4. Replace furnace filters.
Why: The business of air filters is to collect debris and allergens, so be sure to replace them every three months to keep your furnace running effectively (and your home toasty!).
How: If in doubt, consult your manual, and be sure to note whether you’re working with a disposable or non-disposable filter (the latter can be washed with non-toxic soap and tap water).
Time: Five minutes.
Professional Help: N/A.