan will automatically switch to a lower speed when possible and can lower the cost of the fan as much as 85%. This can be a large savings on the power bill for customers who want to run the fan continuously.
