If you are installing new equipment, here are some of the most common add-ons worth considering:

Variable-speed blowers: Indoor fans (blowers) and/or outdoor fans of central air conditioners, heat pumps, and furnaces can be equipped to run from slow to fast as needed. The units are programmed to keep conditioned air continually moving at the lowest flow possible. These setups minimize cycling on and off (which contributes to wear and tear), dramatically help systems maintain consistent temperatures throughout different areas of homes, reduce energy usage, and decrease noise.

Variable output: Furnaces with this feature automatically select how much heat to generate, usually from between two levels; air conditioners and heat pumps with variable output automatically select how hard their compressors need to work to deliver conditioned air. Like variable-speed blowers, this feature lets equipment deliver warm or cool air continuously for longer periods of time, meaning equipment doesn’t have to cycle on and off frequently.

Programmable thermostats: These devices easily save you energy. If your home is unoccupied during the day, you can save five to 15 percent per year on energy bills by turning down the heat by 10F° to 15F° while you are away. A misconception associated with programmable thermostats is that when it is time to return the temperature to normal, the furnace must work so hard, and use so much energy, that little energy is saved. Much research has disproved this. Unfortunately, many homeowners who have programmable thermostats don’t use them, but new models make programming a snap; popular ones made by Nest and others even attempt to program themselves.

Electronic air filters: These gadgets, which use electrical charges to attract and trap particulates, can also reduce the amount of dust blown through systems. But there’s little evidence that they actually improve indoor air quality more than high-quality conventional filters do.

Desuperheaters: Some high-efficiency heat pumps can be equipped with these devices that capture waste heat generated from heat pumps during cooling mode and use it to heat water. Desuperheaters heat water two to three times more efficiently than conventional electric water heaters.

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