Winter is well underway, and when the temperatures dip, what could be more important than a reliable, efficient furnace?

But often homeowners neglect one simple action that keeps things running smoothly: regularly replacing the filter.

When it comes to furnace filters, Watkins Heating & Cooling, an Ohio company, offers the following advice:

Replace your filters routinely:

The amount of time between replacements will vary according to the home. If you have a large home or one with pets, the furnace works harder and the filter clogs faster. In these residences, Watkins recommends using a pleated 1” filter and changing it every month. If your home is smaller and pet-free, every two months should do the trick.

Buy your filters by the case:

The more filters you have on hand, the more likely you are to stick to your replacement schedule — not to mention the savings you’ll recoup by buying in volume. Cases usually hold 6-12 filters. Watkins suggests storing these spare filters near the furnace for easy access when replacing the old one.

Mark your calendar:

If you get into a routine – for example, changing the filter the 1st of every month – your furnace will thank you. A calendar reminder or monthly activity (bill paying, for example) may help you remember.

Use the correct filter:

Filters that don’t fit tightly allow dust and other particles to seep into your furnace and home. Be sure you know the size your furnace requires.

Turn off the power:

Before replacing the filter, turn off your furnace at the breaker panel or disconnect the power source. “Some furnaces have electrical wiring close to the filter location which could shock you if the power is not disconnected,” warns Watkins.

Realize that you get what you pay for:

Filters vary widely in price. More expensive filters generally require less frequent changes and collect more and smaller particles. The best value is a pleated filter for around $4-8 (no need to buy the Cadillac-priced options).