Batteries should be changed twice each year or near the start of summer and winter.
F.A.Q.
How often should I change my filter?
Filters should be changed every 1-3 months depending on the level of dust that accumulates in your home or business.
How often should I get my furnace or central air-conditioning system cleaned and checked?
Having a professional clean your system on a yearly basis can really add a lot of life to your furnace!